.. Copyright 2013-2022 Lawrence Livermore National Security, LLC and other Spack Project Developers. See the top-level COPYRIGHT file for details. SPDX-License-Identifier: (Apache-2.0 OR MIT) .. _packaging-guide: =============== Packaging Guide =============== This guide is intended for developers or administrators who want to package software so that Spack can install it. It assumes that you have at least some familiarity with Python, and that you've read the :ref:`basic usage guide `, especially the part about :ref:`specs `. There are two key parts of Spack: #. **Specs**: expressions for describing builds of software, and #. **Packages**: Python modules that describe how to build software according to a spec. Specs allow a user to describe a *particular* build in a way that a package author can understand. Packages allow the packager to encapsulate the build logic for different versions, compilers, options, platforms, and dependency combinations in one place. Essentially, a package translates a spec into build logic. Packages in Spack are written in pure Python, so you can do anything in Spack that you can do in Python. Python was chosen as the implementation language for two reasons. First, Python is becoming ubiquitous in the scientific software community. Second, it's a modern language and has many powerful features to help make package writing easy. .. _installation_procedure: -------------------------------------- Overview of the installation procedure -------------------------------------- Whenever Spack installs software, it goes through a series of predefined steps: .. image:: images/installation_pipeline.png :scale: 60 % :align: center All these steps are influenced by the metadata in each ``package.py`` and by the current Spack configuration. Since build systems are different from one another, the execution of the last block in the figure is further expanded in a build system specific way. An example for ``CMake`` is, for instance: .. image:: images/builder_phases.png :align: center :scale: 60 % The predefined steps for each build system are called "phases". In general, the name and order in which the phases will be executed can be obtained by either reading the API docs at :py:mod:`~.spack.build_systems`, or using the ``spack info`` command: .. code-block:: console :emphasize-lines: 13,14 $ spack info --phases m4 AutotoolsPackage: m4 Homepage: https://www.gnu.org/software/m4/m4.html Safe versions: 1.4.17 ftp://ftp.gnu.org/gnu/m4/m4-1.4.17.tar.gz Variants: Name Default Description sigsegv on Build the libsigsegv dependency Installation Phases: autoreconf configure build install Build Dependencies: libsigsegv ... An extensive list of available build systems and phases is provided in :ref:`installation_process`. ------------------------ Writing a package recipe ------------------------ Since v0.19, Spack supports two ways of writing a package recipe. The most commonly used is to encode both the metadata (directives, etc.) and the build behavior in a single class, like shown in the following example: .. code-block:: python class Openjpeg(CMakePackage): """OpenJPEG is an open-source JPEG 2000 codec written in C language""" homepage = "https://github.com/uclouvain/openjpeg" url = "https://github.com/uclouvain/openjpeg/archive/v2.3.1.tar.gz" version("2.4.0", sha256="8702ba68b442657f11aaeb2b338443ca8d5fb95b0d845757968a7be31ef7f16d") variant("codec", default=False, description="Build the CODEC executables") depends_on("libpng", when="+codec") def url_for_version(self, version): if version >= Version("2.1.1"): return super(Openjpeg, self).url_for_version(version) url_fmt = "https://github.com/uclouvain/openjpeg/archive/version.{0}.tar.gz" return url_fmt.format(version) def cmake_args(self): args = [ self.define_from_variant("BUILD_CODEC", "codec"), self.define("BUILD_MJ2", False), self.define("BUILD_THIRDPARTY", False), ] return args A package encoded with a single class is backward compatible with versions of Spack lower than v0.19, and so are custom repositories containing only recipes of this kind. The downside is that *this format doesn't allow packagers to use more than one build system in a single recipe*. To do that, we have to resort to the second way Spack has of writing packages, which involves writing a builder class explicitly. Using the same example as above, this reads: .. code-block:: python class Openjpeg(CMakePackage): """OpenJPEG is an open-source JPEG 2000 codec written in C language""" homepage = "https://github.com/uclouvain/openjpeg" url = "https://github.com/uclouvain/openjpeg/archive/v2.3.1.tar.gz" version("2.4.0", sha256="8702ba68b442657f11aaeb2b338443ca8d5fb95b0d845757968a7be31ef7f16d") variant("codec", default=False, description="Build the CODEC executables") depends_on("libpng", when="+codec") def url_for_version(self, version): if version >= Version("2.1.1"): return super(Openjpeg, self).url_for_version(version) url_fmt = "https://github.com/uclouvain/openjpeg/archive/version.{0}.tar.gz" return url_fmt.format(version) class CMakeBuilder(spack.build_systems.cmake.CMakeBuilder): def cmake_args(self): args = [ self.define_from_variant("BUILD_CODEC", "codec"), self.define("BUILD_MJ2", False), self.define("BUILD_THIRDPARTY", False), ] return args This way of writing packages allows extending the recipe to support multiple build systems, see :ref:`multiple_build_systems` for more details. The downside is that recipes of this kind are only understood by Spack since v0.19+. More information on the internal architecture of Spack can be found at :ref:`package_class_structure`. .. note:: If a builder is implemented in ``package.py``, all build-specific methods must be moved to the builder. This means that if you have a package like .. code-block:: python class Foo(CmakePackage): def cmake_args(self): ... and you add a builder to the ``package.py``, you must move ``cmake_args`` to the builder. .. _cmd-spack-create: --------------------- Creating new packages --------------------- To help creating a new package Spack provides a command that generates a ``package.py`` file in an existing repository, with a boilerplate package template. Here's an example: .. code-block:: console $ spack create https://gmplib.org/download/gmp/gmp-6.1.2.tar.bz2 Spack examines the tarball URL and tries to figure out the name of the package to be created. If the name contains uppercase letters, these are automatically converted to lowercase. If the name contains underscores or periods, these are automatically converted to dashes. Spack also searches for *additional* versions located in the same directory of the website. Spack prompts you to tell you how many versions it found and asks you how many you would like to download and checksum: .. code-block:: console $ spack create https://gmplib.org/download/gmp/gmp-6.1.2.tar.bz2 ==> This looks like a URL for gmp ==> Found 16 versions of gmp: 6.1.2 https://gmplib.org/download/gmp/gmp-6.1.2.tar.bz2 6.1.1 https://gmplib.org/download/gmp/gmp-6.1.1.tar.bz2 6.1.0 https://gmplib.org/download/gmp/gmp-6.1.0.tar.bz2 ... 5.0.0 https://gmplib.org/download/gmp/gmp-5.0.0.tar.bz2 How many would you like to checksum? (default is 1, q to abort) Spack will automatically download the number of tarballs you specify (starting with the most recent) and checksum each of them. You do not *have* to download all of the versions up front. You can always choose to download just one tarball initially, and run :ref:`cmd-spack-checksum` later if you need more versions. Spack automatically creates a directory in the appropriate repository, generates a boilerplate template for your package, and opens up the new ``package.py`` in your favorite ``$EDITOR``: .. code-block:: python :linenos: # Copyright 2013-2022 Lawrence Livermore National Security, LLC and other # Spack Project Developers. See the top-level COPYRIGHT file for details. # # SPDX-License-Identifier: (Apache-2.0 OR MIT) # ---------------------------------------------------------------------------- # If you submit this package back to Spack as a pull request, # please first remove this boilerplate and all FIXME comments. # # This is a template package file for Spack. We've put "FIXME" # next to all the things you'll want to change. Once you've handled # them, you can save this file and test your package like this: # # spack install gmp # # You can edit this file again by typing: # # spack edit gmp # # See the Spack documentation for more information on packaging. # ---------------------------------------------------------------------------- import spack.build_systems.autotools from spack.package import * class Gmp(AutotoolsPackage): """FIXME: Put a proper description of your package here.""" # FIXME: Add a proper url for your package's homepage here. homepage = "https://www.example.com" url = "https://gmplib.org/download/gmp/gmp-6.1.2.tar.bz2" # FIXME: Add a list of GitHub accounts to # notify when the package is updated. # maintainers = ["github_user1", "github_user2"] version("6.2.1", sha256="eae9326beb4158c386e39a356818031bd28f3124cf915f8c5b1dc4c7a36b4d7c") # FIXME: Add dependencies if required. # depends_on("foo") def configure_args(self): # FIXME: Add arguments other than --prefix # FIXME: If not needed delete the function args = [] return args The tedious stuff (creating the class, checksumming archives) has been done for you. Spack correctly detected that ``gmp`` uses the ``autotools`` build system, so it created a new ``Gmp`` package that subclasses the ``AutotoolsPackage`` base class. The default installation procedure for a package subclassing the ``AutotoolsPackage`` is to go through the typical process of: .. code-block:: bash ./configure --prefix=/path/to/installation/directory make make check make install For most Autotools packages, this is sufficient. If you need to add additional arguments to the ``./configure`` call, add them via the ``configure_args`` function. In the generated package, the download ``url`` attribute is already set. All the things you still need to change are marked with ``FIXME`` labels. You can delete the commented instructions between the license and the first import statement after reading them. The rest of the tasks you need to do are as follows: #. Add a description. Immediately inside the package class is a *docstring* in triple-quotes (``"""``). It is used to generate the description shown when users run ``spack info``. #. Change the ``homepage`` to a useful URL. The ``homepage`` is displayed when users run ``spack info`` so that they can learn more about your package. #. Add a comma-separated list of maintainers. The ``maintainers`` field is a list of GitHub accounts of people who want to be notified any time the package is modified. When a pull request is submitted that updates the package, these people will be requested to review the PR. This is useful for developers who maintain a Spack package for their own software, as well as users who rely on a piece of software and want to ensure that the package doesn't break. It also gives users a list of people to contact for help when someone reports a build error with the package. #. Add ``depends_on()`` calls for the package's dependencies. ``depends_on`` tells Spack that other packages need to be built and installed before this one. See :ref:`dependencies`. #. Get the installation working. Your new package may require specific flags during ``configure``. These can be added via ``configure_args``. Specifics will differ depending on the package and its build system. :ref:`installation_process` is covered in detail later. ^^^^^^^^^^^^^^^^^^^^^^^^^ Non-downloadable software ^^^^^^^^^^^^^^^^^^^^^^^^^ If your software cannot be downloaded from a URL you can still create a boilerplate ``package.py`` by telling ``spack create`` what name you want to use: .. code-block:: console $ spack create --name intel This will create a simple ``intel`` package with an ``install()`` method that you can craft to install your package. Likewise, you can force the build system to be used with ``--template`` and, in case it's needed, you can overwrite a package already in the repository with ``--force``: .. code-block:: console $ spack create --name gmp https://gmplib.org/download/gmp/gmp-6.1.2.tar.bz2 $ spack create --force --template autotools https://gmplib.org/download/gmp/gmp-6.1.2.tar.bz2 A complete list of available build system templates can be found by running ``spack create --help``. .. _cmd-spack-edit: ------------------------- Editing existing packages ------------------------- One of the easiest ways to learn how to write packages is to look at existing ones. You can edit a package file by name with the ``spack edit`` command: .. code-block:: console $ spack edit gmp If you used ``spack create`` to create a package, you can get back to it later with ``spack edit``. For instance, the ``gmp`` package actually lives in: .. code-block:: console $ spack location -p gmp ${SPACK_ROOT}/var/spack/repos/builtin/packages/gmp/package.py but ``spack edit`` provides a much simpler shortcut and saves you the trouble of typing the full path. ---------------------------- Naming & directory structure ---------------------------- This section describes how packages need to be named, and where they live in Spack's directory structure. In general, :ref:`cmd-spack-create` handles creating package files for you, so you can skip most of the details here. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ``var/spack/repos/builtin/packages`` ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ A Spack installation directory is structured like a standard UNIX install prefix (``bin``, ``lib``, ``include``, ``var``, ``opt``, etc.). Most of the code for Spack lives in ``$SPACK_ROOT/lib/spack``. Packages themselves live in ``$SPACK_ROOT/var/spack/repos/builtin/packages``. If you ``cd`` to that directory, you will see directories for each package: .. command-output:: cd $SPACK_ROOT/var/spack/repos/builtin/packages && ls :shell: :ellipsis: 10 Each directory contains a file called ``package.py``, which is where all the python code for the package goes. For example, the ``libelf`` package lives in: .. code-block:: none $SPACK_ROOT/var/spack/repos/builtin/packages/libelf/package.py Alongside the ``package.py`` file, a package may contain extra directories or files (like patches) that it needs to build. ^^^^^^^^^^^^^ Package Names ^^^^^^^^^^^^^ Packages are named after the directory containing ``package.py``. So, ``libelf``'s ``package.py`` lives in a directory called ``libelf``. The ``package.py`` file defines a class called ``Libelf``, which extends Spack's ``Package`` class. For example, here is ``$SPACK_ROOT/var/spack/repos/builtin/packages/libelf/package.py``: .. code-block:: python :linenos: from spack import * class Libelf(Package): """ ... description ... """ homepage = ... url = ... version(...) depends_on(...) def install(): ... The **directory name** (``libelf``) determines the package name that users should provide on the command line. e.g., if you type any of these: .. code-block:: console $ spack info libelf $ spack versions libelf $ spack install libelf@0.8.13 Spack sees the package name in the spec and looks for ``libelf/package.py`` in ``var/spack/repos/builtin/packages``. Likewise, if you run ``spack install py-numpy``, Spack looks for ``py-numpy/package.py``. Spack uses the directory name as the package name in order to give packagers more freedom in naming their packages. Package names can contain letters, numbers, and dashes. Using a Python identifier (e.g., a class name or a module name) would make it difficult to support these options. So, you can name a package ``3proxy`` or ``foo-bar`` and Spack won't care. It just needs to see that name in the packages directory. ^^^^^^^^^^^^^^^^^^^ Package class names ^^^^^^^^^^^^^^^^^^^ Spack loads ``package.py`` files dynamically, and it needs to find a special class name in the file for the load to succeed. The **class name** (``Libelf`` in our example) is formed by converting words separated by ``-`` in the file name to CamelCase. If the name starts with a number, we prefix the class name with ``_``. Here are some examples: ================= ================= Module Name Class Name ================= ================= ``foo-bar`` ``FooBar`` ``3proxy`` ``_3proxy`` ================= ================= In general, you won't have to remember this naming convention because :ref:`cmd-spack-create` and :ref:`cmd-spack-edit` handle the details for you. ----------------- Trusted Downloads ----------------- Spack verifies that the source code it downloads is not corrupted or compromised; or at least, that it is the same version the author of the Spack package saw when the package was created. If Spack uses a download method it can verify, we say the download method is *trusted*. Trust is important for *all downloads*: Spack has no control over the security of the various sites from which it downloads source code, and can never assume that any particular site hasn't been compromised. Trust is established in different ways for different download methods. For the most common download method --- a single-file tarball --- the tarball is checksummed. Git downloads using ``commit=`` are trusted implicitly, as long as a hash is specified. Spack also provides untrusted download methods: tarball URLs may be supplied without a checksum, or Git downloads may specify a branch or tag instead of a hash. If the user does not control or trust the source of an untrusted download, it is a security risk. Unless otherwise specified by the user for special cases, Spack should by default use *only* trusted download methods. Unfortunately, Spack does not currently provide that guarantee. It does provide the following mechanisms for safety: #. By default, Spack will only install a tarball package if it has a checksum and that checksum matches. You can override this with ``spack install --no-checksum``. #. Numeric versions are almost always tarball downloads, whereas non-numeric versions not named ``develop`` frequently download untrusted branches or tags from a version control system. As long as a package has at least one numeric version, and no non-numeric version named ``develop``, Spack will prefer it over any non-numeric versions. ^^^^^^^^^ Checksums ^^^^^^^^^ For tarball downloads, Spack can currently support checksums using the MD5, SHA-1, SHA-224, SHA-256, SHA-384, and SHA-512 algorithms. It determines the algorithm to use based on the hash length. .. _versions-and-fetching: --------------------- Versions and fetching --------------------- The most straightforward way to add new versions to your package is to add a line like this in the package class: .. code-block:: python class Foo(Package): url = "http://example.com/foo-1.0.tar.gz" version('8.2.1', '4136d7b4c04df68b686570afa26988ac') version('8.2.0', '1c9f62f0778697a09d36121ead88e08e') version('8.1.2', 'd47dd09ed7ae6e7fd6f9a816d7f5fdf6') Versions should be listed in descending order, from newest to oldest. ^^^^^^^^^^^^^ Date Versions ^^^^^^^^^^^^^ If you wish to use dates as versions, it is best to use the format ``@yyyy-mm-dd``. This will ensure they sort in the correct order. Alternately, you might use a hybrid release-version / date scheme. For example, ``@1.3_2016-08-31`` would mean the version from the ``1.3`` branch, as of August 31, 2016. ^^^^^^^^^^^^ Version URLs ^^^^^^^^^^^^ By default, each version's URL is extrapolated from the ``url`` field in the package. For example, Spack is smart enough to download version ``8.2.1`` of the ``Foo`` package above from http://example.com/foo-8.2.1.tar.gz. If the URL is particularly complicated or changes based on the release, you can override the default URL generation algorithm by defining your own ``url_for_version()`` function. For example, the download URL for OpenMPI contains the major.minor version in one spot and the major.minor.patch version in another: https://www.open-mpi.org/software/ompi/v2.1/downloads/openmpi-2.1.1.tar.bz2 In order to handle this, you can define a ``url_for_version()`` function like so: .. literalinclude:: _spack_root/var/spack/repos/builtin/packages/openmpi/package.py :pyobject: Openmpi.url_for_version With the use of this ``url_for_version()``, Spack knows to download OpenMPI ``2.1.1`` from http://www.open-mpi.org/software/ompi/v2.1/downloads/openmpi-2.1.1.tar.bz2 but download OpenMPI ``1.10.7`` from http://www.open-mpi.org/software/ompi/v1.10/downloads/openmpi-1.10.7.tar.bz2. You'll notice that OpenMPI's ``url_for_version()`` function makes use of a special ``Version`` function called ``up_to()``. When you call ``version.up_to(2)`` on a version like ``1.10.0``, it returns ``1.10``. ``version.up_to(1)`` would return ``1``. This can be very useful for packages that place all ``X.Y.*`` versions in a single directory and then places all ``X.Y.Z`` versions in a sub-directory. There are a few ``Version`` properties you should be aware of. We generally prefer numeric versions to be separated by dots for uniformity, but not all tarballs are named that way. For example, ``icu4c`` separates its major and minor versions with underscores, like ``icu4c-57_1-src.tgz``. The value ``57_1`` can be obtained with the use of the ``version.underscored`` property. Note that Python properties don't need parentheses. There are other separator properties as well: =================== ====== Property Result =================== ====== version.dotted 1.2.3 version.dashed 1-2-3 version.underscored 1_2_3 version.joined 123 =================== ====== .. note:: Python properties don't need parentheses. ``version.dashed`` is correct. ``version.dashed()`` is incorrect. In addition, these version properties can be combined with ``up_to()``. For example: .. code-block:: python >>> version = Version('1.2.3') >>> version.up_to(2).dashed Version('1-2') >>> version.underscored.up_to(2) Version('1_2') As you can see, order is not important. Just keep in mind that ``up_to()`` and the other version properties return ``Version`` objects, not strings. If a URL cannot be derived systematically, or there is a special URL for one of its versions, you can add an explicit URL for a particular version: .. code-block:: python version('8.2.1', '4136d7b4c04df68b686570afa26988ac', url='http://example.com/foo-8.2.1-special-version.tar.gz') When you supply a custom URL for a version, Spack uses that URL *verbatim* and does not perform extrapolation. The order of precedence of these methods is: #. package-level ``url`` #. ``url_for_version()`` #. version-specific ``url`` so if your package contains a ``url_for_version()``, it can be overridden by a version-specific ``url``. If your package does not contain a package-level ``url`` or ``url_for_version()``, Spack can determine which URL to download from even if only some of the versions specify their own ``url``. Spack will use the nearest URL *before* the requested version. This is useful for packages that have an easy to extrapolate URL, but keep changing their URL format every few releases. With this method, you only need to specify the ``url`` when the URL changes. """"""""""""""""""""""" Mirrors of the main URL """"""""""""""""""""""" Spack supports listing mirrors of the main URL in a package by defining the ``urls`` attribute: .. code-block:: python class Foo(Package): urls = [ 'http://example.com/foo-1.0.tar.gz', 'http://mirror.com/foo-1.0.tar.gz' ] instead of just a single ``url``. This attribute is a list of possible URLs that will be tried in order when fetching packages. Notice that either one of ``url`` or ``urls`` can be present in a package, but not both at the same time. A well-known case of packages that can be fetched from multiple mirrors is that of GNU. For that, Spack goes a step further and defines a mixin class that takes care of all of the plumbing and requires packagers to just define a proper ``gnu_mirror_path`` attribute: .. literalinclude:: _spack_root/var/spack/repos/builtin/packages/autoconf/package.py :lines: 9-18 ^^^^^^^^^^^^^^^^^^^^^^^^ Skipping the expand step ^^^^^^^^^^^^^^^^^^^^^^^^ Spack normally expands archives (e.g. ``*.tar.gz`` and ``*.zip``) automatically into a standard stage source directory (``self.stage.source_path``) after downloading them. If you want to skip this step (e.g., for self-extracting executables and other custom archive types), you can add ``expand=False`` to a ``version`` directive. .. code-block:: python version('8.2.1', '4136d7b4c04df68b686570afa26988ac', url='http://example.com/foo-8.2.1-special-version.sh', expand=False) When ``expand`` is set to ``False``, Spack sets the current working directory to the directory containing the downloaded archive before it calls your ``install`` method. Within ``install``, the path to the downloaded archive is available as ``self.stage.archive_file``. Here is an example snippet for packages distributed as self-extracting archives. The example sets permissions on the downloaded file to make it executable, then runs it with some arguments. .. code-block:: python def install(self, spec, prefix): set_executable(self.stage.archive_file) installer = Executable(self.stage.archive_file) installer('--prefix=%s' % prefix, 'arg1', 'arg2', 'etc.') .. _deprecate: ^^^^^^^^^^^^^^^^^^^^^^^^ Deprecating old versions ^^^^^^^^^^^^^^^^^^^^^^^^ There are many reasons to remove old versions of software: #. Security vulnerabilities (most serious reason) #. Changing build systems that increase package complexity #. Changing dependencies/patches/resources/flags that increase package complexity #. Maintainer/developer inability/unwillingness to support old versions #. No longer available for download (right to be forgotten) #. Package or version rename At the same time, there are many reasons to keep old versions of software: #. Reproducibility #. Requirements for older packages (e.g. some packages still rely on Qt 3) In general, you should not remove old versions from a ``package.py``. Instead, you should first deprecate them using the following syntax: .. code-block:: python version('1.2.3', sha256='...', deprecated=True) This has two effects. First, ``spack info`` will no longer advertise that version. Second, commands like ``spack install`` that fetch the package will require user approval: .. code-block:: console $ spack install openssl@1.0.1e ==> Warning: openssl@1.0.1e is deprecated and may be removed in a future Spack release. ==> Fetch anyway? [y/N] If you use ``spack install --deprecated``, this check can be skipped. This also applies to package recipes that are renamed or removed. You should first deprecate all versions before removing a package. If you need to rename it, you can deprecate the old package and create a new package at the same time. Version deprecations should always last at least one Spack minor release cycle before the version is completely removed. For example, if a version is deprecated in Spack 0.16.0, it should not be removed until Spack 0.17.0. No version should be removed without such a deprecation process. This gives users a chance to complain about the deprecation in case the old version is needed for some application. If you require a deprecated version of a package, simply submit a PR to remove ``deprecated=True`` from the package. However, you may be asked to help maintain this version of the package if the current maintainers are unwilling to support this older version. ^^^^^^^^^^^^^^^^ Download caching ^^^^^^^^^^^^^^^^ Spack maintains a cache (described :ref:`here `) which saves files retrieved during package installations to avoid re-downloading in the case that a package is installed with a different specification (but the same version) or reinstalled on account of a change in the hashing scheme. It may (rarely) be necessary to avoid caching for a particular version by adding ``no_cache=True`` as an option to the ``version()`` directive. Example situations would be a "snapshot"-like Version Control System (VCS) tag, a VCS branch such as ``v6-16-00-patches``, or a URL specifying a regularly updated snapshot tarball. ^^^^^^^^^^^^^^^^^^ Version comparison ^^^^^^^^^^^^^^^^^^ Most Spack versions are numeric, a tuple of integers; for example, ``apex@0.1``, ``ferret@6.96`` or ``py-netcdf@1.2.3.1``. Spack knows how to compare and sort numeric versions. Some Spack versions involve slight extensions of numeric syntax; for example, ``py-sphinx-rtd-theme@0.1.10a0``. In this case, numbers are always considered to be "newer" than letters. This is for consistency with `RPM `_. Spack versions may also be arbitrary non-numeric strings, for example ``@develop``, ``@master``, ``@local``. The order on versions is defined as follows. A version string is split into a list of components based on delimiters such as ``.``, ``-`` etc. Lists are then ordered lexicographically, where components are ordered as follows: #. The following special strings are considered larger than any other numeric or non-numeric version component, and satisfy the following order between themselves: ``develop > main > master > head > trunk > stable``. #. Numbers are ordered numerically, are less than special strings, and larger than other non-numeric components. #. All other non-numeric components are less than numeric components, and are ordered alphabetically. The logic behind this sort order is two-fold: #. Non-numeric versions are usually used for special cases while developing or debugging a piece of software. Keeping most of them less than numeric versions ensures that Spack chooses numeric versions by default whenever possible. #. The most-recent development version of a package will usually be newer than any released numeric versions. This allows the ``@develop`` version to satisfy dependencies like ``depends_on(abc, when="@x.y.z:")`` ^^^^^^^^^^^^^^^^^ Version selection ^^^^^^^^^^^^^^^^^ When concretizing, many versions might match a user-supplied spec. For example, the spec ``python`` matches all available versions of the package ``python``. Similarly, ``python@3:`` matches all versions of Python 3 and above. Given a set of versions that match a spec, Spack concretization uses the following priorities to decide which one to use: #. If the user provided a list of versions in ``packages.yaml``, the first matching version in that list will be used. #. If one or more versions is specified as ``preferred=True``, in either ``packages.yaml`` or ``package.py``, the largest matching version will be used. ("Latest" is defined by the sort order above). #. If no preferences in particular are specified in the package or in ``packages.yaml``, then the largest matching non-develop version will be used. By avoiding ``@develop``, this prevents users from accidentally installing a ``@develop`` version. #. If all else fails and ``@develop`` is the only matching version, it will be used. .. _cmd-spack-checksum: ^^^^^^^^^^^^^^^^^^ ``spack checksum`` ^^^^^^^^^^^^^^^^^^ If you want to add new versions to a package you've already created, this is automated with the ``spack checksum`` command. Here's an example for ``libelf``: .. code-block:: console $ spack checksum libelf ==> Found 16 versions of libelf. 0.8.13 http://www.mr511.de/software/libelf-0.8.13.tar.gz 0.8.12 http://www.mr511.de/software/libelf-0.8.12.tar.gz 0.8.11 http://www.mr511.de/software/libelf-0.8.11.tar.gz 0.8.10 http://www.mr511.de/software/libelf-0.8.10.tar.gz 0.8.9 http://www.mr511.de/software/libelf-0.8.9.tar.gz 0.8.8 http://www.mr511.de/software/libelf-0.8.8.tar.gz 0.8.7 http://www.mr511.de/software/libelf-0.8.7.tar.gz 0.8.6 http://www.mr511.de/software/libelf-0.8.6.tar.gz 0.8.5 http://www.mr511.de/software/libelf-0.8.5.tar.gz ... 0.5.2 http://www.mr511.de/software/libelf-0.5.2.tar.gz How many would you like to checksum? (default is 1, q to abort) This does the same thing that ``spack create`` does, but it allows you to go back and add new versions easily as you need them (e.g., as they're released). It fetches the tarballs you ask for and prints out a list of ``version`` commands ready to copy/paste into your package file: .. code-block:: console ==> Checksummed new versions of libelf: version('0.8.13', '4136d7b4c04df68b686570afa26988ac') version('0.8.12', 'e21f8273d9f5f6d43a59878dc274fec7') version('0.8.11', 'e931910b6d100f6caa32239849947fbf') version('0.8.10', '9db4d36c283d9790d8fa7df1f4d7b4d9') By default, Spack will search for new tarball downloads by scraping the parent directory of the tarball you gave it. So, if your tarball is at ``http://example.com/downloads/foo-1.0.tar.gz``, Spack will look in ``http://example.com/downloads/`` for links to additional versions. If you need to search another path for download links, you can supply some extra attributes that control how your package finds new versions. See the documentation on :ref:`attribute_list_url` and :ref:`attribute_list_depth`. .. note:: * This command assumes that Spack can extrapolate new URLs from an existing URL in the package, and that Spack can find similar URLs on a webpage. If that's not possible, e.g. if the package's developers don't name their tarballs consistently, you'll need to manually add ``version`` calls yourself. * For ``spack checksum`` to work, Spack needs to be able to ``import`` your package in Python. That means it can't have any syntax errors, or the ``import`` will fail. Use this once you've got your package in working order. -------------------- Finding new versions -------------------- You've already seen the ``homepage`` and ``url`` package attributes: .. code-block:: python :linenos: from spack import * class Mpich(Package): """MPICH is a high performance and widely portable implementation of the Message Passing Interface (MPI) standard.""" homepage = "http://www.mpich.org" url = "http://www.mpich.org/static/downloads/3.0.4/mpich-3.0.4.tar.gz" These are class-level attributes used by Spack to show users information about the package, and to determine where to download its source code. Spack uses the tarball URL to extrapolate where to find other tarballs of the same package (e.g. in :ref:`cmd-spack-checksum`, but this does not always work. This section covers ways you can tell Spack to find tarballs elsewhere. .. _attribute_list_url: ^^^^^^^^^^^^ ``list_url`` ^^^^^^^^^^^^ When spack tries to find available versions of packages (e.g. with :ref:`cmd-spack-checksum`), it spiders the parent directory of the tarball in the ``url`` attribute. For example, for libelf, the url is: .. code-block:: python url = "http://www.mr511.de/software/libelf-0.8.13.tar.gz" Here, Spack spiders ``http://www.mr511.de/software/`` to find similar tarball links and ultimately to make a list of available versions of ``libelf``. For many packages, the tarball's parent directory may be unlistable, or it may not contain any links to source code archives. In fact, many times additional package downloads aren't even available in the same directory as the download URL. For these, you can specify a separate ``list_url`` indicating the page to search for tarballs. For example, ``libdwarf`` has the homepage as the ``list_url``, because that is where links to old versions are: .. code-block:: python :linenos: class Libdwarf(Package): homepage = "http://www.prevanders.net/dwarf.html" url = "http://www.prevanders.net/libdwarf-20130729.tar.gz" list_url = homepage .. _attribute_list_depth: ^^^^^^^^^^^^^^ ``list_depth`` ^^^^^^^^^^^^^^ ``libdwarf`` and many other packages have a listing of available versions on a single webpage, but not all do. For example, ``mpich`` has a tarball URL that looks like this: .. code-block:: python url = "http://www.mpich.org/static/downloads/3.0.4/mpich-3.0.4.tar.gz" But its downloads are in many different subdirectories of ``http://www.mpich.org/static/downloads/``. So, we need to add a ``list_url`` *and* a ``list_depth`` attribute: .. code-block:: python :linenos: class Mpich(Package): homepage = "http://www.mpich.org" url = "http://www.mpich.org/static/downloads/3.0.4/mpich-3.0.4.tar.gz" list_url = "http://www.mpich.org/static/downloads/" list_depth = 1 By default, Spack only looks at the top-level page available at ``list_url``. ``list_depth = 1`` tells it to follow up to 1 level of links from the top-level page. Note that here, this implies 1 level of subdirectories, as the ``mpich`` website is structured much like a filesystem. But ``list_depth`` really refers to link depth when spidering the page. .. _vcs-fetch: ------------------------------- Fetching from code repositories ------------------------------- For some packages, source code is provided in a Version Control System (VCS) repository rather than in a tarball. Spack can fetch packages from VCS repositories. Currently, Spack supports fetching with `Git `_, `Mercurial (hg) `_, `Subversion (svn) `_, `CVS (cvs) `_, and `Go `_. In all cases, the destination is the standard stage source path. To fetch a package from a source repository, Spack needs to know which VCS to use and where to download from. Much like with ``url``, package authors can specify a class-level ``git``, ``hg``, ``svn``, ``cvs``, or ``go`` attribute containing the correct download location. Many packages developed with Git have both a Git repository as well as release tarballs available for download. Packages can define both a class-level tarball URL and VCS. For example: .. code-block:: python class Trilinos(CMakePackage): homepage = "https://trilinos.org/" url = "https://github.com/trilinos/Trilinos/archive/trilinos-release-12-12-1.tar.gz" git = "https://github.com/trilinos/Trilinos.git" version('develop', branch='develop') version('master', branch='master') version('12.12.1', 'ecd4606fa332212433c98bf950a69cc7') version('12.10.1', '667333dbd7c0f031d47d7c5511fd0810') version('12.8.1', '9f37f683ee2b427b5540db8a20ed6b15') If a package contains both a ``url`` and ``git`` class-level attribute, Spack decides which to use based on the arguments to the ``version()`` directive. Versions containing a specific branch, tag, or revision are assumed to be for VCS download methods, while versions containing a checksum are assumed to be for URL download methods. Like ``url``, if a specific version downloads from a different repository than the default repo, it can be overridden with a version-specific argument. .. note:: In order to reduce ambiguity, each package can only have a single VCS top-level attribute in addition to ``url``. In the rare case that a package uses multiple VCS, a fetch strategy can be specified for each version. For example, the ``rockstar`` package contains: .. code-block:: python class Rockstar(MakefilePackage): homepage = "https://bitbucket.org/gfcstanford/rockstar" version('develop', git='https://bitbucket.org/gfcstanford/rockstar.git') version('yt', hg='https://bitbucket.org/MatthewTurk/rockstar') .. _git-fetch: ^^^ Git ^^^ Git fetching supports the following parameters to ``version``: * ``git``: URL of the git repository, if different than the class-level ``git``. * ``branch``: Name of a branch to fetch. * ``tag``: Name of a tag to fetch. * ``commit``: SHA hash (or prefix) of a commit to fetch. * ``submodules``: Also fetch submodules recursively when checking out this repository. * ``submodules_delete``: A list of submodules to forcibly delete from the repository after fetching. Useful if a version in the repository has submodules that have disappeared/are no longer accessible. * ``get_full_repo``: Ensure the full git history is checked out with all remote branch information. Normally (``get_full_repo=False``, the default), the git option ``--depth 1`` will be used if the version of git and the specified transport protocol support it, and ``--single-branch`` will be used if the version of git supports it. Only one of ``tag``, ``branch``, or ``commit`` can be used at a time. The destination directory for the clone is the standard stage source path. Default branch To fetch a repository's default branch: .. code-block:: python class Example(Package): git = "https://github.com/example-project/example.git" version('develop') This download method is untrusted, and is not recommended. Aside from HTTPS, there is no way to verify that the repository has not been compromised, and the commit you get when you install the package likely won't be the same commit that was used when the package was first written. Additionally, the default branch may change. It is best to at least specify a branch name. Branches To fetch a particular branch, use the ``branch`` parameter: .. code-block:: python version('experimental', branch='experimental') This download method is untrusted, and is not recommended. Branches are moving targets, so the commit you get when you install the package likely won't be the same commit that was used when the package was first written. Tags To fetch from a particular tag, use ``tag`` instead: .. code-block:: python version('1.0.1', tag='v1.0.1') This download method is untrusted, and is not recommended. Although tags are generally more stable than branches, Git allows tags to be moved. Many developers use tags to denote rolling releases, and may move the tag when a bug is patched. Commits Finally, to fetch a particular commit, use ``commit``: .. code-block:: python version('2014-10-08', commit='9d38cd4e2c94c3cea97d0e2924814acc') This doesn't have to be a full hash; you can abbreviate it as you'd expect with git: .. code-block:: python version('2014-10-08', commit='9d38cd') This download method *is trusted*. It is the recommended way to securely download from a Git repository. It may be useful to provide a saner version for commits like this, e.g. you might use the date as the version, as done above. Or, if you know the commit at which a release was cut, you can use the release version. It's up to the package author to decide what makes the most sense. Although you can use the commit hash as the version number, this is not recommended, as it won't sort properly. Submodules You can supply ``submodules=True`` to cause Spack to fetch submodules recursively along with the repository at fetch time. .. code-block:: python version('1.0.1', tag='v1.0.1', submodules=True) If a package has needs more fine-grained control over submodules, define ``submodules`` to be a callable function that takes the package instance as its only argument. The function should return a list of submodules to be fetched. .. code-block:: python def submodules(package): submodules = [] if "+variant-1" in package.spec: submodules.append("submodule_for_variant_1") if "+variant-2" in package.spec: submodules.append("submodule_for_variant_2") return submodules class MyPackage(Package): version("0.1.0", submodules=submodules) For more information about git submodules see the manpage of git: ``man git-submodule``. .. _github-fetch: ^^^^^^ GitHub ^^^^^^ If a project is hosted on GitHub, *any* valid Git branch, tag, or hash may be downloaded as a tarball. This is accomplished simply by constructing an appropriate URL. Spack can checksum any package downloaded this way, thereby producing a trusted download. For example, the following downloads a particular hash, and then applies a checksum. .. code-block:: python version('1.9.5.1.1', 'd035e4bc704d136db79b43ab371b27d2', url='https://www.github.com/jswhit/pyproj/tarball/0be612cc9f972e38b50a90c946a9b353e2ab140f') .. _hg-fetch: ^^^^^^^^^ Mercurial ^^^^^^^^^ Fetching with Mercurial works much like `Git `_, but you use the ``hg`` parameter. The destination directory is still the standard stage source path. Default branch Add the ``hg`` attribute with no ``revision`` passed to ``version``: .. code-block:: python class Example(Package): hg = "https://bitbucket.org/example-project/example" version('develop') This download method is untrusted, and is not recommended. As with Git's default fetching strategy, there is no way to verify the integrity of the download. Revisions To fetch a particular revision, use the ``revision`` parameter: .. code-block:: python version('1.0', revision='v1.0') Unlike ``git``, which has special parameters for different types of revisions, you can use ``revision`` for branches, tags, and commits when you fetch with Mercurial. Like Git, fetching specific branches or tags is an untrusted download method, and is not recommended. The recommended fetch strategy is to specify a particular commit hash as the revision. .. _svn-fetch: ^^^^^^^^^^ Subversion ^^^^^^^^^^ To fetch with subversion, use the ``svn`` and ``revision`` parameters. The destination directory will be the standard stage source path. Fetching the head Simply add an ``svn`` parameter to the package: .. code-block:: python class Example(Package): svn = "https://outreach.scidac.gov/svn/example/trunk" version('develop') This download method is untrusted, and is not recommended for the same reasons as mentioned above. Fetching a revision To fetch a particular revision, add a ``revision`` argument to the version directive: .. code-block:: python version('develop', revision=128) This download method is untrusted, and is not recommended. Unfortunately, Subversion has no commit hashing scheme like Git and Mercurial do, so there is no way to guarantee that the download you get is the same as the download used when the package was created. Use at your own risk. Subversion branches are handled as part of the directory structure, so you can check out a branch or tag by changing the URL. If you want to package multiple branches, simply add a ``svn`` argument to each version directive. .. _cvs-fetch: ^^^ CVS ^^^ CVS (Concurrent Versions System) is an old centralized version control system. It is a predecessor of Subversion. To fetch with CVS, use the ``cvs``, branch, and ``date`` parameters. The destination directory will be the standard stage source path. Fetching the head Simply add a ``cvs`` parameter to the package: .. code-block:: python class Example(Package): cvs = ":pserver:outreach.scidac.gov/cvsroot%module=modulename" version('1.1.2.4') CVS repository locations are described using an older syntax that is different from today's ubiquitous URL syntax. ``:pserver:`` denotes the transport method. CVS servers can host multiple repositories (called "modules") at the same location, and one needs to specify both the server location and the module name to access. Spack combines both into one string using the ``%module=modulename`` suffix shown above. This download method is untrusted. Fetching a date Versions in CVS are commonly specified by date. To fetch a particular branch or date, add a ``branch`` and/or ``date`` argument to the version directive: .. code-block:: python version('2021.4.22', branch='branchname', date='2021-04-22') Unfortunately, CVS does not identify repository-wide commits via a revision or hash like Subversion, Git, or Mercurial do. This makes it impossible to specify an exact commit to check out. CVS has more features, but since CVS is rarely used these days, Spack does not support all of them. .. _go-fetch: ^^ Go ^^ Go isn't a VCS, it is a programming language with a builtin command, `go get `_, that fetches packages and their dependencies automatically. The destination directory will be the standard stage source path. This strategy can clone a Git repository, or download from another source location. For example: .. code-block:: python class ThePlatinumSearcher(Package): homepage = "https://github.com/monochromegane/the_platinum_searcher" go = "github.com/monochromegane/the_platinum_searcher/..." version('head') Go cannot be used to fetch a particular commit or branch, it always downloads the head of the repository. This download method is untrusted, and is not recommended. Use another fetch strategy whenever possible. -------- Variants -------- Many software packages can be configured to enable optional features, which often come at the expense of additional dependencies or longer build times. To be flexible enough and support a wide variety of use cases, Spack allows you to expose to the end-user the ability to choose which features should be activated in a package at the time it is installed. The mechanism to be employed is the :py:func:`spack.directives.variant` directive. ^^^^^^^^^^^^^^^^ Boolean variants ^^^^^^^^^^^^^^^^ In their simplest form variants are boolean options specified at the package level: .. code-block:: python class Hdf5(AutotoolsPackage): ... variant( 'shared', default=True, description='Builds a shared version of the library' ) with a default value and a description of their meaning / use in the package. *Variants can be tested in any context where a spec constraint is expected.* In the example above the ``shared`` variant is tied to the build of shared dynamic libraries. To pass the right option at configure time we can branch depending on its value: .. code-block:: python def configure_args(self): ... if '+shared' in self.spec: extra_args.append('--enable-shared') else: extra_args.append('--disable-shared') extra_args.append('--enable-static-exec') As explained in :ref:`basic-variants` the constraint ``+shared`` means that the boolean variant is set to ``True``, while ``~shared`` means it is set to ``False``. Another common example is the optional activation of an extra dependency which requires to use the variant in the ``when`` argument of :py:func:`spack.directives.depends_on`: .. code-block:: python class Hdf5(AutotoolsPackage): ... variant('szip', default=False, description='Enable szip support') depends_on('szip', when='+szip') as shown in the snippet above where ``szip`` is modeled to be an optional dependency of ``hdf5``. ^^^^^^^^^^^^^^^^^^^^^ Multi-valued variants ^^^^^^^^^^^^^^^^^^^^^ If need be, Spack can go beyond Boolean variants and permit an arbitrary number of allowed values. This might be useful when modeling options that are tightly related to each other. The values in this case are passed to the :py:func:`spack.directives.variant` directive as a tuple: .. code-block:: python class Blis(Package): ... variant( 'threads', default='none', description='Multithreading support', values=('pthreads', 'openmp', 'none'), multi=False ) In the example above the argument ``multi`` is set to ``False`` to indicate that only one among all the variant values can be active at any time. This constraint is enforced by the parser and an error is emitted if a user specifies two or more values at the same time: .. code-block:: console $ spack spec blis threads=openmp,pthreads Input spec -------------------------------- blis threads=openmp,pthreads Concretized -------------------------------- ==> Error: multiple values are not allowed for variant "threads" Another useful note is that *Python's* ``None`` *is not allowed as a default value* and therefore it should not be used to denote that no feature was selected. Users should instead select another value, like ``'none'``, and handle it explicitly within the package recipe if need be: .. code-block:: python if self.spec.variants['threads'].value == 'none': options.append('--no-threads') In cases where multiple values can be selected at the same time ``multi`` should be set to ``True``: .. code-block:: python class Gcc(AutotoolsPackage): ... variant( 'languages', default='c,c++,fortran', values=('ada', 'brig', 'c', 'c++', 'fortran', 'go', 'java', 'jit', 'lto', 'objc', 'obj-c++'), multi=True, description='Compilers and runtime libraries to build' ) Within a package recipe a multi-valued variant is tested using a ``key=value`` syntax: .. code-block:: python if 'languages=jit' in spec: options.append('--enable-host-shared') """"""""""""""""""""""""""""""""""""""""""" Complex validation logic for variant values """"""""""""""""""""""""""""""""""""""""""" To cover complex use cases, the :py:func:`spack.directives.variant` directive could accept as the ``values`` argument a full-fledged object which has ``default`` and other arguments of the directive embedded as attributes. An example, already implemented in Spack's core, is :py:class:`spack.variant.DisjointSetsOfValues`. This class is used to implement a few convenience functions, like :py:func:`spack.variant.any_combination_of`: .. code-block:: python class Adios(AutotoolsPackage): ... variant( 'staging', values=any_combination_of('flexpath', 'dataspaces'), description='Enable dataspaces and/or flexpath staging transports' ) that allows any combination of the specified values, and also allows the user to specify ``'none'`` (as a string) to choose none of them. The objects returned by these functions can be modified at will by chaining method calls to change the default value, customize the error message or other similar operations: .. code-block:: python class Mvapich2(AutotoolsPackage): ... variant( 'process_managers', description='List of the process managers to activate', values=disjoint_sets( ('auto',), ('slurm',), ('hydra', 'gforker', 'remshell') ).prohibit_empty_set().with_error( "'slurm' or 'auto' cannot be activated along with " "other process managers" ).with_default('auto').with_non_feature_values('auto'), ) """"""""""""""""""""""""""" Conditional Possible Values """"""""""""""""""""""""""" There are cases where a variant may take multiple values, and the list of allowed values expand over time. Think for instance at the C++ standard with which we might compile Boost, which can take one of multiple possible values with the latest standards only available from a certain version on. To model a similar situation we can use *conditional possible values* in the variant declaration: .. code-block:: python variant( 'cxxstd', default='98', values=( '98', '11', '14', # C++17 is not supported by Boost < 1.63.0. conditional('17', when='@1.63.0:'), # C++20/2a is not support by Boost < 1.73.0 conditional('2a', '2b', when='@1.73.0:') ), multi=False, description='Use the specified C++ standard when building.', ) The snippet above allows ``98``, ``11`` and ``14`` as unconditional possible values for the ``cxxstd`` variant, while ``17`` requires a version greater or equal to ``1.63.0`` and both ``2a`` and ``2b`` require a version greater or equal to ``1.73.0``. ^^^^^^^^^^^^^^^^^^^^ Conditional Variants ^^^^^^^^^^^^^^^^^^^^ The variant directive accepts a ``when`` clause. The variant will only be present on specs that otherwise satisfy the spec listed as the ``when`` clause. For example, the following class has a variant ``bar`` when it is at version 2.0 or higher. .. code-block:: python class Foo(Package): ... variant('bar', default=False, when='@2.0:', description='help message') The ``when`` clause follows the same syntax and accepts the same values as the ``when`` argument of :py:func:`spack.directives.depends_on` ^^^^^^^^^^^^^^^ Sticky Variants ^^^^^^^^^^^^^^^ The variant directive can be marked as ``sticky`` by setting to ``True`` the corresponding argument: .. code-block:: python variant('bar', default=False, sticky=True) A ``sticky`` variant differs from a regular one in that it is always set to either: #. An explicit value appearing in a spec literal or #. Its default value The concretizer thus is not free to pick an alternate value to work around conflicts, but will error out instead. Setting this property on a variant is useful in cases where the variant allows some dangerous or controversial options (e.g. using unsupported versions of a compiler for a library) and the packager wants to ensure that allowing these options is done on purpose by the user, rather than automatically by the solver. ^^^^^^^^^^^^^^^^^^^ Overriding Variants ^^^^^^^^^^^^^^^^^^^ Packages may override variants for several reasons, most often to change the default from a variant defined in a parent class or to change the conditions under which a variant is present on the spec. When a variant is defined multiple times, whether in the same package file or in a subclass and a superclass, the last definition is used for all attributes **except** for the ``when`` clauses. The ``when`` clauses are accumulated through all invocations, and the variant is present on the spec if any of the accumulated conditions are satisfied. For example, consider the following package: .. code-block:: python class Foo(Package): ... variant('bar', default=False, when='@1.0', description='help1') variant('bar', default=True, when='platform=darwin', description='help2') ... This package ``foo`` has a variant ``bar`` when the spec satisfies either ``@1.0`` or ``platform=darwin``, but not for other platforms at other versions. The default for this variant, when it is present, is always ``True``, regardless of which condition of the variant is satisfied. This allows packages to override variants in packages or build system classes from which they inherit, by modifying the variant values without modifying the ``when`` clause. It also allows a package to implement ``or`` semantics for a variant ``when`` clause by duplicating the variant definition. ------------------------------------ Resources (expanding extra tarballs) ------------------------------------ Some packages (most notably compilers) provide optional features if additional resources are expanded within their source tree before building. In Spack it is possible to describe such a need with the ``resource`` directive : .. code-block:: python resource( name='cargo', git='https://github.com/rust-lang/cargo.git', tag='0.10.0', destination='cargo' ) Based on the keywords present among the arguments the appropriate ``FetchStrategy`` will be used for the resource. The keyword ``destination`` is relative to the source root of the package and should point to where the resource is to be expanded. .. _license: ----------------- Licensed software ----------------- In order to install licensed software, Spack needs to know a few more details about a package. The following class attributes should be defined. ^^^^^^^^^^^^^^^^^^^^ ``license_required`` ^^^^^^^^^^^^^^^^^^^^ Boolean. If set to ``True``, this software requires a license. If set to ``False``, all of the following attributes will be ignored. Defaults to ``False``. ^^^^^^^^^^^^^^^^^^^ ``license_comment`` ^^^^^^^^^^^^^^^^^^^ String. Contains the symbol used by the license manager to denote a comment. Defaults to ``#``. ^^^^^^^^^^^^^^^^^ ``license_files`` ^^^^^^^^^^^^^^^^^ List of strings. These are files that the software searches for when looking for a license. All file paths must be relative to the installation directory. More complex packages like Intel may require multiple licenses for individual components. Defaults to the empty list. ^^^^^^^^^^^^^^^^ ``license_vars`` ^^^^^^^^^^^^^^^^ List of strings. Environment variables that can be set to tell the software where to look for a license if it is not in the usual location. Defaults to the empty list. ^^^^^^^^^^^^^^^ ``license_url`` ^^^^^^^^^^^^^^^ String. A URL pointing to license setup instructions for the software. Defaults to the empty string. For example, let's take a look at the package for the PGI compilers. .. code-block:: python # Licensing license_required = True license_comment = '#' license_files = ['license.dat'] license_vars = ['PGROUPD_LICENSE_FILE', 'LM_LICENSE_FILE'] license_url = 'http://www.pgroup.com/doc/pgiinstall.pdf' As you can see, PGI requires a license. Its license manager, FlexNet, uses the ``#`` symbol to denote a comment. It expects the license file to be named ``license.dat`` and to be located directly in the installation prefix. If you would like the installation file to be located elsewhere, simply set ``PGROUPD_LICENSE_FILE`` or ``LM_LICENSE_FILE`` after installation. For further instructions on installation and licensing, see the URL provided. Let's walk through a sample PGI installation to see exactly what Spack is and isn't capable of. Since PGI does not provide a download URL, it must be downloaded manually. It can either be added to a mirror or located in the current directory when ``spack install pgi`` is run. See :ref:`mirrors` for instructions on setting up a mirror. After running ``spack install pgi``, the first thing that will happen is Spack will create a global license file located at ``$SPACK_ROOT/etc/spack/licenses/pgi/license.dat``. It will then open up the file using the editor set in ``$EDITOR``, or vi if unset. It will look like this: .. code-block:: sh # A license is required to use pgi. # # The recommended solution is to store your license key in this global # license file. After installation, the following symlink(s) will be # added to point to this file (relative to the installation prefix): # # license.dat # # Alternatively, use one of the following environment variable(s): # # PGROUPD_LICENSE_FILE # LM_LICENSE_FILE # # If you choose to store your license in a non-standard location, you may # set one of these variable(s) to the full pathname to the license file, or # port@host if you store your license keys on a dedicated license server. # You will likely want to set this variable in a module file so that it # gets loaded every time someone tries to use pgi. # # For further information on how to acquire a license, please refer to: # # http://www.pgroup.com/doc/pgiinstall.pdf # # You may enter your license below. You can add your license directly to this file, or tell FlexNet to use a license stored on a separate license server. Here is an example that points to a license server called licman1: .. code-block:: none SERVER licman1.mcs.anl.gov 00163eb7fba5 27200 USE_SERVER If your package requires the license to install, you can reference the location of this global license using ``self.global_license_file``. After installation, symlinks for all of the files given in ``license_files`` will be created, pointing to this global license. If you install a different version or variant of the package, Spack will automatically detect and reuse the already existing global license. If the software you are trying to package doesn't rely on license files, Spack will print a warning message, letting the user know that they need to set an environment variable or pointing them to installation documentation. .. _patching: ------- Patches ------- Depending on the host architecture, package version, known bugs, or other issues, you may need to patch your software to get it to build correctly. Like many other package systems, spack allows you to store patches alongside your package files and apply them to source code after it's downloaded. ^^^^^^^^^ ``patch`` ^^^^^^^^^ You can specify patches in your package file with the ``patch()`` directive. ``patch`` looks like this: .. code-block:: python class Mvapich2(Package): ... patch('ad_lustre_rwcontig_open_source.patch', when='@1.9:') The first argument can be either a URL or a filename. It specifies a patch file that should be applied to your source. If the patch you supply is a filename, then the patch needs to live within the spack source tree. For example, the patch above lives in a directory structure like this: .. code-block:: none $SPACK_ROOT/var/spack/repos/builtin/packages/ mvapich2/ package.py ad_lustre_rwcontig_open_source.patch If you supply a URL instead of a filename, you need to supply a ``sha256`` checksum, like this: .. code-block:: python patch('http://www.nwchem-sw.org/images/Tddft_mxvec20.patch', sha256='252c0af58be3d90e5dc5e0d16658434c9efa5d20a5df6c10bf72c2d77f780866') Spack includes the hashes of patches in its versioning information, so that the same package with different patches applied will have different hash identifiers. To ensure that the hashing scheme is consistent, you must use a ``sha256`` checksum for the patch. Patches will be fetched from their URLs, checked, and applied to your source code. You can use the GNU utils ``sha256sum`` or the macOS ``shasum -a 256`` commands to generate a checksum for a patch file. Spack can also handle compressed patches. If you use these, Spack needs a little more help. Specifically, it needs *two* checksums: the ``sha256`` of the patch and ``archive_sha256`` for the compressed archive. ``archive_sha256`` helps Spack ensure that the downloaded file is not corrupted or malicious, before running it through a tool like ``tar`` or ``zip``. The ``sha256`` of the patch is still required so that it can be included in specs. Providing it in the package file ensures that Spack won't have to download and decompress patches it won't end up using at install time. Both the archive and patch checksum are checked when patch archives are downloaded. .. code-block:: python patch('http://www.nwchem-sw.org/images/Tddft_mxvec20.patch.gz', sha256='252c0af58be3d90e5dc5e0d16658434c9efa5d20a5df6c10bf72c2d77f780866', archive_sha256='4e8092a161ec6c3a1b5253176fcf33ce7ba23ee2ff27c75dbced589dabacd06e') ``patch`` keyword arguments are described below. """""""""""""""""""""""""""""" ``sha256``, ``archive_sha256`` """""""""""""""""""""""""""""" Hashes of downloaded patch and compressed archive, respectively. Only needed for patches fetched from URLs. """""""" ``when`` """""""" If supplied, this is a spec that tells spack when to apply the patch. If the installed package spec matches this spec, the patch will be applied. In our example above, the patch is applied when mvapich is at version ``1.9`` or higher. """"""""" ``level`` """"""""" This tells spack how to run the ``patch`` command. By default, the level is 1 and spack runs ``patch -p 1``. If level is 2, spack will run ``patch -p 2``, and so on. A lot of people are confused by level, so here's a primer. If you look in your patch file, you may see something like this: .. code-block:: diff :linenos: --- a/src/mpi/romio/adio/ad_lustre/ad_lustre_rwcontig.c 2013-12-10 12:05:44.806417000 -0800 +++ b/src/mpi/romio/adio/ad_lustre/ad_lustre_rwcontig.c 2013-12-10 11:53:03.295622000 -0800 @@ -8,7 +8,7 @@ * Copyright (C) 2008 Sun Microsystems, Lustre group \*/ -#define _XOPEN_SOURCE 600 +//#define _XOPEN_SOURCE 600 #include #include #include "ad_lustre.h" Lines 1-2 show paths with synthetic ``a/`` and ``b/`` prefixes. These are placeholders for the two ``mvapich2`` source directories that ``diff`` compared when it created the patch file. This is git's default behavior when creating patch files, but other programs may behave differently. ``-p1`` strips off the first level of the prefix in both paths, allowing the patch to be applied from the root of an expanded mvapich2 archive. If you set level to ``2``, it would strip off ``src``, and so on. It's generally easier to just structure your patch file so that it applies cleanly with ``-p1``, but if you're using a patch you didn't create yourself, ``level`` can be handy. """"""""""""""" ``working_dir`` """"""""""""""" This tells spack where to run the ``patch`` command. By default, the working directory is the source path of the stage (``.``). However, sometimes patches are made with respect to a subdirectory and this is where the working directory comes in handy. Internally, the working directory is given to ``patch`` via the ``-d`` option. Let's take the example patch from above and assume for some reason, it can only be downloaded in the following form: .. code-block:: diff :linenos: --- a/romio/adio/ad_lustre/ad_lustre_rwcontig.c 2013-12-10 12:05:44.806417000 -0800 +++ b/romio/adio/ad_lustre/ad_lustre_rwcontig.c 2013-12-10 11:53:03.295622000 -0800 @@ -8,7 +8,7 @@ * Copyright (C) 2008 Sun Microsystems, Lustre group \*/ -#define _XOPEN_SOURCE 600 +//#define _XOPEN_SOURCE 600 #include #include #include "ad_lustre.h" Hence, the patch needs to applied in the ``src/mpi`` subdirectory, and the ``working_dir='src/mpi'`` option would exactly do that. ^^^^^^^^^^^^^^^^^^^^^ Patch functions ^^^^^^^^^^^^^^^^^^^^^ In addition to supplying patch files, you can write a custom function to patch a package's source. For example, the ``py-pyside`` package contains some custom code for tweaking the way the PySide build handles ``RPATH``: .. _pyside-patch: .. literalinclude:: _spack_root/var/spack/repos/builtin/packages/py-pyside/package.py :pyobject: PyPyside.patch :linenos: A ``patch`` function, if present, will be run after patch files are applied and before ``install()`` is run. You could put this logic in ``install()``, but putting it in a patch function gives you some benefits. First, spack ensures that the ``patch()`` function is run once per code checkout. That means that if you run install, hit ctrl-C, and run install again, the code in the patch function is only run once. Also, you can tell Spack to run only the patching part of the build using the :ref:`cmd-spack-patch` command. .. _patch_dependency_patching: ^^^^^^^^^^^^^^^^^^^ Dependency patching ^^^^^^^^^^^^^^^^^^^ So far we've covered how the ``patch`` directive can be used by a package to patch *its own* source code. Packages can *also* specify patches to be applied to their dependencies, if they require special modifications. As with all packages in Spack, a patched dependency library can coexist with other versions of that library. See the `section on depends_on `_ for more details. .. _patch_inspecting_patches: ^^^^^^^^^^^^^^^^^^^ Inspecting patches ^^^^^^^^^^^^^^^^^^^ If you want to better understand the patches that Spack applies to your packages, you can do that using ``spack spec``, ``spack find``, and other query commands. Let's look at ``m4``. If you run ``spack spec m4``, you can see the patches that would be applied to ``m4``:: $ spack spec m4 Input spec -------------------------------- m4 Concretized -------------------------------- m4@1.4.18%apple-clang@9.0.0 patches=3877ab548f88597ab2327a2230ee048d2d07ace1062efe81fc92e91b7f39cd00,c0a408fbffb7255fcc75e26bd8edab116fc81d216bfd18b473668b7739a4158e,fc9b61654a3ba1a8d6cd78ce087e7c96366c290bc8d2c299f09828d793b853c8 +sigsegv arch=darwin-highsierra-x86_64 ^libsigsegv@2.11%apple-clang@9.0.0 arch=darwin-highsierra-x86_64 You can also see patches that have been applied to installed packages with ``spack find -v``:: $ spack find -v m4 ==> 1 installed package -- darwin-highsierra-x86_64 / apple-clang@9.0.0 ----------------- m4@1.4.18 patches=3877ab548f88597ab2327a2230ee048d2d07ace1062efe81fc92e91b7f39cd00,c0a408fbffb7255fcc75e26bd8edab116fc81d216bfd18b473668b7739a4158e,fc9b61654a3ba1a8d6cd78ce087e7c96366c290bc8d2c299f09828d793b853c8 +sigsegv .. _cmd-spack-resource: In both cases above, you can see that the patches' sha256 hashes are stored on the spec as a variant. As mentioned above, this means that you can have multiple, differently-patched versions of a package installed at once. You can look up a patch by its sha256 hash (or a short version of it) using the ``spack resource show`` command:: $ spack resource show 3877ab54 3877ab548f88597ab2327a2230ee048d2d07ace1062efe81fc92e91b7f39cd00 path: /home/spackuser/src/spack/var/spack/repos/builtin/packages/m4/gnulib-pgi.patch applies to: builtin.m4 ``spack resource show`` looks up downloadable resources from package files by hash and prints out information about them. Above, we see that the ``3877ab54`` patch applies to the ``m4`` package. The output also tells us where to find the patch. Things get more interesting if you want to know about dependency patches. For example, when ``dealii`` is built with ``boost@1.68.0``, it has to patch boost to work correctly. If you didn't know this, you might wonder where the extra boost patches are coming from:: $ spack spec dealii ^boost@1.68.0 ^hdf5+fortran | grep '\^boost' ^boost@1.68.0 ^boost@1.68.0%apple-clang@9.0.0+atomic+chrono~clanglibcpp cxxstd=default +date_time~debug+exception+filesystem+graph~icu+iostreams+locale+log+math~mpi+multithreaded~numpy patches=2ab6c72d03dec6a4ae20220a9dfd5c8c572c5294252155b85c6874d97c323199,b37164268f34f7133cbc9a4066ae98fda08adf51e1172223f6a969909216870f ~pic+program_options~python+random+regex+serialization+shared+signals~singlethreaded+system~taggedlayout+test+thread+timer~versionedlayout+wave arch=darwin-highsierra-x86_64 $ spack resource show b37164268 b37164268f34f7133cbc9a4066ae98fda08adf51e1172223f6a969909216870f path: /home/spackuser/src/spack/var/spack/repos/builtin/packages/dealii/boost_1.68.0.patch applies to: builtin.boost patched by: builtin.dealii Here you can see that the patch is applied to ``boost`` by ``dealii``, and that it lives in ``dealii``'s directory in Spack's ``builtin`` package repository. .. _handling_rpaths: --------------- Handling RPATHs --------------- Spack installs each package in a way that ensures that all of its dependencies are found when it runs. It does this using `RPATHs `_. An RPATH is a search path, stored in a binary (an executable or library), that tells the dynamic loader where to find its dependencies at runtime. You may be familiar with `LD_LIBRARY_PATH `_ on Linux or `DYLD_LIBRARY_PATH `_ on Mac OS X. RPATH is similar to these paths, in that it tells the loader where to find libraries. Unlike them, it is embedded in the binary and not set in each user's environment. RPATHs in Spack are handled in one of three ways: #. For most packages, RPATHs are handled automatically using Spack's :ref:`compiler wrappers `. These wrappers are set in standard variables like ``CC``, ``CXX``, ``F77``, and ``FC``, so most build systems (autotools and many gmake systems) pick them up and use them. #. CMake also respects Spack's compiler wrappers, but many CMake builds have logic to overwrite RPATHs when binaries are installed. Spack provides the ``std_cmake_args`` variable, which includes parameters necessary for CMake build use the right installation RPATH. It can be used like this when ``cmake`` is invoked: .. code-block:: python class MyPackage(Package): ... def install(self, spec, prefix): cmake('..', *std_cmake_args) make() make('install') #. If you need to modify the build to add your own RPATHs, you can use the ``self.rpath`` property of your package, which will return a list of all the RPATHs that Spack will use when it links. You can see this how this is used in the :ref:`PySide example ` above. .. _attribute_parallel: --------------- Parallel builds --------------- Spack supports parallel builds on an individual package and at the installation level. Package-level parallelism is established by the ``--jobs`` option and its configuration and package recipe equivalents. Installation-level parallelism is driven by the DAG(s) of the requested package or packages. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Package-level build parallelism ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ By default, Spack will invoke ``make()``, or any other similar tool, with a ``-j `` argument, so those builds run in parallel. The parallelism is determined by the value of the ``build_jobs`` entry in ``config.yaml`` (see :ref:`here ` for more details on how this value is computed). If a package does not build properly in parallel, you can override this setting by adding ``parallel = False`` to your package. For example, OpenSSL's build does not work in parallel, so its package looks like this: .. code-block:: python :emphasize-lines: 8 :linenos: class Openssl(Package): homepage = "http://www.openssl.org" url = "http://www.openssl.org/source/openssl-1.0.1h.tar.gz" version('1.0.1h', '8d6d684a9430d5cc98a62a5d8fbda8cf') depends_on("zlib") parallel = False Similarly, you can disable parallel builds only for specific make commands, as ``libdwarf`` does: .. code-block:: python :emphasize-lines: 9, 12 :linenos: class Libelf(Package): ... def install(self, spec, prefix): configure("--prefix=" + prefix, "--enable-shared", "--disable-dependency-tracking", "--disable-debug") make() # The mkdir commands in libelf's install can fail in parallel make("install", parallel=False) The first make will run in parallel here, but the second will not. If you set ``parallel`` to ``False`` at the package level, then each call to ``make()`` will be sequential by default, but packagers can call ``make(parallel=True)`` to override it. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Install-level build parallelism ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Spack supports the concurrent installation of packages within a Spack instance across multiple processes using file system locks. This parallelism is separate from the package-level achieved through build systems' use of the ``-j `` option. With install-level parallelism, processes coordinate the installation of the dependencies of specs provided on the command line and as part of an environment build with only **one process** being allowed to install a given package at a time. Refer to :ref:`Dependencies` for more information on dependencies and :ref:`installing-environment` for how to install an environment. Concurrent processes may be any combination of interactive sessions and batch jobs. Which means a ``spack install`` can be running in a terminal window while a batch job is running ``spack install`` on the same or overlapping dependencies without any process trying to re-do the work of another. For example, if you are using SLURM, you could launch an installation of ``mpich`` using the following command: .. code-block:: console $ srun -N 2 -n 8 spack install -j 4 mpich@3.3.2 This will create eight concurrent, four-job installs on two different nodes. Alternatively, you could run the same installs on one node by entering the following at the command line of a bash shell: .. code-block:: console $ for i in {1..12}; do nohup spack install -j 4 mpich@3.3.2 >> mpich_install.txt 2>&1 &; done .. note:: The effective parallelism is based on the maximum number of packages that can be installed at the same time, which is limited by the number of packages with no (remaining) uninstalled dependencies. .. _dependencies: ------------ Dependencies ------------ We've covered how to build a simple package, but what if one package relies on another package to build? How do you express that in a package file? And how do you refer to the other package in the build script for your own package? Spack makes this relatively easy. Let's take a look at the ``libdwarf`` package to see how it's done: .. code-block:: python :emphasize-lines: 9 :linenos: class Libdwarf(Package): homepage = "http://www.prevanders.net/dwarf.html" url = "http://www.prevanders.net/libdwarf-20130729.tar.gz" list_url = homepage version('20130729', '4cc5e48693f7b93b7aa0261e63c0e21d') ... depends_on("libelf") def install(self, spec, prefix): ... ^^^^^^^^^^^^^^^^ ``depends_on()`` ^^^^^^^^^^^^^^^^ The highlighted ``depends_on('libelf')`` call tells Spack that it needs to build and install the ``libelf`` package before it builds ``libdwarf``. This means that in your ``install()`` method, you are guaranteed that ``libelf`` has been built and installed successfully, so you can rely on it for your libdwarf build. ^^^^^^^^^^^^^^^^ Dependency specs ^^^^^^^^^^^^^^^^ ``depends_on`` doesn't just take the name of another package. It can take a full spec as well. This means that you can restrict the versions or other configuration options of ``libelf`` that ``libdwarf`` will build with. For example, suppose that in the ``libdwarf`` package you write: .. code-block:: python depends_on('libelf@0.8') Now ``libdwarf`` will require ``libelf`` at *exactly* version ``0.8``. You can also specify a requirement for a particular variant or for specific compiler flags: .. code-block:: python depends_on('libelf@0.8+debug') depends_on('libelf debug=True') depends_on('libelf cppflags="-fPIC"') Both users *and* package authors can use the same spec syntax to refer to different package configurations. Users use the spec syntax on the command line to find installed packages or to install packages with particular constraints, and package authors can use specs to describe relationships between packages. ^^^^^^^^^^^^^^ Version ranges ^^^^^^^^^^^^^^ Although some packages require a specific version for their dependencies, most can be built with a range of versions. For example, if you are writing a package for a legacy Python module that only works with Python 2.4 through 2.6, this would look like: .. code-block:: python depends_on('python@2.4:2.6') Version ranges in Spack are *inclusive*, so ``2.4:2.6`` means any version greater than or equal to ``2.4`` and up to and including any ``2.6.x``. If you want to specify that a package works with any version of Python 3 (or higher), this would look like: .. code-block:: python depends_on('python@3:') Here we leave out the upper bound. If you want to say that a package requires Python 2, you can similarly leave out the lower bound: .. code-block:: python depends_on('python@:2') Notice that we didn't use ``@:3``. Version ranges are *inclusive*, so ``@:3`` means "up to and including any 3.x version". What if a package can only be built with Python 2.7? You might be inclined to use: .. code-block:: python depends_on('python@2.7') However, this would be wrong. Spack assumes that all version constraints are exact, so it would try to install Python not at ``2.7.18``, but exactly at ``2.7``, which is a non-existent version. The correct way to specify this would be: .. code-block:: python depends_on('python@2.7.0:2.7') A spec can contain a version list of ranges and individual versions separated by commas. For example, if you need Boost 1.59.0 or newer, but there are known issues with 1.64.0, 1.65.0, and 1.66.0, you can say: .. code-block:: python depends_on('boost@1.59.0:1.63,1.65.1,1.67.0:') .. _dependency-types: ^^^^^^^^^^^^^^^^ Dependency types ^^^^^^^^^^^^^^^^ Not all dependencies are created equal, and Spack allows you to specify exactly what kind of a dependency you need. For example: .. code-block:: python depends_on('cmake', type='build') depends_on('py-numpy', type=('build', 'run')) depends_on('libelf', type=('build', 'link')) depends_on('py-pytest', type='test') The following dependency types are available: * **"build"**: the dependency will be added to the ``PATH`` and ``PYTHONPATH`` at build-time. * **"link"**: the dependency will be added to Spack's compiler wrappers, automatically injecting the appropriate linker flags, including ``-I``, ``-L``, and RPATH/RUNPATH handling. * **"run"**: the dependency will be added to the ``PATH`` and ``PYTHONPATH`` at run-time. This is true for both ``spack load`` and the module files Spack writes. * **"test"**: the dependency will be added to the ``PATH`` and ``PYTHONPATH`` at build-time. The only difference between "build" and "test" is that test dependencies are only built if the user requests unit tests with ``spack install --test``. One of the advantages of the ``build`` dependency type is that although the dependency needs to be installed in order for the package to be built, it can be uninstalled without concern afterwards. ``link`` and ``run`` disallow this because uninstalling the dependency would break the package. ``build``, ``link``, and ``run`` dependencies all affect the hash of Spack packages (along with ``sha256`` sums of patches and archives used to build the package, and a [canonical hash](https://github.com/spack/spack/pull/28156) of the ``package.py`` recipes). ``test`` dependencies do not affect the package hash, as they are only used to construct a test environment *after* building and installing a given package installation. Older versions of Spack did not include build dependencies in the hash, but this has been [fixed](https://github.com/spack/spack/pull/28504) as of [Spack ``v0.18``](https://github.com/spack/spack/releases/tag/v0.18.0) If the dependency type is not specified, Spack uses a default of ``('build', 'link')``. This is the common case for compiler languages. Non-compiled packages like Python modules commonly use ``('build', 'run')``. This means that the compiler wrappers don't need to inject the dependency's ``prefix/lib`` directory, but the package needs to be in ``PATH`` and ``PYTHONPATH`` during the build process and later when a user wants to run the package. ^^^^^^^^^^^^^^^^^^^^^^^^ Conditional dependencies ^^^^^^^^^^^^^^^^^^^^^^^^ You may have a package that only requires a dependency under certain conditions. For example, you may have a package that has optional MPI support, - MPI is only a dependency when you want to enable MPI support for the package. In that case, you could say something like: .. code-block:: python variant('mpi', default=False, description='Enable MPI support') depends_on('mpi', when='+mpi') ``when`` can include constraints on the variant, version, compiler, etc. and the :mod:`syntax` is the same as for Specs written on the command line. If a dependency/feature of a package isn't typically used, you can save time by making it conditional (since Spack will not build the dependency unless it is required for the Spec). .. _dependency_dependency_patching: ^^^^^^^^^^^^^^^^^^^ Dependency patching ^^^^^^^^^^^^^^^^^^^ Some packages maintain special patches on their dependencies, either to add new features or to fix bugs. This typically makes a package harder to maintain, and we encourage developers to upstream (contribute back) their changes rather than maintaining patches. However, in some cases it's not possible to upstream. Maybe the dependency's developers don't accept changes, or maybe they just haven't had time to integrate them. For times like these, Spack's ``depends_on`` directive can optionally take a patch or list of patches: .. code-block:: python class SpecialTool(Package): ... depends_on('binutils', patches='special-binutils-feature.patch') ... Here, the ``special-tool`` package requires a special feature in ``binutils``, so it provides an extra ``patches=`` keyword argument. This is similar to the `patch directive `_, with one small difference. Here, ``special-tool`` is responsible for the patch, so it should live in ``special-tool``'s directory in the package repository, not the ``binutils`` directory. If you need something more sophisticated than this, you can simply nest a ``patch()`` directive inside of ``depends_on``: .. code-block:: python class SpecialTool(Package): ... depends_on( 'binutils', patches=patch('special-binutils-feature.patch', level=3, when='@:1.3'), # condition on binutils when='@2.0:') # condition on special-tool ... Note that there are two optional ``when`` conditions here -- one on the ``patch`` directive and the other on ``depends_on``. The condition in the ``patch`` directive applies to ``binutils`` (the package being patched), while the condition in ``depends_on`` applies to ``special-tool``. See `patch directive `_ for details on all the arguments the ``patch`` directive can take. Finally, if you need *multiple* patches on a dependency, you can provide a list for ``patches``, e.g.: .. code-block:: python class SpecialTool(Package): ... depends_on( 'binutils', patches=[ 'binutils-bugfix1.patch', 'binutils-bugfix2.patch', patch('https://example.com/special-binutils-feature.patch', sha256='252c0af58be3d90e5dc5e0d16658434c9efa5d20a5df6c10bf72c2d77f780866', when='@:1.3')], when='@2.0:') ... As with ``patch`` directives, patches are applied in the order they appear in the package file (or in this case, in the list). .. note:: You may wonder whether dependency patching will interfere with other packages that depend on ``binutils``. It won't. As described in patching_, Patching a package adds the ``sha256`` of the patch to the package's spec, which means it will have a *different* unique hash than other versions without the patch. The patched version coexists with unpatched versions, and Spack's support for handling_rpaths_ guarantees that each installation finds the right version. If two packages depend on ``binutils`` patched *the same* way, they can both use a single installation of ``binutils``. .. _setup-dependent-environment: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Influence how dependents are built or run ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Spack provides a mechanism for dependencies to influence the environment of their dependents by overriding the :meth:`setup_dependent_run_environment ` or the :meth:`setup_dependent_build_environment ` methods. The Qt package, for instance, uses this call: .. literalinclude:: _spack_root/var/spack/repos/builtin/packages/qt/package.py :pyobject: Qt.setup_dependent_build_environment :linenos: to set the ``QTDIR`` environment variable so that packages that depend on a particular Qt installation will find it. Another good example of how a dependency can influence the build environment of dependents is the Python package: .. literalinclude:: _spack_root/var/spack/repos/builtin/packages/python/package.py :pyobject: Python.setup_dependent_build_environment :linenos: In the method above it is ensured that any package that depends on Python will have the ``PYTHONPATH``, ``PYTHONHOME`` and ``PATH`` environment variables set appropriately before starting the installation. To make things even simpler the ``python setup.py`` command is also inserted into the module scope of dependents by overriding a third method called :meth:`setup_dependent_package ` : .. literalinclude:: _spack_root/var/spack/repos/builtin/packages/python/package.py :pyobject: Python.setup_dependent_package :linenos: This allows most python packages to have a very simple install procedure, like the following: .. code-block:: python def install(self, spec, prefix): setup_py('install', '--prefix={0}'.format(prefix)) Finally the Python package takes also care of the modifications to ``PYTHONPATH`` to allow dependencies to run correctly: .. literalinclude:: _spack_root/var/spack/repos/builtin/packages/python/package.py :pyobject: Python.setup_dependent_run_environment :linenos: .. _packaging_conflicts: --------- Conflicts --------- Sometimes packages have known bugs, or limitations, that would prevent them to build e.g. against other dependencies or with certain compilers. Spack makes it possible to express such constraints with the ``conflicts`` directive. Adding the following to a package: .. code-block:: python conflicts('%intel', when='@:1.2', msg=' <= v1.2 cannot be built with Intel ICC, ' 'please use a newer release.') we express the fact that the current package *cannot be built* with the Intel compiler when we are trying to install a version "<=1.2". The ``when`` argument can be omitted, in which case the conflict will always be active. Conflicts are always evaluated after the concretization step has been performed, and if any match is found a detailed error message is shown to the user. You can add an additional message via the ``msg=`` parameter to a conflict that provideds more specific instructions for users. .. _packaging_extensions: ---------- Extensions ---------- Spack's support for package extensions is documented extensively in :ref:`extensions`. This section documents how to make your own extendable packages and extensions. To support extensions, a package needs to set its ``extendable`` property to ``True``, e.g.: .. code-block:: python class Python(Package): ... extendable = True ... To make a package into an extension, simply add an ``extends`` call in the package definition, and pass it the name of an extendable package: .. code-block:: python class PyNumpy(Package): ... extends('python') ... This accomplishes a few things. Firstly, the Python package can set special variables such as ``PYTHONPATH`` for all extensions when the run or build environment is set up. Secondly, filesystem views can ensure that extensions are put in the same prefix as their extendee. This ensures that Python in a view can always locate its Python packages, even without environment variables set. A package can only extend one other package at a time. To support packages that may extend one of a list of other packages, Spack supports multiple ``extends`` directives as long as at most one of them is selected as a dependency during concretization. For example, a lua package could extend either lua or luajit, but not both: .. code-block:: python class LuaLpeg(Package): ... variant('use_lua', default=True) extends('lua', when='+use_lua') extends('lua-luajit', when='~use_lua') ... Now, a user can install, and activate, the ``lua-lpeg`` package for either lua or luajit. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Adding additional constraints ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Some packages produce a Python extension, but are only compatible with Python 3, or with Python 2. In those cases, a ``depends_on()`` declaration should be made in addition to the ``extends()`` declaration: .. code-block:: python class Icebin(Package): extends('python', when='+python') depends_on('python@3:', when='+python') Many packages produce Python extensions for *some* variants, but not others: they should extend ``python`` only if the appropriate variant(s) are selected. This may be accomplished with conditional ``extends()`` declarations: .. code-block:: python class FooLib(Package): variant('python', default=True, description='Build the Python extension Module') extends('python', when='+python') ... Sometimes, certain files in one package will conflict with those in another, which means they cannot both be used in a view at the same time. In this case, you can tell Spack to ignore those files: .. code-block:: python class PySncosmo(Package): ... # py-sncosmo binaries are duplicates of those from py-astropy extends('python', ignore=r'bin/.*') depends_on('py-astropy') ... The code above will prevent everything in the ``$prefix/bin/`` directory from being linked in a view. .. note:: You can call *either* ``depends_on`` or ``extends`` on any one package, but not both. For example you cannot both ``depends_on('python')`` and ``extends(python)`` in the same package. ``extends`` implies ``depends_on``. ----- Views ----- The ``spack view`` command can be used to symlink a number of packages into a merged prefix. The methods of ``PackageViewMixin`` can be overridden to customize how packages are added to views. Generally this can be used to create copies of specific files rather than symlinking them when symlinking does not work. For example, ``Python`` overrides ``add_files_to_view`` in order to create a copy of the ``python`` binary since the real path of the Python executable is used to detect extensions; as a consequence python extension packages (those inheriting from ``PythonPackage``) likewise override ``add_files_to_view`` in order to rewrite shebang lines which point to the Python interpreter. .. _virtual-dependencies: -------------------- Virtual dependencies -------------------- In some cases, more than one package can satisfy another package's dependency. One way this can happen is if a package depends on a particular *interface*, but there are multiple *implementations* of the interface, and the package could be built with any of them. A *very* common interface in HPC is the `Message Passing Interface (MPI) `_, which is used in many large-scale parallel applications. MPI has several different implementations (e.g., `MPICH `_, `OpenMPI `_, and `MVAPICH `_) and scientific applications can be built with any one of them. Complicating matters, MPI does not have a standardized ABI, so a package built with one implementation cannot simply be relinked with another implementation. Many package managers handle interfaces like this by requiring many similar package files, e.g., ``foo``, ``foo-mvapich``, ``foo-mpich``, but Spack avoids this explosion of package files by providing support for *virtual dependencies*. ^^^^^^^^^^^^ ``provides`` ^^^^^^^^^^^^ In Spack, ``mpi`` is handled as a *virtual package*. A package like ``mpileaks`` can depend on it just like any other package, by supplying a ``depends_on`` call in the package definition. For example: .. code-block:: python :linenos: :emphasize-lines: 7 class Mpileaks(Package): homepage = "https://github.com/hpc/mpileaks" url = "https://github.com/hpc/mpileaks/releases/download/v1.0/mpileaks-1.0.tar.gz" version('1.0', '8838c574b39202a57d7c2d68692718aa') depends_on("mpi") depends_on("adept-utils") depends_on("callpath") Here, ``callpath`` and ``adept-utils`` are concrete packages, but there is no actual package file for ``mpi``, so we say it is a *virtual* package. The syntax of ``depends_on``, is the same for both. If we look inside the package file of an MPI implementation, say MPICH, we'll see something like this: .. code-block:: python class Mpich(Package): provides('mpi') ... The ``provides("mpi")`` call tells Spack that the ``mpich`` package can be used to satisfy the dependency of any package that ``depends_on('mpi')``. ^^^^^^^^^^^^^^^^^^^^ Versioned Interfaces ^^^^^^^^^^^^^^^^^^^^ Just as you can pass a spec to ``depends_on``, so can you pass a spec to ``provides`` to add constraints. This allows Spack to support the notion of *versioned interfaces*. The MPI standard has gone through many revisions, each with new functions added, and each revision of the standard has a version number. Some packages may require a recent implementation that supports MPI-3 functions, but some MPI versions may only provide up to MPI-2. Others may need MPI 2.1 or higher. You can indicate this by adding a version constraint to the spec passed to ``provides``: .. code-block:: python provides("mpi@:2") Suppose that the above ``provides`` call is in the ``mpich2`` package. This says that ``mpich2`` provides MPI support *up to* version 2, but if a package ``depends_on("mpi@3")``, then Spack will *not* build that package with ``mpich2``. ^^^^^^^^^^^^^^^^^ ``provides when`` ^^^^^^^^^^^^^^^^^ The same package may provide different versions of an interface depending on *its* version. Above, we simplified the ``provides`` call in ``mpich`` to make the explanation easier. In reality, this is how ``mpich`` calls ``provides``: .. code-block:: python provides('mpi@:3', when='@3:') provides('mpi@:1', when='@1:') The ``when`` argument to ``provides`` allows you to specify optional constraints on the *providing* package, or the *provider*. The provider only provides the declared virtual spec when *it* matches the constraints in the when clause. Here, when ``mpich`` is at version 3 or higher, it provides MPI up to version 3. When ``mpich`` is at version 1 or higher, it provides the MPI virtual package at version 1. The ``when`` qualifier ensures that Spack selects a suitably high version of ``mpich`` to satisfy some other package that ``depends_on`` a particular version of MPI. It will also prevent a user from building with too low a version of ``mpich``. For example, suppose the package ``foo`` declares this: .. code-block:: python class Foo(Package): ... depends_on('mpi@2') Suppose a user invokes ``spack install`` like this: .. code-block:: console $ spack install foo ^mpich@1.0 Spack will fail with a constraint violation, because the version of MPICH requested is too low for the ``mpi`` requirement in ``foo``. .. _custom-attributes: ------------------ Custom attributes ------------------ Often a package will need to provide attributes for dependents to query various details about what it provides. While any number of custom defined attributes can be implemented by a package, the four specific attributes described below are always available on every package with default implementations and the ability to customize with alternate implementations in the case of virtual packages provided: =========== =========================================== ===================== Attribute Purpose Default =========== =========================================== ===================== ``home`` The installation path for the package ``spec.prefix`` ``command`` An executable command for the package | ``spec.name`` found in | ``.home.bin`` ``headers`` A list of headers provided by the package | All headers searched | recursively in ``.home.include`` ``libs`` A list of libraries provided by the package | ``lib{spec.name}`` searched | recursively in ``.home`` starting | with ``lib``, ``lib64``, then the | rest of ``.home`` =========== =========================================== ===================== Each of these can be customized by implementing the relevant attribute as a ``@property`` in the package's class: .. code-block:: python :linenos: class Foo(Package): ... @property def libs(self): # The library provided by Foo is libMyFoo.so return find_libraries('libMyFoo', root=self.home, recursive=True) A package may also provide a custom implementation of each attribute for the virtual packages it provides by implementing the ``virtualpackagename_attributename`` property in the package's class. The implementation used is the first one found from: #. Specialized virtual: ``Package.virtualpackagename_attributename`` #. Generic package: ``Package.attributename`` #. Default The use of customized attributes is demonstrated in the next example. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Example: Customized attributes for virtual packages ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Consider a package ``foo`` that can optionally provide two virtual packages ``bar`` and ``baz``. When both are enabled the installation tree appears as follows: .. code-block:: console include/foo.h include/bar/bar.h lib64/libFoo.so lib64/libFooBar.so baz/include/baz/baz.h baz/lib/libFooBaz.so The install tree shows that ``foo`` is providing the header ``include/foo.h`` and library ``lib64/libFoo.so`` in it's install prefix. The virtual package ``bar`` is providing ``include/bar/bar.h`` and library ``lib64/libFooBar.so``, also in ``foo``'s install prefix. The ``baz`` package, however, is provided in the ``baz`` subdirectory of ``foo``'s prefix with the ``include/baz/baz.h`` header and ``lib/libFooBaz.so`` library. Such a package could implement the optional attributes as follows: .. code-block:: python :linenos: class Foo(Package): ... variant('bar', default=False, description='Enable the Foo implementation of bar') variant('baz', default=False, description='Enable the Foo implementation of baz') ... provides('bar', when='+bar') provides('baz', when='+baz') .... # Just the foo headers @property def headers(self): return find_headers('foo', root=self.home.include, recursive=False) # Just the foo libraries @property def libs(self): return find_libraries('libFoo', root=self.home, recursive=True) # The header provided by the bar virutal package @property def bar_headers(self): return find_headers('bar/bar.h', root=self.home.include, recursive=False) # The libary provided by the bar virtual package @property def bar_libs(self): return find_libraries('libFooBar', root=sef.home, recursive=True) # The baz virtual package home @property def baz_home(self): return self.prefix.baz # The header provided by the baz virtual package @property def baz_headers(self): return find_headers('baz/baz', root=self.baz_home.include, recursive=False) # The library provided by the baz virtual package @property def baz_libs(self): return find_libraries('libFooBaz', root=self.baz_home, recursive=True) Now consider another package, ``foo-app``, depending on all three: .. code-block:: python :linenos: class FooApp(CMakePackage): ... depends_on('foo') depends_on('bar') depends_on('baz') The resulting spec objects for it's dependencies shows the result of the above attribute implementations: .. code-block:: python # The core headers and libraries of the foo package >>> spec['foo'] foo@1.0%gcc@11.3.1+bar+baz arch=linux-fedora35-haswell >>> spec['foo'].prefix '/opt/spack/linux-fedora35-haswell/gcc-11.3.1/foo-1.0-ca3rczp5omy7dfzoqw4p7oc2yh3u7lt6' # home defaults to the package install prefix without an explicit implementation >>> spec['foo'].home '/opt/spack/linux-fedora35-haswell/gcc-11.3.1/foo-1.0-ca3rczp5omy7dfzoqw4p7oc2yh3u7lt6' # foo headers from the foo prefix >>> spec['foo'].headers HeaderList([ '/opt/spack/linux-fedora35-haswell/gcc-11.3.1/foo-1.0-ca3rczp5omy7dfzoqw4p7oc2yh3u7lt6/include/foo.h', ]) # foo include directories from the foo prefix >>> spec['foo'].headers.directories ['/opt/spack/linux-fedora35-haswell/gcc-11.3.1/foo-1.0-ca3rczp5omy7dfzoqw4p7oc2yh3u7lt6/include'] # foo libraries from the foo prefix >>> spec['foo'].libs LibraryList([ '/opt/spack/linux-fedora35-haswell/gcc-11.3.1/foo-1.0-ca3rczp5omy7dfzoqw4p7oc2yh3u7lt6/lib64/libFoo.so', ]) # foo library directories from the foo prefix >>> spec['foo'].libs.directories ['/opt/spack/linux-fedora35-haswell/gcc-11.3.1/foo-1.0-ca3rczp5omy7dfzoqw4p7oc2yh3u7lt6/lib64'] .. code-block:: python # The virtual bar package in the same prefix as foo # bar resolves to the foo package >>> spec['bar'] foo@1.0%gcc@11.3.1+bar+baz arch=linux-fedora35-haswell >>> spec['bar'].prefix '/opt/spack/linux-fedora35-haswell/gcc-11.3.1/foo-1.0-ca3rczp5omy7dfzoqw4p7oc2yh3u7lt6' # home defaults to the foo prefix without either a Foo.bar_home # or Foo.home implementation >>> spec['bar'].home '/opt/spack/linux-fedora35-haswell/gcc-11.3.1/foo-1.0-ca3rczp5omy7dfzoqw4p7oc2yh3u7lt6' # bar header in the foo prefix >>> spec['bar'].headers HeaderList([ '/opt/spack/linux-fedora35-haswell/gcc-11.3.1/foo-1.0-ca3rczp5omy7dfzoqw4p7oc2yh3u7lt6/include/bar/bar.h' ]) # bar include dirs from the foo prefix >>> spec['bar'].headers.directories ['/opt/spack/linux-fedora35-haswell/gcc-11.3.1/foo-1.0-ca3rczp5omy7dfzoqw4p7oc2yh3u7lt6/include'] # bar library from the foo prefix >>> spec['bar'].libs LibraryList([ '/opt/spack/linux-fedora35-haswell/gcc-11.3.1/foo-1.0-ca3rczp5omy7dfzoqw4p7oc2yh3u7lt6/lib64/libFooBar.so' ]) # bar library directories from the foo prefix >>> spec['bar'].libs.directories ['/opt/spack/linux-fedora35-haswell/gcc-11.3.1/foo-1.0-ca3rczp5omy7dfzoqw4p7oc2yh3u7lt6/lib64'] .. code-block:: python # The virtual baz package in a subdirectory of foo's prefix # baz resolves to the foo package >>> spec['baz'] foo@1.0%gcc@11.3.1+bar+baz arch=linux-fedora35-haswell >>> spec['baz'].prefix '/opt/spack/linux-fedora35-haswell/gcc-11.3.1/foo-1.0-ca3rczp5omy7dfzoqw4p7oc2yh3u7lt6' # baz_home implementation provides the subdirectory inside the foo prefix >>> spec['baz'].home '/opt/spack/linux-fedora35-haswell/gcc-11.3.1/foo-1.0-ca3rczp5omy7dfzoqw4p7oc2yh3u7lt6/baz' # baz headers in the baz subdirectory of the foo prefix >>> spec['baz'].headers HeaderList([ '/opt/spack/linux-fedora35-haswell/gcc-11.3.1/foo-1.0-ca3rczp5omy7dfzoqw4p7oc2yh3u7lt6/baz/include/baz/baz.h' ]) # baz include directories in the baz subdirectory of the foo prefix >>> spec['baz'].headers.directories [ '/opt/spack/linux-fedora35-haswell/gcc-11.3.1/foo-1.0-ca3rczp5omy7dfzoqw4p7oc2yh3u7lt6/baz/include' ] # baz libraries in the baz subdirectory of the foo prefix >>> spec['baz'].libs LibraryList([ '/opt/spack/linux-fedora35-haswell/gcc-11.3.1/foo-1.0-ca3rczp5omy7dfzoqw4p7oc2yh3u7lt6/baz/lib/libFooBaz.so' ]) # baz library directories in the baz subdirectory of the foo porefix >>> spec['baz'].libs.directories [ '/opt/spack/linux-fedora35-haswell/gcc-11.3.1/foo-1.0-ca3rczp5omy7dfzoqw4p7oc2yh3u7lt6/baz/lib' ] .. _abstract-and-concrete: ------------------------- Abstract & concrete specs ------------------------- Now that we've seen how spec constraints can be specified :ref:`on the command line ` and within package definitions, we can talk about how Spack puts all of this information together. When you run this: .. code-block:: console $ spack install mpileaks ^callpath@1.0+debug ^libelf@0.8.11 Spack parses the command line and builds a spec from the description. The spec says that ``mpileaks`` should be built with the ``callpath`` library at 1.0 and with the debug option enabled, and with ``libelf`` version 0.8.11. Spack will also look at the ``depends_on`` calls in all of these packages, and it will build a spec from that. The specs from the command line and the specs built from package descriptions are then combined, and the constraints are checked against each other to make sure they're satisfiable. What we have after this is done is called an *abstract spec*. An abstract spec is partially specified. In other words, it could describe more than one build of a package. Spack does this to make things easier on the user: they should only have to specify as much of the package spec as they care about. Here's an example partial spec DAG, based on the constraints above: .. code-block:: none mpileaks ^callpath@1.0+debug ^dyninst ^libdwarf ^libelf@0.8.11 ^mpi .. graphviz:: digraph { mpileaks -> mpi mpileaks -> "callpath@1.0+debug" -> mpi "callpath@1.0+debug" -> dyninst dyninst -> libdwarf -> "libelf@0.8.11" dyninst -> "libelf@0.8.11" } This diagram shows a spec DAG output as a tree, where successive levels of indentation represent a depends-on relationship. In the above DAG, we can see some packages annotated with their constraints, and some packages with no annotations at all. When there are no annotations, it means the user doesn't care what configuration of that package is built, just so long as it works. ^^^^^^^^^^^^^^ Concretization ^^^^^^^^^^^^^^ An abstract spec is useful for the user, but you can't install an abstract spec. Spack has to take the abstract spec and "fill in" the remaining unspecified parts in order to install. This process is called **concretization**. Concretization happens in between the time the user runs ``spack install`` and the time the ``install()`` method is called. The concretized version of the spec above might look like this: .. code-block:: none mpileaks@2.3%gcc@4.7.3 arch=linux-debian7-x86_64 ^callpath@1.0%gcc@4.7.3+debug arch=linux-debian7-x86_64 ^dyninst@8.1.2%gcc@4.7.3 arch=linux-debian7-x86_64 ^libdwarf@20130729%gcc@4.7.3 arch=linux-debian7-x86_64 ^libelf@0.8.11%gcc@4.7.3 arch=linux-debian7-x86_64 ^mpich@3.0.4%gcc@4.7.3 arch=linux-debian7-x86_64 .. graphviz:: digraph { "mpileaks@2.3\n%gcc@4.7.3\n arch=linux-debian7-x86_64" -> "mpich@3.0.4\n%gcc@4.7.3\n arch=linux-debian7-x86_64" "mpileaks@2.3\n%gcc@4.7.3\n arch=linux-debian7-x86_64" -> "callpath@1.0\n%gcc@4.7.3+debug\n arch=linux-debian7-x86_64" -> "mpich@3.0.4\n%gcc@4.7.3\n arch=linux-debian7-x86_64" "callpath@1.0\n%gcc@4.7.3+debug\n arch=linux-debian7-x86_64" -> "dyninst@8.1.2\n%gcc@4.7.3\n arch=linux-debian7-x86_64" "dyninst@8.1.2\n%gcc@4.7.3\n arch=linux-debian7-x86_64" -> "libdwarf@20130729\n%gcc@4.7.3\n arch=linux-debian7-x86_64" -> "libelf@0.8.11\n%gcc@4.7.3\n arch=linux-debian7-x86_64" "dyninst@8.1.2\n%gcc@4.7.3\n arch=linux-debian7-x86_64" -> "libelf@0.8.11\n%gcc@4.7.3\n arch=linux-debian7-x86_64" } Here, all versions, compilers, and platforms are filled in, and there is a single version (no version ranges) for each package. All decisions about configuration have been made, and only after this point will Spack call the ``install()`` method for your package. Concretization in Spack is based on certain selection policies that tell Spack how to select, e.g., a version, when one is not specified explicitly. Concretization policies are discussed in more detail in :ref:`configuration`. Sites using Spack can customize them to match the preferences of their own users. .. _cmd-spack-spec: ^^^^^^^^^^^^^^ ``spack spec`` ^^^^^^^^^^^^^^ For an arbitrary spec, you can see the result of concretization by running ``spack spec``. For example: .. code-block:: console $ spack spec dyninst@8.0.1 dyninst@8.0.1 ^libdwarf ^libelf dyninst@8.0.1%gcc@4.7.3 arch=linux-debian7-x86_64 ^libdwarf@20130729%gcc@4.7.3 arch=linux-debian7-x86_64 ^libelf@0.8.13%gcc@4.7.3 arch=linux-debian7-x86_64 This is useful when you want to know exactly what Spack will do when you ask for a particular spec. .. _concretization-policies: ^^^^^^^^^^^^^^^^^^^^^^^^^^^ ``Concretization Policies`` ^^^^^^^^^^^^^^^^^^^^^^^^^^^ A user may have certain preferences for how packages should be concretized on their system. For example, one user may prefer packages built with OpenMPI and the Intel compiler. Another user may prefer packages be built with MVAPICH and GCC. See the :ref:`package-preferences` section for more details. .. _group_when_spec: ---------------------------- Common ``when=`` constraints ---------------------------- In case a package needs many directives to share the whole ``when=`` argument, or just part of it, Spack allows you to group the common part under a context manager: .. code-block:: python class Gcc(AutotoolsPackage): with when('+nvptx'): depends_on('cuda') conflicts('@:6', msg='NVPTX only supported in gcc 7 and above') conflicts('languages=ada') conflicts('languages=brig') conflicts('languages=go') The snippet above is equivalent to the more verbose: .. code-block:: python class Gcc(AutotoolsPackage): depends_on('cuda', when='+nvptx') conflicts('@:6', when='+nvptx', msg='NVPTX only supported in gcc 7 and above') conflicts('languages=ada', when='+nvptx') conflicts('languages=brig', when='+nvptx') conflicts('languages=go', when='+nvptx') Constraints stemming from the context are added to what is explicitly present in the ``when=`` argument of a directive, so: .. code-block:: python with when('+elpa'): depends_on('elpa+openmp', when='+openmp') is equivalent to: .. code-block:: python depends_on('elpa+openmp', when='+openmp+elpa') Constraints from nested context managers are also combined together, but they are rarely needed or recommended. .. _install-method: ------------------ Conflicting Specs ------------------ Suppose a user needs to install package C, which depends on packages A and B. Package A builds a library with a Python2 extension, and package B builds a library with a Python3 extension. Packages A and B cannot be loaded together in the same Python runtime: .. code-block:: python class A(Package): variant('python', default=True, 'enable python bindings') depends_on('python@2.7', when='+python') def install(self, spec, prefix): # do whatever is necessary to enable/disable python # bindings according to variant class B(Package): variant('python', default=True, 'enable python bindings') depends_on('python@3.2:', when='+python') def install(self, spec, prefix): # do whatever is necessary to enable/disable python # bindings according to variant Package C needs to use the libraries from packages A and B, but does not need either of the Python extensions. In this case, package C should simply depend on the ``~python`` variant of A and B: .. code-block:: python class C(Package): depends_on('A~python') depends_on('B~python') This may require that A or B be built twice, if the user wishes to use the Python extensions provided by them: once for ``+python`` and once for ``~python``. Other than using a little extra disk space, that solution has no serious problems. .. _installation_process: -------------------------------- Overriding build system defaults -------------------------------- .. note:: If you code a single class in ``package.py`` all the functions shown in the table below can be implemented with the same signature on the ``*Package`` instead of the corresponding builder. Most of the time the default implementation of methods or attributes in build system base classes is what a packager needs, and just a very few entities need to be overwritten. Typically we just need to override methods like ``configure_args``: .. code-block:: python def configure_args(self): args = ["--enable-cxx"] + self.enable_or_disable("libs") if "libs=static" in self.spec: args.append("--with-pic") return args The actual set of entities available for overriding in ``package.py`` depend on the build system. The build systems currently supported by Spack are: +----------------------------------------------------------+----------------------------------+ | **API docs** | **Description** | +==========================================================+==================================+ | :class:`~spack.build_systems.generic` | Generic build system without any | | | base implementation | +----------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.makefile` | Specialized build system for | | | software built invoking | | | hand-written Makefiles | +----------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.autotools` | Specialized build system for | | | software built using | | | GNU Autotools | +----------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.cmake` | Specialized build system for | | | software built using CMake | +----------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.maven` | Specialized build system for | | | software built using Maven | +----------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.meson` | Specialized build system for | | | software built using Meson | +----------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.nmake` | Specialized build system for | | | software built using NMake | +----------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.qmake` | Specialized build system for | | | software built using QMake | +----------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.scons` | Specialized build system for | | | software built using SCons | +----------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.waf` | Specialized build system for | | | software built using Waf | +----------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.r` | Specialized build system for | | | R extensions | +----------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.octave` | Specialized build system for | | | Octave packages | +----------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.python` | Specialized build system for | | | Python extensions | +----------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.perl` | Specialized build system for | | | Perl extensions | +----------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.ruby` | Specialized build system for | | | Ruby extensions | +----------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.intel` | Specialized build system for | | | licensed Intel software | +----------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.oneapi` | Specialized build system for | | | Intel onaAPI software | +----------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.aspell_dict` | Specialized build system for | | | Aspell dictionaries | +----------------------------------------------------------+----------------------------------+ .. note:: Choice of the appropriate base class for a package In most cases packagers don't have to worry about the selection of the right base class for a package, as ``spack create`` will make the appropriate choice on their behalf. In those rare cases where manual intervention is needed we need to stress that a package base class depends on the *build system* being used, not the language of the package. For example, a Python extension installed with CMake would ``extends('python')`` and subclass from :class:`~spack.build_systems.cmake.CMakePackage`. ^^^^^^^^^^^^^^^^^^^^^^^^^^ Overriding builder methods ^^^^^^^^^^^^^^^^^^^^^^^^^^ Build-system "phases" have default implementations that fit most of the common cases: .. literalinclude:: _spack_root/lib/spack/spack/build_systems/autotools.py :pyobject: AutotoolsBuilder.configure :linenos: It is usually sufficient for a packager to override a few build system specific helper methods or attributes to provide, for instance, configure arguments: .. literalinclude:: _spack_root/var/spack/repos/builtin/packages/m4/package.py :pyobject: M4.configure_args :linenos: Each specific build system has a list of attributes and methods that can be overridden to fine-tune the installation of a package without overriding an entire phase. To have more information on them the place to go is the API docs of the :py:mod:`~.spack.build_systems` module. ^^^^^^^^^^^^^^^^^^^^^^^^^^ Overriding an entire phase ^^^^^^^^^^^^^^^^^^^^^^^^^^ Sometimes it is necessary to override an entire phase. If the ``package.py`` contains a single class recipe, see :ref:`package_class_structure`, then the signature for a phase is: .. code-block:: python class Openjpeg(CMakePackage): def install(self, spec, prefix): ... regardless of the build system. The arguments for the phase are: ``self`` This is the package object, which extends ``CMakePackage``. For API docs on Package objects, see :py:class:`Package `. ``spec`` This is the concrete spec object created by Spack from an abstract spec supplied by the user. It describes what should be installed. It will be of type :py:class:`Spec `. ``prefix`` This is the path that your install method should copy build targets into. It acts like a string, but it's actually its own special type, :py:class:`Prefix `. The arguments ``spec`` and ``prefix`` are passed only for convenience, as they always correspond to ``self.spec`` and ``self.spec.prefix`` respectively. If the ``package.py`` encodes builders explicitly, the signature for a phase changes slightly: .. code-block:: python class CMakeBuilder(spack.build_systems.cmake.CMakeBuilder): def install(self, pkg, spec, prefix): ... In this case the package is passed as the second argument, and ``self`` is the builder instance. .. _multiple_build_systems: ^^^^^^^^^^^^^^^^^^^^^^ Multiple build systems ^^^^^^^^^^^^^^^^^^^^^^ There are cases where a software actively supports two build systems, or changes build systems as it evolves, or needs different build systems on different platforms. Spack allows dealing with these cases natively, if a recipe is written using builders explicitly. For instance, software that supports two build systems unconditionally should derive from both ``*Package`` base classes, and declare the possible use of multiple build systems using a directive: .. code-block:: python class ArpackNg(CMakePackage, AutotoolsPackage): build_system("cmake", "autotools", default="cmake") In this case the software can be built with both ``autotools`` and ``cmake``. Since the package supports multiple build systems, it is necessary to declare which one is the default. The ``package.py`` will likely contain some overriding of default builder methods: .. code-block:: python class CMakeBuilder(spack.build_systems.cmake.CMakeBuilder): def cmake_args(self): pass class Autotoolsbuilder(spack.build_systems.autotools.AutotoolsBuilder): def configure_args(self): pass In more complex cases it might happen that the build system changes according to certain conditions, for instance across versions. That can be expressed with conditional variant values: .. code-block:: python class ArpackNg(CMakePackage, AutotoolsPackage): build_system( conditional("cmake", when="@0.64:"), conditional("autotools", when="@:0.63"), default="cmake", ) In the example the directive impose a change from ``Autotools`` to ``CMake`` going from ``v0.63`` to ``v0.64``. ^^^^^^^^^^^^^^^^^^ Mixin base classes ^^^^^^^^^^^^^^^^^^ Besides build systems, there are other cases where common metadata and behavior can be extracted and reused by many packages. For instance, packages that depend on ``Cuda`` or ``Rocm``, share common dependencies and constraints. To factor these attributes into a single place, Spack provides a few mixin classes in the ``spack.build_systems`` module: +---------------------------------------------------------------+----------------------------------+ | **API docs** | **Description** | +===============================================================+==================================+ | :class:`~spack.build_systems.cuda.CudaPackage` | A helper class for packages that | | | use CUDA | +---------------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.rocm.ROCmPackage` | A helper class for packages that | | | use ROCm | +---------------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.gnu.GNUMirrorPackage` | A helper class for GNU packages | +---------------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.python.PythonExtension` | A helper class for Python | | | extensions | +---------------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.sourceforge.SourceforgePackage` | A helper class for packages | | | from sourceforge.org | +---------------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.sourceware.SourcewarePackage` | A helper class for packages | | | from sourceware.org | +---------------------------------------------------------------+----------------------------------+ | :class:`~spack.build_systems.xorg.XorgPackage` | A helper class for x.org | | | packages | +---------------------------------------------------------------+----------------------------------+ These classes should be used by adding them to the inheritance tree of the package that needs them, for instance: .. code-block:: python class Cp2k(MakefilePackage, CudaPackage): """CP2K is a quantum chemistry and solid state physics software package that can perform atomistic simulations of solid state, liquid, molecular, periodic, material, crystal, and biological systems """ In the example above ``Cp2k`` inherits all the conflicts and variants that ``CudaPackage`` defines. .. _install-environment: ----------------------- The build environment ----------------------- In general, you should not have to do much differently in your install method than you would when installing a package on the command line. In fact, you may need to do *less* than you would on the command line. Spack tries to set environment variables and modify compiler calls so that it *appears* to the build system that you're building with a standard system install of everything. Obviously that's not going to cover *all* build systems, but it should make it easy to port packages to Spack if they use a standard build system. Usually with autotools or cmake, building and installing is easy. With builds that use custom Makefiles, you may need to add logic to modify the makefiles. The remainder of the section covers the way Spack's build environment works. ^^^^^^^^^^^^^^^^^^^^^ Forking ``install()`` ^^^^^^^^^^^^^^^^^^^^^ To give packagers free reign over their install environment, Spack forks a new process each time it invokes a package's ``install()`` method. This allows packages to have a sandboxed build environment, without impacting the environments ofother jobs that the main Spack process runs. Packages are free to change the environment or to modify Spack internals, because each ``install()`` call has its own dedicated process. ^^^^^^^^^^^^^^^^^^^^^ Environment variables ^^^^^^^^^^^^^^^^^^^^^ Spack sets a number of standard environment variables that serve two purposes: #. Make build systems use Spack's compiler wrappers for their builds. #. Allow build systems to find dependencies more easily The Compiler environment variables that Spack sets are: ============ =============================== Variable Purpose ============ =============================== ``CC`` C compiler ``CXX`` C++ compiler ``F77`` Fortran 77 compiler ``FC`` Fortran 90 and above compiler ============ =============================== Spack sets these variables so that they point to *compiler wrappers*. These are covered in :ref:`their own section ` below. All of these are standard variables respected by most build systems. If your project uses ``Autotools`` or ``CMake``, then it should pick them up automatically when you run ``configure`` or ``cmake`` in the ``install()`` function. Many traditional builds using GNU Make and BSD make also respect these variables, so they may work with these systems. If your build system does *not* automatically pick these variables up from the environment, then you can simply pass them on the command line or use a patch as part of your build process to get the correct compilers into the project's build system. There are also some file editing commands you can use -- these are described later in the `section on file manipulation `_. In addition to the compiler variables, these variables are set before entering ``install()`` so that packages can locate dependencies easily: ===================== ==================================================== ``PATH`` Set to point to ``/bin`` directories of dependencies ``CMAKE_PREFIX_PATH`` Path to dependency prefixes for CMake ``PKG_CONFIG_PATH`` Path to any pkgconfig directories for dependencies ``PYTHONPATH`` Path to site-packages dir of any python dependencies ===================== ==================================================== ``PATH`` is set up to point to dependencies ``/bin`` directories so that you can use tools installed by dependency packages at build time. For example, ``$MPICH_ROOT/bin/mpicc`` is frequently used by dependencies of ``mpich``. ``CMAKE_PREFIX_PATH`` contains a colon-separated list of prefixes where ``cmake`` will search for dependency libraries and headers. This causes all standard CMake find commands to look in the paths of your dependencies, so you *do not* have to manually specify arguments like ``-DDEPENDENCY_DIR=/path/to/dependency`` to ``cmake``. More on this is `in the CMake documentation `_. ``PKG_CONFIG_PATH`` is for packages that attempt to discover dependencies using the GNU ``pkg-config`` tool. It is similar to ``CMAKE_PREFIX_PATH`` in that it allows a build to automatically discover its dependencies. If you want to see the environment that a package will build with, or if you want to run commands in that environment to test them out, you can use the :ref:`cmd-spack-build-env` command, documented below. ^^^^^^^^^^^^^^^^^^^^^ Failing the build ^^^^^^^^^^^^^^^^^^^^^ Sometimes you don't want a package to successfully install unless some condition is true. You can explicitly cause the build to fail from ``install()`` by raising an ``InstallError``, for example: .. code-block:: python if spec.architecture.startswith('darwin'): raise InstallError('This package does not build on Mac OS X!') .. _shell-wrappers: ^^^^^^^^^^^^^^^^^^^^^^^ Shell command functions ^^^^^^^^^^^^^^^^^^^^^^^ Recall the install method from ``libelf``: .. literalinclude:: _spack_root/var/spack/repos/builtin/packages/libelf/package.py :pyobject: Libelf.install :linenos: Normally in Python, you'd have to write something like this in order to execute shell commands: .. code-block:: python import subprocess subprocess.check_call('configure', '--prefix={0}'.format(prefix)) We've tried to make this a bit easier by providing callable wrapper objects for some shell commands. By default, ``configure``, ``cmake``, and ``make`` wrappers are are provided, so you can call them more naturally in your package files. If you need other commands, you can use ``which`` to get them: .. code-block:: python sed = which('sed') sed('s/foo/bar/', filename) The ``which`` function will search the ``PATH`` for the application. Callable wrappers also allow spack to provide some special features. For example, in Spack, ``make`` is parallel by default, and Spack figures out the number of cores on your machine and passes an appropriate value for ``-j`` when it calls ``make`` (see the ``parallel`` `package attribute `). In a package file, you can supply a keyword argument, ``parallel=False``, to the ``make`` wrapper to disable parallel make. In the ``libelf`` package, this allows us to avoid race conditions in the library's build system. ^^^^^^^^^^^^^^ Compiler flags ^^^^^^^^^^^^^^ Compiler flags set by the user through the Spec object can be passed to the build in one of three ways. By default, the build environment injects these flags directly into the compiler commands using Spack's compiler wrappers. In cases where the build system requires knowledge of the compiler flags, they can be registered with the build system by alternatively passing them through environment variables or as build system arguments. The flag_handler method can be used to change this behavior. Packages can override the flag_handler method with one of three built-in flag_handlers. The built-in flag_handlers are named ``inject_flags``, ``env_flags``, and ``build_system_flags``. The ``inject_flags`` method is the default. The ``env_flags`` method puts all of the flags into the environment variables that ``make`` uses as implicit variables ('CFLAGS', 'CXXFLAGS', etc.). The ``build_system_flags`` method adds the flags as arguments to the invocation of ``configure`` or ``cmake``, respectively. .. warning:: Passing compiler flags using build system arguments is only supported for CMake and Autotools packages. Individual packages may also differ in whether they properly respect these arguments. Individual packages may also define their own ``flag_handler`` methods. The ``flag_handler`` method takes the package instance (``self``), the name of the flag, and a list of the values of the flag. It will be called on each of the six compiler flags supported in Spack. It should return a triple of ``(injf, envf, bsf)`` where ``injf`` is a list of flags to inject via the Spack compiler wrappers, ``envf`` is a list of flags to set in the appropriate environment variables, and ``bsf`` is a list of flags to pass to the build system as arguments. .. warning:: Passing a non-empty list of flags to ``bsf`` for a build system that does not support build system arguments will result in an error. Here are the definitions of the three built-in flag handlers: .. code-block:: python def inject_flags(pkg, name, flags): return (flags, None, None) def env_flags(pkg, name, flags): return (None, flags, None) def build_system_flags(pkg, name, flags): return (None, None, flags) .. note:: Returning ``[]`` and ``None`` are equivalent in a ``flag_handler`` method. Packages can override the default behavior either by specifying one of the built-in flag handlers, .. code-block:: python flag_handler = env_flags or by implementing the flag_handler method. Suppose for a package ``Foo`` we need to pass ``cflags``, ``cxxflags``, and ``cppflags`` through the environment, the rest of the flags through compiler wrapper injection, and we need to add ``-lbar`` to ``ldlibs``. The following flag handler method accomplishes that. .. code-block:: python def flag_handler(self, name, flags): if name in ['cflags', 'cxxflags', 'cppflags']: return (None, flags, None) elif name == 'ldlibs': flags.append('-lbar') return (flags, None, None) Because these methods can pass values through environment variables, it is important not to override these variables unnecessarily (E.g. setting ``env['CFLAGS']``) in other package methods when using non-default flag handlers. In the ``setup_environment`` and ``setup_dependent_environment`` methods, use the ``append_flags`` method of the ``EnvironmentModifications`` class to append values to a list of flags whenever the flag handler is ``env_flags``. If the package passes flags through the environment or the build system manually (in the install method, for example), we recommend using the default flag handler, or removing manual references and implementing a custom flag handler method that adds the desired flags to export as environment variables or pass to the build system. Manual flag passing is likely to interfere with the ``env_flags`` and ``build_system_flags`` methods. In rare circumstances such as compiling and running small unit tests, a package developer may need to know what are the appropriate compiler flags to enable features like ``OpenMP``, ``c++11``, ``c++14`` and alike. To that end the compiler classes in ``spack`` implement the following **properties**: ``openmp_flag``, ``cxx98_flag``, ``cxx11_flag``, ``cxx14_flag``, and ``cxx17_flag``, which can be accessed in a package by ``self.compiler.cxx11_flag`` and alike. Note that the implementation is such that if a given compiler version does not support this feature, an error will be produced. Therefore package developers can also use these properties to assert that a compiler supports the requested feature. This is handy when a package supports additional variants like .. code-block:: python variant('openmp', default=True, description="Enable OpenMP support.") .. _blas_lapack_scalapack: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Blas, Lapack and ScaLapack libraries ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Multiple packages provide implementations of ``Blas``, ``Lapack`` and ``ScaLapack`` routines. The names of the resulting static and/or shared libraries differ from package to package. In order to make the ``install()`` method independent of the choice of ``Blas`` implementation, each package which provides it implements ``@property def blas_libs(self):`` to return an object of `LibraryList `_ type which simplifies usage of a set of libraries. The same applies to packages which provide ``Lapack`` and ``ScaLapack``. Package developers are requested to use this interface. Common usage cases are: 1. Space separated list of full paths .. code-block:: python lapack_blas = spec['lapack'].libs + spec['blas'].libs options.append( '--with-blas-lapack-lib={0}'.format(lapack_blas.joined()) ) 2. Names of libraries and directories which contain them .. code-block:: python blas = spec['blas'].libs options.extend([ '-DBLAS_LIBRARY_NAMES={0}'.format(';'.join(blas.names)), '-DBLAS_LIBRARY_DIRS={0}'.format(';'.join(blas.directories)) ]) 3. Search and link flags .. code-block:: python math_libs = spec['scalapack'].libs + spec['lapack'].libs + spec['blas'].libs options.append( '-DMATH_LIBS:STRING={0}'.format(math_libs.ld_flags) ) For more information, see documentation of `LibraryList `_ class. .. _prefix-objects: ^^^^^^^^^^^^^^^^^^^^^ Prefix objects ^^^^^^^^^^^^^^^^^^^^^ Spack passes the ``prefix`` parameter to the install method so that you can pass it to ``configure``, ``cmake``, or some other installer, e.g.: .. code-block:: python configure('--prefix={0}'.format(prefix)) For the most part, prefix objects behave exactly like strings. For packages that do not have their own install target, or for those that implement it poorly (like ``libdwarf``), you may need to manually copy things into particular directories under the prefix. For this, you can refer to standard subdirectories without having to construct paths yourself, e.g.: .. code-block:: python def install(self, spec, prefix): mkdirp(prefix.bin) install('foo-tool', prefix.bin) mkdirp(prefix.include) install('foo.h', prefix.include) mkdirp(prefix.lib) install('libfoo.a', prefix.lib) Attributes of this object are created on the fly when you request them, so any of the following will work: ====================== ======================= Prefix Attribute Location ====================== ======================= ``prefix.bin`` ``$prefix/bin`` ``prefix.lib64`` ``$prefix/lib64`` ``prefix.share.man`` ``$prefix/share/man`` ``prefix.foo.bar.baz`` ``$prefix/foo/bar/baz`` ====================== ======================= Of course, this only works if your file or directory is a valid Python variable name. If your file or directory contains dashes or dots, use ``join`` instead: .. code-block:: python prefix.lib.join('libz.a') .. _spec-objects: ------------ Spec objects ------------ When ``install`` is called, most parts of the build process are set up for you. The correct version's tarball has been downloaded and expanded. Environment variables like ``CC`` and ``CXX`` are set to point to the correct compiler and version. An install prefix has already been selected and passed in as ``prefix``. In most cases this is all you need to get ``configure``, ``cmake``, or another install working correctly. There will be times when you need to know more about the build configuration. For example, some software requires that you pass special parameters to ``configure``, like ``--with-libelf=/path/to/libelf`` or ``--with-mpich``. You might also need to supply special compiler flags depending on the compiler. All of this information is available in the spec. ^^^^^^^^^^^^^^^^^^^^^^^^ Testing spec constraints ^^^^^^^^^^^^^^^^^^^^^^^^ You can test whether your spec is configured a certain way by using the ``satisfies`` method. For example, if you want to check whether the package's version is in a particular range, you can use specs to do that, e.g.: .. code-block:: python configure_args = [ '--prefix={0}'.format(prefix) ] if spec.satisfies('@1.2:1.4'): configure_args.append("CXXFLAGS='-DWITH_FEATURE'") configure(*configure_args) This works for compilers, too: .. code-block:: python if spec.satisfies('%gcc'): configure_args.append('CXXFLAGS="-g3 -O3"') if spec.satisfies('%intel'): configure_args.append('CXXFLAGS="-xSSE2 -fast"') Or for combinations of spec constraints: .. code-block:: python if spec.satisfies('@1.2%intel'): tty.error("Version 1.2 breaks when using Intel compiler!") You can also do similar satisfaction tests for dependencies: .. code-block:: python if spec.satisfies('^dyninst@8.0'): configure_args.append('CXXFLAGS=-DSPECIAL_DYNINST_FEATURE') This could allow you to easily work around a bug in a particular dependency version. You can use ``satisfies()`` to test for particular dependencies, e.g. ``foo.satisfies('^openmpi@1.2')`` or ``foo.satisfies('^mpich')``, or you can use Python's built-in ``in`` operator: .. code-block:: python if 'libelf' in spec: print "this package depends on libelf" This is useful for virtual dependencies, as you can easily see what implementation was selected for this build: .. code-block:: python if 'openmpi' in spec: configure_args.append('--with-openmpi') elif 'mpich' in spec: configure_args.append('--with-mpich') elif 'mvapich' in spec: configure_args.append('--with-mvapich') It's also a bit more concise than satisfies. The difference between the two functions is that ``satisfies()`` tests whether spec constraints overlap at all, while ``in`` tests whether a spec or any of its dependencies satisfy the provided spec. ^^^^^^^^^^^^^^^^^^^^^^^ Architecture specifiers ^^^^^^^^^^^^^^^^^^^^^^^ As mentioned in :ref:`support-for-microarchitectures` each node in a concretized spec object has an architecture attribute which is a triplet of ``platform``, ``os`` and ``target``. Each of these three items can be queried to take decisions when configuring, building or installing a package. """""""""""""""""""""""""""""""""""""""""""""" Querying the platform and the operating system """""""""""""""""""""""""""""""""""""""""""""" Sometimes the actions to be taken to install a package might differ depending on the platform we are installing for. If that is the case we can use conditionals: .. code-block:: python if spec.platform == 'darwin': # Actions that are specific to Darwin args.append('--darwin-specific-flag') and branch based on the current spec platform. If we need to make a package directive conditional on the platform we can instead employ the usual spec syntax and pass the corresponding constraint to the appropriate argument of that directive: .. code-block:: python class Libnl(AutotoolsPackage): conflicts('platform=darwin', msg='libnl requires FreeBSD or Linux') Similar considerations are also valid for the ``os`` part of a spec's architecture. For instance: .. code-block:: python class Glib(AutotoolsPackage) patch('old-kernels.patch', when='os=centos6') will apply the patch only when the operating system is Centos 6. .. note:: Even though experienced Python programmers might recognize that there are other ways to retrieve information on the platform: .. code-block:: python if sys.platform == 'darwin': # Actions that are specific to Darwin args.append('--darwin-specific-flag') querying the spec architecture's platform should be considered the preferred. The key difference is that a query on ``sys.platform``, or anything similar, is always bound to the host on which the interpreter running Spack is located and as such it won't work correctly in environments where cross-compilation is required. """"""""""""""""""""""""""""""""""""" Querying the target microarchitecture """"""""""""""""""""""""""""""""""""" The third item of the architecture tuple is the ``target`` which abstracts the information on the CPU microarchitecture. A list of all the targets known to Spack can be obtained via the command line: .. command-output:: spack arch --known-targets Within directives each of the names above can be used to match a particular target: .. code-block:: python class Julia(Package): # This patch is only applied on icelake microarchitectures patch("icelake.patch", when="target=icelake") It's also possible to select all the architectures belonging to the same family using an open range: .. code-block:: python class Julia(Package): # This patch is applied on all x86_64 microarchitectures. # The trailing colon that denotes an open range of targets patch("generic_x86_64.patch", when="target=x86_64:") in a way that resembles what was shown in :ref:`versions-and-fetching` for versions. Where ``target`` objects really shine though is when they are used in methods called at configure, build or install time. In that case we can test targets for supported features, for instance: .. code-block:: python if 'avx512' in spec.target: args.append('--with-avx512') The snippet above will append the ``--with-avx512`` item to a list of arguments only if the corresponding feature is supported by the current target. Sometimes we need to take different actions based on the architecture family and not on the specific microarchitecture. In those cases we can check the ``family`` attribute: .. code-block:: python if spec.target.family == 'ppc64le': args.append('--enable-power') Possible values for the ``family`` attribute are displayed by ``spack arch --known-targets`` under the "Generic architectures (families)" header. Finally it's possible to perform actions based on whether the current microarchitecture is compatible with a known one: .. code-block:: python if spec.target > 'haswell': args.append('--needs-at-least-haswell') The snippet above will add an item to a list of configure options only if the current architecture is a superset of ``haswell`` or, said otherwise, only if the current architecture is a later microarchitecture still compatible with ``haswell``. .. admonition:: Using Spack on unknown microarchitectures If Spack is used on an unknown microarchitecture it will try to perform a best match of the features it detects and will select the closest microarchitecture it has information for. In case nothing matches, it will create on the fly a new generic architecture. This is done to allow users to still be able to use Spack for their work. The software built won't be probably as optimized as it could but just as you need a newer compiler to build for newer architectures, you may need newer versions of Spack for new architectures to be correctly labeled. ^^^^^^^^^^^^^^^^^^^^^^ Accessing Dependencies ^^^^^^^^^^^^^^^^^^^^^^ You may need to get at some file or binary that's in the installation prefix of one of your dependencies. You can do that by sub-scripting the spec: .. code-block:: python spec['mpi'] The value in the brackets needs to be some package name, and spec needs to depend on that package, or the operation will fail. For example, the above code will fail if the ``spec`` doesn't depend on ``mpi``. The value returned is itself just another ``Spec`` object, so you can do all the same things you would do with the package's own spec: .. code-block:: python spec['mpi'].prefix.bin spec['mpi'].version .. _multimethods: ^^^^^^^^^^^^^^^^^^^^^^^^^^ Multimethods and ``@when`` ^^^^^^^^^^^^^^^^^^^^^^^^^^ Spack allows you to make multiple versions of instance functions in packages, based on whether the package's spec satisfies particular criteria. The ``@when`` annotation lets packages declare multiple versions of methods like ``install()`` that depend on the package's spec. For example: .. code-block:: python class SomePackage(Package): ... def install(self, prefix): # Do default install @when('arch=chaos_5_x86_64_ib') def install(self, prefix): # This will be executed instead of the default install if # the package's sys_type() is chaos_5_x86_64_ib. @when('arch=linux-debian7-x86_64') def install(self, prefix): # This will be executed if the package's sys_type() is # linux-debian7-x86_64. In the above code there are three versions of ``install()``, two of which are specialized for particular platforms. The version that is called depends on the architecture of the package spec. Note that this works for methods other than install, as well. So, if you only have part of the install that is platform specific, you could do something more like this: .. code-block:: python class SomePackage(Package): ... # virtual dependence on MPI. # could resolve to mpich, mpich2, OpenMPI depends_on('mpi') def setup(self): # do nothing in the default case pass @when('^openmpi') def setup(self): # do something special when this is built with OpenMPI for # its MPI implementations. def install(self, prefix): # Do common install stuff self.setup() # Do more common install stuff You can write multiple ``@when`` specs that satisfy the package's spec, for example: .. code-block:: python class SomePackage(Package): ... depends_on('mpi') def setup_mpi(self): # the default, called when no @when specs match pass @when('^mpi@3:') def setup_mpi(self): # this will be called when mpi is version 3 or higher pass @when('^mpi@2:') def setup_mpi(self): # this will be called when mpi is version 2 or higher pass @when('^mpi@1:') def setup_mpi(self): # this will be called when mpi is version 1 or higher pass In situations like this, the first matching spec, in declaration order will be called. As before, if no ``@when`` spec matches, the default method (the one without the ``@when`` decorator) will be called. .. warning:: The default version of decorated methods must **always** come first. Otherwise it will override all of the platform-specific versions. There's not much we can do to get around this because of the way decorators work. .. _compiler-wrappers: --------------------- Compiler wrappers --------------------- As mentioned, ``CC``, ``CXX``, ``F77``, and ``FC`` are set to point to Spack's compiler wrappers. These are simply called ``cc``, ``c++``, ``f77``, and ``f90``, and they live in ``$SPACK_ROOT/lib/spack/env``. ``$SPACK_ROOT/lib/spack/env`` is added first in the ``PATH`` environment variable when ``install()`` runs so that system compilers are not picked up instead. All of these compiler wrappers point to a single compiler wrapper script that figures out which *real* compiler it should be building with. This comes either from spec `concretization `_ or from a user explicitly asking for a particular compiler using, e.g., ``%intel`` on the command line. In addition to invoking the right compiler, the compiler wrappers add flags to the compile line so that dependencies can be easily found. These flags are added for each dependency, if they exist: * Compile-time library search paths: ``-L$dep_prefix/lib``, ``-L$dep_prefix/lib64`` * Runtime library search paths (RPATHs): ``$rpath_flag$dep_prefix/lib``, ``$rpath_flag$dep_prefix/lib64`` * Include search paths: ``-I$dep_prefix/include`` An example of this would be the ``libdwarf`` build, which has one dependency: ``libelf``. Every call to ``cc`` in the ``libdwarf`` build will have ``-I$LIBELF_PREFIX/include``, ``-L$LIBELF_PREFIX/lib``, and ``$rpath_flag$LIBELF_PREFIX/lib`` inserted on the command line. This is done transparently to the project's build system, which will just think it's using a system where ``libelf`` is readily available. Because of this, you **do not** have to insert extra ``-I``, ``-L``, etc. on the command line. Another useful consequence of this is that you often do *not* have to add extra parameters on the ``configure`` line to get autotools to find dependencies. The ``libdwarf`` install method just calls configure like this: .. code-block:: python configure("--prefix=" + prefix) Because of the ``-L`` and ``-I`` arguments, configure will successfully find ``libdwarf.h`` and ``libdwarf.so``, without the packager having to provide ``--with-libdwarf=/path/to/libdwarf`` on the command line. .. note:: For most compilers, ``$rpath_flag`` is ``-Wl,-rpath,``. However, NAG passes its flags to GCC instead of passing them directly to the linker. Therefore, its ``$rpath_flag`` is doubly wrapped: ``-Wl,-Wl,,-rpath,``. ``$rpath_flag`` can be overridden on a compiler specific basis in ``lib/spack/spack/compilers/$compiler.py``. The compiler wrappers also pass the compiler flags specified by the user from the command line (``cflags``, ``cxxflags``, ``fflags``, ``cppflags``, ``ldflags``, and/or ``ldlibs``). They do not override the canonical autotools flags with the same names (but in ALL-CAPS) that may be passed into the build by particularly challenging package scripts. --------------------- MPI support in Spack --------------------- It is common for high performance computing software/packages to use the Message Passing Interface ( ``MPI``). As a result of conretization, a given package can be built using different implementations of MPI such as ``Openmpi``, ``MPICH`` or ``IntelMPI``. That is, when your package declares that it ``depends_on('mpi')``, it can be built with any of these ``mpi`` implementations. In some scenarios, to configure a package, one has to provide it with appropriate MPI compiler wrappers such as ``mpicc``, ``mpic++``. However different implementations of ``MPI`` may have different names for those wrappers. Spack provides an idiomatic way to use MPI compilers in your package. To use MPI wrappers to compile your whole build, do this in your ``install()`` method: .. code-block:: python env['CC'] = spec['mpi'].mpicc env['CXX'] = spec['mpi'].mpicxx env['F77'] = spec['mpi'].mpif77 env['FC'] = spec['mpi'].mpifc That's all. A longer explanation of why this works is below. We don't try to force any particular build method on packagers. The decision to use MPI wrappers depends on the way the package is written, on common practice, and on "what works". Loosely, There are three types of MPI builds: 1. Some build systems work well without the wrappers and can treat MPI as an external library, where the person doing the build has to supply includes/libs/etc. This is fairly uncommon. 2. Others really want the wrappers and assume you're using an MPI "compiler" – i.e., they have no mechanism to add MPI includes/libraries/etc. 3. CMake's ``FindMPI`` needs the compiler wrappers, but it uses them to extract ``–I`` / ``-L`` / ``-D`` arguments, then treats MPI like a regular library. Note that some CMake builds fall into case 2 because they either don't know about or don't like CMake's ``FindMPI`` support – they just assume an MPI compiler. Also, some autotools builds fall into case 3 (e.g. `here is an autotools version of CMake's FindMPI `_). Given all of this, we leave the use of the wrappers up to the packager. Spack will support all three ways of building MPI packages. ^^^^^^^^^^^^^^^^^^^^^ Packaging Conventions ^^^^^^^^^^^^^^^^^^^^^ As mentioned above, in the ``install()`` method, ``CC``, ``CXX``, ``F77``, and ``FC`` point to Spack's wrappers around the chosen compiler. Spack's wrappers are not the MPI compiler wrappers, though they do automatically add ``–I``, ``–L``, and ``–Wl,-rpath`` args for dependencies in a similar way. The MPI wrappers are a bit different in that they also add ``-l`` arguments for the MPI libraries, and some add special ``-D`` arguments to trigger build options in MPI programs. For case 1 above, you generally don't need to do more than patch your Makefile or add configure args as you normally would. For case 3, you don't need to do much of anything, as Spack puts the MPI compiler wrappers in the PATH, and the build will find them and interrogate them. For case 2, things are a bit more complicated, as you'll need to tell the build to use the MPI compiler wrappers instead of Spack's compiler wrappers. All it takes some lines like this: .. code-block:: python env['CC'] = spec['mpi'].mpicc env['CXX'] = spec['mpi'].mpicxx env['F77'] = spec['mpi'].mpif77 env['FC'] = spec['mpi'].mpifc Or, if you pass CC, CXX, etc. directly to your build with, e.g., `--with-cc=`, you'll want to substitute `spec['mpi'].mpicc` in there instead, e.g.: .. code-block:: python configure('—prefix=%s' % prefix, '—with-cc=%s' % spec['mpi'].mpicc) Now, you may think that doing this will lose the includes, library paths, and RPATHs that Spack's compiler wrapper get you, but we've actually set things up so that the MPI compiler wrappers use Spack's compiler wrappers when run from within Spack. So using the MPI wrappers should really be as simple as the code above. ^^^^^^^^^^^^^^^^^^^^^ ``spec['mpi']`` ^^^^^^^^^^^^^^^^^^^^^ Ok, so how does all this work? If your package has a virtual dependency like ``mpi``, then referring to ``spec['mpi']`` within ``install()`` will get you the concrete ``mpi`` implementation in your dependency DAG. That is a spec object just like the one passed to install, only the MPI implementations all set some additional properties on it to help you out. E.g., in mvapich2, you'll find this: .. literalinclude:: _spack_root/var/spack/repos/builtin/packages/mvapich2/package.py :pyobject: Mvapich2.setup_dependent_package That code allows the mvapich2 package to associate an ``mpicc`` property with the ``mvapich2`` node in the DAG, so that dependents can access it. ``openmpi`` and ``mpich`` do similar things. So, no matter what MPI you're using, spec['mpi'].mpicc gets you the location of the MPI compilers. This allows us to have a fairly simple polymorphic interface for information about virtual dependencies like MPI. ^^^^^^^^^^^^^^^^^^^^^ Wrapping wrappers ^^^^^^^^^^^^^^^^^^^^^ Spack likes to use its own compiler wrappers to make it easy to add ``RPATHs`` to builds, and to try hard to ensure that your builds use the right dependencies. This doesn't play nicely by default with MPI, so we have to do a couple tricks. 1. If we build MPI with Spack's wrappers, mpicc and friends will be installed with hard-coded paths to Spack's wrappers, and using them from outside of Spack will fail because they only work within Spack. To fix this, we patch mpicc and friends to use the regular compilers. Look at the filter_compilers method in mpich, openmpi, or mvapich2 for details. 2. We still want to use the Spack compiler wrappers when Spack is calling mpicc. Luckily, wrappers in all mainstream MPI implementations provide environment variables that allow us to dynamically set the compiler to be used by mpicc, mpicxx, etc. Denis pasted some code from this below – Spack's build environment sets ``MPICC``, ``MPICXX``, etc. for mpich derivatives and ``OMPI_CC``, ``OMPI_CXX``, etc. for OpenMPI. This makes the MPI compiler wrappers use the Spack compiler wrappers so that your dependencies still get proper RPATHs even if you use the MPI wrappers. ^^^^^^^^^^^^^^^^^^^^^ MPI on Cray machines ^^^^^^^^^^^^^^^^^^^^^ The Cray programming environment notably uses ITS OWN compiler wrappers, which function like MPI wrappers. On Cray systems, the ``CC``, ``cc``, and ``ftn`` wrappers ARE the MPI compiler wrappers, and it's assumed that you'll use them for all of your builds. So on Cray we don't bother with ``mpicc``, ``mpicxx``, etc, Spack MPI implementations set ``spec['mpi'].mpicc`` to point to Spack's wrappers, which wrap the Cray wrappers, which wrap the regular compilers and include MPI flags. That may seem complicated, but for packagers, that means the same code for using MPI wrappers will work, even on even on a Cray: .. code-block:: python env['CC'] = spec['mpi'].mpicc This is because on Cray, ``spec['mpi'].mpicc`` is just ``spack_cc``. .. _checking_an_installation: ------------------------ Checking an installation ------------------------ A package that *appears* to install successfully does not mean it is actually installed correctly or will continue to work indefinitely. There are a number of possible points of failure so Spack provides features for checking the software along the way. Failures can occur during and after the installation process. The build may start but the software not end up fully installed. The installed software may not work at all or as expected. The software may work after being installed but, due to changes on the system, may stop working days, weeks, or months after being installed. This section describes Spack's support for checks that can be performed during and after its installation. The former checks are referred to as ``build-time tests`` and the latter as ``stand-alone (or smoke) tests``. .. _build_time-tests: ^^^^^^^^^^^^^^^^ Build-time tests ^^^^^^^^^^^^^^^^ Spack infers the status of a build based on the contents of the install prefix. Success is assumed if anything (e.g., a file, directory) is written after ``install()`` completes. Otherwise, the build is assumed to have failed. However, the presence of install prefix contents is not a sufficient indicator of success. Consider a simple autotools build using the following commands: .. code-block:: console $ ./configure --prefix=/path/to/installation/prefix $ make $ make install Standard Autotools and CMake do not write anything to the prefix from the ``configure`` and ``make`` commands. Files are only written from the ``make install`` after the build completes. .. note:: If you want to learn more about ``Autotools`` and ``CMake`` packages in Spack, refer to :ref:`AutotoolsPackage ` and :ref:`CMakePackage `, respectively. What can you do to check that the build is progressing satisfactorily? If there are specific files and or directories expected of a successful installation, you can add basic, fast ``sanity checks``. You can also add checks to be performed after one or more installation phases. .. _sanity-checks: """""""""""""""""""" Adding sanity checks """""""""""""""""""" Unfortunately, many builds of scientific software modify the installation prefix **before** ``make install``. Builds like this can falsely report success when an error occurs before the installation is complete. Simple sanity checks can be used to identify files and or directories that are required of a successful installation. Spack checks for the presence of the files and directories after ``install()`` runs. If any of the listed files or directories are missing, then the build will fail and the install prefix will be removed. If they all exist, then Spack considers the build successful from a sanity check perspective and keeps the prefix in place. For example, the sanity checks for the ``reframe`` package below specify that eight paths must exist within the installation prefix after the ``install`` method completes. .. code-block:: python class Reframe(Package): ... # sanity check sanity_check_is_file = [join_path('bin', 'reframe')] sanity_check_is_dir = ['bin', 'config', 'docs', 'reframe', 'tutorials', 'unittests', 'cscs-checks'] Spack will then ensure the installation created the **file**: * ``self.prefix/bin/reframe`` It will also check for the existence of the following **directories**: * ``self.prefix/bin`` * ``self.prefix/config`` * ``self.prefix/docs`` * ``self.prefix/reframe`` * ``self.prefix/tutorials`` * ``self.prefix/unittests`` * ``self.prefix/cscs-checks`` .. note:: You **MUST** use ``sanity_check_is_file`` to specify required files and ``sanity_check_is_dir`` for required directories. .. _install_phase-tests: """"""""""""""""""""""""""""""" Adding installation phase tests """"""""""""""""""""""""""""""" Sometimes packages appear to build "correctly" only to have run-time behavior issues discovered at a later stage, such as after a full software stack relying on them has been built. Checks can be performed at different phases of the package installation to possibly avoid these types of problems. Some checks are built-in to different build systems, while others will need to be added to the package. Built-in installation phase tests are provided by packages inheriting from select :ref:`build systems `, where naming conventions are used to identify typical test identifiers for those systems. In general, you won't need to add anything to your package to take advantage of these tests if your software's build system complies with the convention; otherwise, you'll want or need to override the post-phase method to perform other checks. .. list-table:: Built-in installation phase tests :header-rows: 1 * - Build System Class - Post-Build Phase Method (Runs) - Post-Install Phase Method (Runs) * - :ref:`AutotoolsPackage ` - ``check`` (``make test``, ``make check``) - ``installcheck`` (``make installcheck``) * - :ref:`CachedCMakePackage ` - ``check`` (``make check``, ``make test``) - Not applicable * - :ref:`CMakePackage ` - ``check`` (``make check``, ``make test``) - Not applicable * - :ref:`MakefilePackage ` - ``check`` (``make test``, ``make check``) - ``installcheck`` (``make installcheck``) * - :ref:`MesonPackage ` - ``check`` (``make test``, ``make check``) - Not applicable * - :ref:`PerlPackage ` - ``check`` (``make test``) - Not applicable * - :ref:`PythonPackage ` - Not applicable - ``test`` (module imports) * - :ref:`QMakePackage ` - ``check`` (``make check``) - Not applicable * - :ref:`SConsPackage ` - ``build_test`` (must be overridden) - Not applicable * - :ref:`SIPPackage ` - Not applicable - ``test`` (module imports) * - :ref:`WafPackage ` - ``build_test`` (must be overridden) - ``install_test`` (must be overridden) For example, the ``Libelf`` package inherits from ``AutotoolsPackage`` and its ``Makefile`` has a standard ``check`` target. So Spack will automatically run ``make check`` after the ``build`` phase when it is installed using the ``--test`` option, such as: .. code-block:: console $ spack install --test=root libelf In addition to overriding any built-in build system installation phase tests, you can write your own install phase tests. You will need to use two decorators for each phase test method: * ``run_after`` * ``on_package_attributes`` The first decorator tells Spack when in the installation process to run your test method installation process; namely *after* the provided installation phase. The second decorator tells Spack to only run the checks when the ``--test`` option is provided on the command line. .. note:: Be sure to place the directives above your test method in the order ``run_after`` *then* ``on_package_attributes``. .. note:: You also want to be sure the package supports the phase you use in the ``run_after`` directive. For example, ``PackageBase`` only supports the ``install`` phase while the ``AutotoolsPackage`` and ``MakefilePackage`` support both ``install`` and ``build`` phases. Assuming both ``build`` and ``install`` phases are available to you, you could add additional checks to be performed after each of those phases based on the skeleton provided below. .. code-block:: python class YourMakefilePackage(MakefilePackage): ... @run_after('build') @on_package_attributes(run_tests=True) def check_build(self): # Add your custom post-build phase tests pass @run_after('install') @on_package_attributes(run_tests=True) def check_install(self): # Add your custom post-install phase tests pass .. note:: You could also schedule work to be done **before** a given phase using the ``run_before`` decorator. By way of a concrete example, the ``reframe`` package mentioned previously has a simple installation phase check that runs the installed executable. The check is implemented as follows: .. code-block:: python class Reframe(Package): ... # check if we can run reframe @run_after('install') @on_package_attributes(run_tests=True) def check_list(self): with working_dir(self.stage.source_path): reframe = Executable(join_path(self.prefix, 'bin', 'reframe')) reframe('-l') .. warning:: The API for adding tests is not yet considered stable and may change in future releases. .. _cmd-spack-test: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Stand-alone (or smoke) tests ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ While build-time tests are integrated with the installation process, stand-alone tests are independent of that process. Consequently, such tests can be performed days, even weeks, after the software is installed. Stand-alone tests are checks that should run relatively quickly -- as in on the order of at most a few minutes -- and ideally execute all aspects of the installed software, or at least key functionality. .. note:: Execution speed is important because these tests are intended to quickly assess whether the installed software works on the system. Failing stand-alone tests indicate that there is no reason to proceed with more resource-intensive tests. Passing stand-alone (or smoke) tests can lead to more thorough testing, such as extensive unit or regression tests, or tests that run at scale. Spack support for more thorough testing is a work in progress. Stand-alone tests have their own test stage directory, which can be configured. These tests can compile or build software with the compiler used to build the package. They can use files cached from the build for testing the installation. Custom files, such as source, data, or expected outputs can be added for use in these tests. """""""""""""""""""""""""""""""""""" Configuring the test stage directory """""""""""""""""""""""""""""""""""" Stand-alone tests rely on a stage directory for building, running, and tracking results. The default directory, ``~/.spack/test``, is defined in :ref:`etc/spack/defaults/config.yaml `. You can configure the location in the high-level ``config`` by adding or changing the ``test_stage`` path in the appropriate ``config.yaml`` file such that: .. code-block:: yaml config: test_stage: /path/to/stage The package can access this path **during test processing** using `self.test_suite.stage`. .. note:: The test stage path is established for the entire suite. That means it is the root directory for all specs being installed with the same `spack test run` command. Each spec gets its own stage subdirectory. """"""""""""""""""""""""" Enabling test compilation """"""""""""""""""""""""" Some stand-alone tests will require access to the compiler with which the package was built, especially for library-only packages. You must enable loading the package's compiler configuration by setting the ``test_requires_compiler`` property to ``True`` for your package. For example: .. code-block:: python class MyPackage(Package): ... test_requires_compiler = True Setting this property to ``True`` makes the compiler available in the test environment through the canonical environment variables (e.g., ``CC``, ``CXX``, ``FC``, ``F77``). .. note:: We recommend adding the property at the top of the package with the other attributes, such as ``homepage`` and ``url``. .. _cache_extra_test_sources: """"""""""""""""""""""" Adding build-time files """"""""""""""""""""""" .. note:: We highly recommend re-using build-time tests and input files for testing installed software. These files are easier to keep synchronized since they reside within the software's repository than maintaining custom install test files with the Spack package. You can use the ``cache_extra_test_sources`` method to copy directories and or files from the build stage directory to the package's installation directory. The signature for ``cache_extra_test_sources`` is: .. code-block:: python def cache_extra_test_sources(self, srcs): where ``srcs`` is a string or a list of strings corresponding to the paths for the files and or subdirectories, relative to the staged source, that are to be copied to the corresponding relative test path under the prefix. All of the contents within each subdirectory will also be copied. For example, a package method for copying everything in the ``tests`` subdirectory plus the ``foo.c`` and ``bar.c`` files from ``examples`` can be implemented as shown below. .. note:: The method name ``copy_test_sources`` here is for illustration purposes. You are free to use a name that is more suited to your package. The key to copying the files at build time for stand-alone testing is use of the ``run_after`` directive, which ensures the associated files are copied **after** the provided build stage. .. code-block:: python class MyPackage(Package): ... @run_after('install') def copy_test_sources(self): srcs = ['tests', join_path('examples', 'foo.c'), join_path('examples', 'bar.c')] self.cache_extra_test_sources(srcs) In this case, the method copies the associated files from the build stage **after** the software is installed to the package's metadata directory. The result is the directory and files will be cached in a special test subdirectory under the installation prefix. These paths are **automatically copied** to the test stage directory during stand-alone testing. The package's ``test`` method can access them using the ``self.test_suite.current_test_cache_dir`` property. In our example, the method would use the following paths to reference the copy of each entry listed in ``srcs``, respectively: * ``join_path(self.test_suite.current_test_cache_dir, 'tests')`` * ``join_path(self.test_suite.current_test_cache_dir, 'examples', 'foo.c')`` * ``join_path(self.test_suite.current_test_cache_dir, 'examples', 'bar.c')`` .. note:: Library developers will want to build the associated tests against their **installed** libraries before running them. .. note:: While source and input files are generally recommended, binaries **may** also be cached by the build process for install testing. Only you, as the package writer or maintainer, know whether these would be appropriate for ensuring the installed software continues to work as the underlying system evolves. .. _cache_custom_files: """"""""""""""""""" Adding custom files """"""""""""""""""" Some tests may require additional files not available from the build. Examples include: - test source files - test input files - test build scripts - expected test output These extra files should be added to the ``test`` subdirectory of the package in the Spack repository. Spack will **automatically copy** the contents of that directory to the test staging directory for stand-alone testing. The ``test`` method can access those files using the ``self.test_suite.current_test_data_dir`` property. .. _expected_test_output_from_file: """"""""""""""""""""""""""""""""""" Reading expected output from a file """"""""""""""""""""""""""""""""""" The helper function ``get_escaped_text_output`` is available for packages to retrieve and properly format the text from a file that contains the output that is expected when an executable is run using ``self.run_test``. The signature for ``get_escaped_text_output`` is: .. code-block:: python def get_escaped_text_output(filename): where ``filename`` is the path to the file containing the expected output. The ``filename`` for a :ref:`custom file ` can be accessed and used as illustrated by a simplified version of an ``sqlite`` package check: .. code-block:: python class Sqlite(AutotoolsPackage): ... def test(self): test_data_dir = self.test_suite.current_test_data_dir db_filename = test_data_dir.join('packages.db') .. expected = get_escaped_text_output(test_data_dir.join('dump.out')) self.run_test('sqlite3', [db_filename, '.dump'], expected, installed=True, purpose='test: checking dump output', skip_missing=False) Expected outputs do not have to be stored with the Spack package. Maintaining them with the source is actually preferable. Suppose a package's source has ``examples/foo.c`` and ``examples/foo.out`` files that are copied for stand-alone test purposes using :ref:`cache_extra_test_sources ` and the `run_test` method builds the executable ``examples/foo``. The package can retrieve the expected output from ``examples/foo.out`` using: .. code-block:: python class MyFooPackage(Package): ... def test(self): .. filename = join_path(self.test_suite.current_test_cache_dir, 'examples', 'foo.out') expected = get_escaped_text_output(filename) .. Alternatively, suppose ``MyFooPackage`` installs tests in ``share/tests`` and their outputs in ``share/tests/outputs``. The expected output for ``foo``, assuming it is still called ``foo.out``, can be retrieved as follows: .. code-block:: python class MyFooPackage(Package): ... def test(self): .. filename = join_path(self.prefix.share.tests.outputs, 'foo.out') expected = get_escaped_text_output(filename) .. """""""""""""""""""""""" Adding stand-alone tests """""""""""""""""""""""" Stand-alone tests are defined in the package's ``test`` method. The default ``test`` method is a no-op so you'll want to override it to implement the tests. .. note:: Any package method named ``test`` is automatically executed by Spack when the ``spack test run`` command is performed. For example, the ``MyPackage`` package below provides a skeleton for the test method. .. code-block:: python class MyPackage(Package): ... def test(self): # TODO: Add quick checks of the installed software pass Stand-alone tests run in an environment that provides access to the package and all of its dependencies, including ``test``-type dependencies. Standard python ``assert`` statements and other error reporting mechanisms can be used in the ``test`` method. Spack will report such errors as test failures. You can implement multiple tests (or test parts) within the ``test`` method using the ``run_test`` method. Each invocation is run separately in a manner that allows testing to continue after failures. The signature for ``run_test`` is: .. code-block:: python def run_test(self, exe, options=[], expected=[], status=0, installed=False, purpose='', skip_missing=False, work_dir=None): where each argument has the following meaning: * ``exe`` is the executable to run. If a name, the ``exe`` is required to be found in one of the paths in the ``PATH`` environment variable **unless** ``skip_missing`` is ``True``. Alternatively, a relative (to ``work_dir``) or fully qualified path for the executable can be provided in ``exe``. The test will fail if the resulting path is not within the prefix of the package being tested **unless** ``installed`` is ``False``. * ``options`` is a list of the command line options. Options are a list of strings to be passed to the executable when it runs. The default is ``[]``, which means no options are provided to the executable. * ``expected`` is an optional list of expected output strings. Spack requires every string in ``expected`` to be a regex matching part of the output from the test run (e.g., ``expected=['completed successfully', 'converged in']``). The output can also include expected failure outputs (e.g., ``expected=['failed to converge']``). The expected output can be :ref:`read from a file `. The default is ``expected=[]``, so Spack will not check the output. * ``status`` is the optional expected return code(s). A list of return codes corresponding to successful execution can be provided (e.g., ``status=[0,3,7]``). Support for non-zero return codes allows for basic **expected failure** tests as well as different return codes across versions of the software. The default is ``status=[0]``, which corresponds to **successful** execution in the sense that the executable does not exit with a failure code or raise an exception. * ``installed`` is used to require ``exe`` to be within the package prefix. If ``True``, then the path for ``exe`` is required to be within the package prefix; otherwise, the path is not constrained. The default is ``False``, so the fully qualified path for ``exe`` does **not** need to be within the installation directory. * ``purpose`` is an optional heading describing the the test part. Output from the test is written to a test log file so this argument serves as a searchable heading in text logs to highlight the start of the test part. Having a description can be helpful when debugging failing tests. * ``skip_missing`` is used to determine if the test should be skipped. If ``True``, then the test part should be skipped if the executable is missing; otherwise, the executable must exist. This option can be useful when test executables are removed or change as the software evolves in subsequent versions. The default is ``False``, which means the test executable must be present for any installable version of the software. * ``work_dir`` is the path to the directory from which the executable will run. The default of ``None`` corresponds to the current directory (``'.'``). Each call starts with the working directory set to the spec's test stage directory (i.e., ``self.test_suite.test_dir_for_spec(self.spec)``). .. warning:: Use of the package spec's installation directory for building and running tests is **strongly** discouraged. Doing so has caused permission errors for shared spack instances *and* for facilities that install the software in read-only file systems or directories. """"""""""""""""""""""""""""""""""""""""" Accessing package- and test-related files """"""""""""""""""""""""""""""""""""""""" You may need to access files from one or more locations when writing stand-alone tests. This can happen if the software's repository does not include test source files or includes files but has no way to build the executables using the installed headers and libraries. In these cases, you may need to reference the files relative to one or more root directory. The properties containing package- (or spec-) and test-related directory paths are provided in the table below. .. list-table:: Directory-to-property mapping :header-rows: 1 * - Root Directory - Package Property - Example(s) * - Package (Spec) Installation - ``self.prefix`` - ``self.prefix.include``, ``self.prefix.lib`` * - Dependency Installation - ``self.spec[''].prefix`` - ``self.spec['trilinos'].prefix.include`` * - Test Suite Stage - ``self.test_suite.stage`` - ``join_path(self.test_suite.stage, 'results.txt')`` * - Spec's Test Stage - ``self.test_suite.test_dir_for_spec`` - ``self.test_suite.test_dir_for_spec(self.spec)`` * - Current Spec's Build-time Files - ``self.test_suite.current_test_cache_dir`` - ``join_path(self.test_suite.current_test_cache_dir, 'examples', 'foo.c')`` * - Current Spec's Custom Test Files - ``self.test_suite.current_test_data_dir`` - ``join_path(self.test_suite.current_test_data_dir, 'hello.f90')`` """""""""""""""""""""""""""" Inheriting stand-alone tests """""""""""""""""""""""""""" Stand-alone tests defined in parent (.e.g., :ref:`build-systems`) and virtual (e.g., :ref:`virtual-dependencies`) packages are available to packages that inherit from or provide interfaces for those packages, respectively. The table below summarizes the tests that will be included with those provided in the package itself when executing stand-alone tests. .. list-table:: Inherited/provided stand-alone tests :header-rows: 1 * - Parent/Provider Package - Stand-alone Tests * - `C `_ - Compiles ``hello.c`` and runs it * - `Cxx `_ - Compiles and runs several ``hello`` programs * - `Fortan `_ - Compiles and runs ``hello`` programs (``F`` and ``f90``) * - `Mpi `_ - Compiles and runs ``mpi_hello`` (``c``, ``fortran``) * - `PythonPackage ` - Imports installed modules These tests are very generic so it is important that package developers and maintainers provide additional stand-alone tests customized to the package. One example of a package that adds its own stand-alone (or smoke) tests is the `Openmpi package `_. The preliminary set of tests for the package performed the following checks: - installed binaries with the ``--version`` option return the expected version; - outputs from (selected) installed binaries match expectations; - ``make all`` succeeds when building examples that were copied from the source directory during package installation; and - outputs from running the copied and built examples match expectations. Below is an example of running and viewing the stand-alone tests, where only the outputs for the first of each set are shown: .. code-block:: console $ spack test run --alias openmpi-4.0.5 openmpi@4.0.5 ==> Spack test openmpi-4.0.5 ==> Testing package openmpi-4.0.5-eygjgve $ spack test results -l openmpi-4.0.5 ==> Spack test openmpi-4.0.5 ==> Testing package openmpi-4.0.5-eygjgve ==> Results for test suite 'openmpi-4.0.5': ==> openmpi-4.0.5-eygjgve PASSED ==> Testing package openmpi-4.0.5-eygjgve ==> [2021-04-26-17:35:20.259650] test: ensuring version of mpiCC is 8.3.1 ==> [2021-04-26-17:35:20.260155] '$SPACK_ROOT/opt/spack/linux-rhel7-broadwell/gcc-8.3.1/openmpi-4.0.5-eygjgvek35awfor2qaljltjind2oa67r/bin/mpiCC' '--version' g++ (GCC) 8.3.1 20190311 (Red Hat 8.3.1-3) Copyright (C) 2018 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. PASSED ... ==> [2021-04-26-17:35:20.493921] test: checking mpirun output ==> [2021-04-26-17:35:20.494461] '$SPACK_ROOT/opt/spack/linux-rhel7-broadwell/gcc-8.3.1/openmpi-4.0.5-eygjgvek35awfor2qaljltjind2oa67r/bin/mpirun' '-n' '1' 'ls' '..' openmpi-4.0.5-eygjgve repo test_suite.lock openmpi-4.0.5-eygjgve-test-out.txt results.txt PASSED ... ==> [2021-04-26-17:35:20.630452] test: ensuring ability to build the examples ==> [2021-04-26-17:35:20.630943] '/usr/bin/make' 'all' mpicc -g hello_c.c -o hello_c mpicc -g ring_c.c -o ring_c mpicc -g connectivity_c.c -o connectivity_c mpicc -g spc_example.c -o spc_example ... PASSED ==> [2021-04-26-17:35:23.291214] test: checking hello_c example output and status (0) ==> [2021-04-26-17:35:23.291841] './hello_c' Hello, world, I am 0 of 1, (Open MPI v4.0.5, package: Open MPI dahlgren@quartz2300 Distribution, ident: 4.0.5, repo rev: v4.0.5, Aug 26, 2020, 114) PASSED ... ==> [2021-04-26-17:35:24.603152] test: ensuring copied examples cleaned up ==> [2021-04-26-17:35:24.603807] '/usr/bin/make' 'clean' rm -f hello_c hello_cxx hello_mpifh hello_usempi hello_usempif08 hello_oshmem hello_oshmemcxx hello_oshmemfh Hello.class ring_c ring_cxx ring_mpifh ring_usempi ring_usempif08 ring_oshmem ring_oshmemfh Ring.class connectivity_c oshmem_shmalloc oshmem_circular_shift oshmem_max_reduction oshmem_strided_puts oshmem_symmetric_data spc_example *~ *.o PASSED ==> [2021-04-26-17:35:24.643360] test: mpicc: expect command status in [0] ==> [2021-04-26-17:35:24.643834] '$SPACK_ROOT/opt/spack/linux-rhel7-broadwell/gcc-8.3.1/openmpi-4.0.5-eygjgvek35awfor2qaljltjind2oa67r/bin/mpicc' '-o' 'mpi_hello_c' '$HOME/.spack/test/hyzq5eqlqfog6fawlzxwg3prqy5vjhms/openmpi-4.0.5-eygjgve/data/mpi/mpi_hello.c' PASSED ==> [2021-04-26-17:35:24.776765] test: mpirun: expect command status in [0] ==> [2021-04-26-17:35:24.777194] '$SPACK_ROOT/opt/spack/linux-rhel7-broadwell/gcc-8.3.1/openmpi-4.0.5-eygjgvek35awfor2qaljltjind2oa67r/bin/mpirun' '-np' '1' 'mpi_hello_c' Hello world! From rank 0 of 1 PASSED ... .. warning:: The API for adding and running stand-alone tests is not yet considered stable and may change drastically in future releases. Packages with stand-alone tests will be refactored to match changes to the API. .. _cmd-spack-test-list: """"""""""""""""""" ``spack test list`` """"""""""""""""""" Packages available for install testing can be found using the ``spack test list`` command. The command outputs all installed packages that have defined ``test`` methods. Alternatively you can use the ``--all`` option to get a list of all packages that have defined ``test`` methods even if they are not installed. For more information, refer to `spack test list `_. .. _cmd-spack-test-run: """""""""""""""""" ``spack test run`` """""""""""""""""" Install tests can be run for one or more installed packages using the ``spack test run`` command. A ``test suite`` is created from the provided specs. If no specs are provided it will test all specs in the active environment or all specs installed in Spack if no environment is active. Test suites can be named using the ``--alias`` option. Unaliased Test suites will use the content hash of their specs as their name. Some of the more commonly used debugging options are: - ``--fail-fast`` stops testing each package after the first failure - ``--fail-first`` stops testing packages after the first failure Test output is written to a text log file by default but ``junit`` and ``cdash`` are outputs are available through the ``--log-format`` option. For more information, refer to `spack test run `_. .. _cmd-spack-test-results: """""""""""""""""""""" ``spack test results`` """""""""""""""""""""" The ``spack test results`` command shows results for all completed test suites. Providing the alias or content hash limits reporting to the corresponding test suite. The ``--logs`` option includes the output generated by the associated test(s) to facilitate debugging. The ``--failed`` option limits results shown to that of the failed tests, if any, of matching packages. For more information, refer to `spack test results `_. .. _cmd-spack-test-find: """"""""""""""""""" ``spack test find`` """"""""""""""""""" The ``spack test find`` command lists the aliases or content hashes of all test suites whose results are available. For more information, refer to `spack test find `_. .. _cmd-spack-test-remove: """"""""""""""""""""" ``spack test remove`` """"""""""""""""""""" The ``spack test remove`` command removes test suites to declutter the test results directory. You are prompted to confirm the removal of each test suite **unless** you use the ``--yes-to-all`` option. For more information, refer to `spack test remove `_. .. _file-manipulation: --------------------------- File manipulation functions --------------------------- Many builds are not perfect. If a build lacks an install target, or if it does not use systems like CMake or autotools, which have standard ways of setting compilers and options, you may need to edit files or install some files yourself to get them working with Spack. You can do this with standard Python code, and Python has rich libraries with functions for file manipulation and filtering. Spack also provides a number of convenience functions of its own to make your life even easier. These functions are described in this section. All of the functions in this section can be included by simply running: .. code-block:: python from spack import * This is already part of the boilerplate for packages created with ``spack create``. ^^^^^^^^^^^^^^^^^^^ Filtering functions ^^^^^^^^^^^^^^^^^^^ :py:func:`filter_file(regex, repl, *filenames, **kwargs) ` Works like ``sed`` but with Python regular expression syntax. Takes a regular expression, a replacement, and a set of files. ``repl`` can be a raw string or a callable function. If it is a raw string, it can contain ``\1``, ``\2``, etc. to refer to capture groups in the regular expression. If it is a callable, it is passed the Python ``MatchObject`` and should return a suitable replacement string for the particular match. Examples: #. Filtering a Makefile to force it to use Spack's compiler wrappers: .. code-block:: python filter_file(r'^\s*CC\s*=.*', 'CC = ' + spack_cc, 'Makefile') filter_file(r'^\s*CXX\s*=.*', 'CXX = ' + spack_cxx, 'Makefile') filter_file(r'^\s*F77\s*=.*', 'F77 = ' + spack_f77, 'Makefile') filter_file(r'^\s*FC\s*=.*', 'FC = ' + spack_fc, 'Makefile') #. Replacing ``#!/usr/bin/perl`` with ``#!/usr/bin/env perl`` in ``bib2xhtml``: .. code-block:: python filter_file(r'#!/usr/bin/perl', '#!/usr/bin/env perl', prefix.bin.bib2xhtml) #. Switching the compilers used by ``mpich``'s MPI wrapper scripts from ``cc``, etc. to the compilers used by the Spack build: .. code-block:: python filter_file('CC="cc"', 'CC="%s"' % self.compiler.cc, prefix.bin.mpicc) filter_file('CXX="c++"', 'CXX="%s"' % self.compiler.cxx, prefix.bin.mpicxx) :py:func:`change_sed_delimiter(old_delim, new_delim, *filenames) ` Some packages, like TAU, have a build system that can't install into directories with, e.g. '@' in the name, because they use hard-coded ``sed`` commands in their build. ``change_sed_delimiter`` finds all ``sed`` search/replace commands and change the delimiter. e.g., if the file contains commands that look like ``s///``, you can use this to change them to ``s@@@``. Example of changing ``s///`` to ``s@@@`` in TAU: .. code-block:: python change_sed_delimiter('@', ';', 'configure') change_sed_delimiter('@', ';', 'utils/FixMakefile') change_sed_delimiter('@', ';', 'utils/FixMakefile.sed.default') ^^^^^^^^^^^^^^ File functions ^^^^^^^^^^^^^^ :py:func:`ancestor(dir, n=1) ` Get the n\ :sup:`th` ancestor of the directory ``dir``. :py:func:`can_access(path) ` True if we can read and write to the file at ``path``. Same as native python ``os.access(file_name, os.R_OK|os.W_OK)``. :py:func:`install(src, dest) ` Install a file to a particular location. For example, install a header into the ``include`` directory under the install ``prefix``: .. code-block:: python install('my-header.h', prefix.include) :py:func:`join_path(*paths) ` An alias for ``os.path.join``. This joins paths using the OS path separator. :py:func:`mkdirp(*paths) ` Create each of the directories in ``paths``, creating any parent directories if they do not exist. :py:func:`working_dir(dirname, kwargs) ` This is a Python `Context Manager `_ that makes it easier to work with subdirectories in builds. You use this with the Python ``with`` statement to change into a working directory, and when the with block is done, you change back to the original directory. Think of it as a safe ``pushd`` / ``popd`` combination, where ``popd`` is guaranteed to be called at the end, even if exceptions are thrown. Example usage: #. The ``libdwarf`` build first runs ``configure`` and ``make`` in a subdirectory called ``libdwarf``. It then implements the installation code itself. This is natural with ``working_dir``: .. code-block:: python with working_dir('libdwarf'): configure("--prefix=" + prefix, "--enable-shared") make() install('libdwarf.a', prefix.lib) #. Many CMake builds require that you build "out of source", that is, in a subdirectory. You can handle creating and ``cd``'ing to the subdirectory like the LLVM package does: .. code-block:: python with working_dir('spack-build', create=True): cmake('..', '-DLLVM_REQUIRES_RTTI=1', '-DPYTHON_EXECUTABLE=/usr/bin/python', '-DPYTHON_INCLUDE_DIR=/usr/include/python2.6', '-DPYTHON_LIBRARY=/usr/lib64/libpython2.6.so', *std_cmake_args) make() make("install") The ``create=True`` keyword argument causes the command to create the directory if it does not exist. :py:func:`touch(path) ` Create an empty file at ``path``. .. _make-package-findable: ---------------------------------------------------------- Making a package discoverable with ``spack external find`` ---------------------------------------------------------- The simplest way to make a package discoverable with :ref:`spack external find ` is to: 1. Define the executables associated with the package 2. Implement a method to determine the versions of these executables ^^^^^^^^^^^^^^^^^ Minimal detection ^^^^^^^^^^^^^^^^^ The first step is fairly simple, as it requires only to specify a package level ``executables`` attribute: .. code-block:: python class Foo(Package): # Each string provided here is treated as a regular expression, and # would match for example 'foo', 'foobar', and 'bazfoo'. executables = ['foo'] This attribute must be a list of strings. Each string is a regular expression (e.g. 'gcc' would match 'gcc', 'gcc-8.3', 'my-weird-gcc', etc.) to determine a set of system executables that might be part or this package. Note that to match only executables named 'gcc' the regular expression ``'^gcc$'`` must be used. Finally to determine the version of each executable the ``determine_version`` method must be implemented: .. code-block:: python @classmethod def determine_version(cls, exe): """Return either the version of the executable passed as argument or ``None`` if the version cannot be determined. Args: exe (str): absolute path to the executable being examined """ This method receives as input the path to a single executable and must return as output its version as a string; if the user cannot determine the version or determines that the executable is not an instance of the package, they can return None and the exe will be discarded as a candidate. Implementing the two steps above is mandatory, and gives the package the basic ability to detect if a spec is present on the system at a given version. .. note:: Any executable for which the ``determine_version`` method returns ``None`` will be discarded and won't appear in later stages of the workflow described below. ^^^^^^^^^^^^^^^^^^^^^^^^ Additional functionality ^^^^^^^^^^^^^^^^^^^^^^^^ Besides the two mandatory steps described above, there are also optional methods that can be implemented to either increase the amount of details being detected or improve the robustness of the detection logic in a package. """""""""""""""""""""""""""""" Variants and custom attributes """""""""""""""""""""""""""""" The ``determine_variants`` method can be optionally implemented in a package to detect additional details of the spec: .. code-block:: python @classmethod def determine_variants(cls, exes, version_str): """Return either a variant string, a tuple of a variant string and a dictionary of extra attributes that will be recorded in packages.yaml or a list of those items. Args: exes (list of str): list of executables (absolute paths) that live in the same prefix and share the same version version_str (str): version associated with the list of executables, as detected by ``determine_version`` """ This method takes as input a list of executables that live in the same prefix and share the same version string, and returns either: 1. A variant string 2. A tuple of a variant string and a dictionary of extra attributes 3. A list of items matching either 1 or 2 (if multiple specs are detected from the set of executables) If extra attributes are returned, they will be recorded in ``packages.yaml`` and be available for later reuse. As an example, the ``gcc`` package will record by default the different compilers found and an entry in ``packages.yaml`` would look like: .. code-block:: yaml packages: gcc: externals: - spec: 'gcc@9.0.1 languages=c,c++,fortran' prefix: /usr extra_attributes: compilers: c: /usr/bin/x86_64-linux-gnu-gcc-9 c++: /usr/bin/x86_64-linux-gnu-g++-9 fortran: /usr/bin/x86_64-linux-gnu-gfortran-9 This allows us, for instance, to keep track of executables that would be named differently if built by Spack (e.g. ``x86_64-linux-gnu-gcc-9`` instead of just ``gcc``). .. TODO: we need to gather some more experience on overriding 'prefix' and other special keywords in extra attributes, but as soon as we are confident that this is the way to go we should document the process. See https://github.com/spack/spack/pull/16526#issuecomment-653783204 """"""""""""""""""""""""""" Filter matching executables """"""""""""""""""""""""""" Sometimes defining the appropriate regex for the ``executables`` attribute might prove to be difficult, especially if one has to deal with corner cases or exclude "red herrings". To help keeping the regular expressions as simple as possible, each package can optionally implement a ``filter_executables`` method: .. code-block:: python @classmethod def filter_detected_exes(cls, prefix, exes_in_prefix): """Return a filtered list of the executables in prefix""" which takes as input a prefix and a list of matching executables and returns a filtered list of said executables. Using this method has the advantage of allowing custom logic for filtering, and does not restrict the user to regular expressions only. Consider the case of detecting the GNU C++ compiler. If we try to search for executables that match ``g++``, that would have the unwanted side effect of selecting also ``clang++`` - which is a C++ compiler provided by another package - if present on the system. Trying to select executables that contain ``g++`` but not ``clang`` would be quite complicated to do using regex only. Employing the ``filter_detected_exes`` method it becomes: .. code-block:: python class Gcc(Package): executables = ['g++'] def filter_detected_exes(cls, prefix, exes_in_prefix): return [x for x in exes_in_prefix if 'clang' not in x] Another possibility that this method opens is to apply certain filtering logic when specific conditions are met (e.g. take some decisions on an OS and not on another). ^^^^^^^^^^^^^^^^^^ Validate detection ^^^^^^^^^^^^^^^^^^ To increase detection robustness, packagers may also implement a method to validate the detected Spec objects: .. code-block:: python @classmethod def validate_detected_spec(cls, spec, extra_attributes): """Validate a detected spec. Raise an exception if validation fails.""" This method receives a detected spec along with its extra attributes and can be used to check that certain conditions are met by the spec. Packagers can either use assertions or raise an ``InvalidSpecDetected`` exception when the check fails. In case the conditions are not honored the spec will be discarded and any message associated with the assertion or the exception will be logged as the reason for discarding it. As an example, a package that wants to check that the ``compilers`` attribute is in the extra attributes can implement this method like this: .. code-block:: python @classmethod def validate_detected_spec(cls, spec, extra_attributes): """Check that 'compilers' is in the extra attributes.""" msg = ('the extra attribute "compilers" must be set for ' 'the detected spec "{0}"'.format(spec)) assert 'compilers' in extra_attributes, msg or like this: .. code-block:: python @classmethod def validate_detected_spec(cls, spec, extra_attributes): """Check that 'compilers' is in the extra attributes.""" if 'compilers' not in extra_attributes: msg = ('the extra attribute "compilers" must be set for ' 'the detected spec "{0}"'.format(spec)) raise InvalidSpecDetected(msg) .. _determine_spec_details: ^^^^^^^^^^^^^^^^^^^^^^^^^ Custom detection workflow ^^^^^^^^^^^^^^^^^^^^^^^^^ In the rare case when the mechanisms described so far don't fit the detection of a package, the implementation of all the methods above can be disregarded and instead a custom ``determine_spec_details`` method can be implemented directly in the package class (note that the definition of the ``executables`` attribute is still required): .. code-block:: python @classmethod def determine_spec_details(cls, prefix, exes_in_prefix): # exes_in_prefix = a set of paths, each path is an executable # prefix = a prefix that is common to each path in exes_in_prefix # return None or [] if none of the exes represent an instance of # the package. Return one or more Specs for each instance of the # package which is thought to be installed in the provided prefix This method takes as input a set of discovered executables (which match those specified by the user) as well as a common prefix shared by all of those executables. The function must return one or more :py:class:`spack.spec.Spec` associated with the executables (it can also return ``None`` to indicate that no provided executables are associated with the package). As an example, consider a made-up package called ``foo-package`` which builds an executable called ``foo``. ``FooPackage`` would appear as follows: .. code-block:: python class FooPackage(Package): homepage = "..." url = "..." version(...) # Each string provided here is treated as a regular expression, and # would match for example 'foo', 'foobar', and 'bazfoo'. executables = ['foo'] @classmethod def determine_spec_details(cls, prefix, exes_in_prefix): candidates = list(x for x in exes_in_prefix if os.path.basename(x) == 'foo') if not candidates: return # This implementation is lazy and only checks the first candidate exe_path = candidates[0] exe = Executable(exe_path) output = exe('--version', output=str, error=str) version_str = ... # parse output for version string return Spec.from_detection( 'foo-package@{0}'.format(version_str) ) .. _package-lifecycle: ----------------------------- Style guidelines for packages ----------------------------- The following guidelines are provided, in the interests of making Spack packages work in a consistent manner: ^^^^^^^^^^^^^ Variant Names ^^^^^^^^^^^^^ Spack packages with variants similar to already-existing Spack packages should use the same name for their variants. Standard variant names are: ======= ======== ======================== Name Default Description ======= ======== ======================== shared True Build shared libraries mpi True Use MPI python False Build Python extension ======= ======== ======================== If specified in this table, the corresponding default should be used when declaring a variant. The semantics of the `shared` variant are important. When a package is built `~shared`, the package guarantees that no shared libraries are built. When a package is built `+shared`, the package guarantees that shared libraries are built, but it makes no guarantee about whether static libraries are built. ^^^^^^^^^^^^^ Version Lists ^^^^^^^^^^^^^ Spack packages should list supported versions with the newest first. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Using ``home`` vs ``prefix`` ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ``home`` and ``prefix`` are both attributes that can be queried on a package's dependencies, often when passing configure arguments pointing to the location of a dependency. The difference is that while ``prefix`` is the location on disk where a concrete package resides, ``home`` is the `logical` location that a package resides, which may be different than ``prefix`` in the case of virtual packages or other special circumstances. For most use cases inside a package, it's dependency locations can be accessed via either ``self.spec['foo'].home`` or ``self.spec['foo'].prefix``. Specific packages that should be consumed by dependents via ``.home`` instead of ``.prefix`` should be noted in their respective documentation. See :ref:`custom-attributes` for more details and an example implementing a custom ``home`` attribute. --------------------------- Packaging workflow commands --------------------------- When you are building packages, you will likely not get things completely right the first time. The ``spack install`` command performs a number of tasks before it finally installs each package. It downloads an archive, expands it in a temporary directory, and only then gives control to the package's ``install()`` method. If the build doesn't go as planned, you may want to clean up the temporary directory, or if the package isn't downloading properly, you might want to run *only* the ``fetch`` stage of the build. Spack performs best-effort installation of package dependencies by default, which means it will continue to install as many dependencies as possible after detecting failures. If you are trying to install a package with a lot of dependencies where one or more may fail to build, you might want to try the ``--fail-fast`` option to stop the installation process on the first failure. A typical package workflow might look like this: .. code-block:: console $ spack edit mypackage $ spack install --fail-fast mypackage ... build breaks! ... $ spack clean mypackage $ spack edit mypackage $ spack install --fail-fast mypackage ... repeat clean/install until install works ... Below are some commands that will allow you some finer-grained control over the install process. .. _cmd-spack-fetch: ^^^^^^^^^^^^^^^ ``spack fetch`` ^^^^^^^^^^^^^^^ The first step of ``spack install``. Takes a spec and determines the correct download URL to use for the requested package version, then downloads the archive, checks it against an MD5 checksum, and stores it in a staging directory if the check was successful. The staging directory will be located under the first writable directory in the ``build_stage`` configuration setting. When run after the archive has already been downloaded, ``spack fetch`` is idempotent and will not download the archive again. .. _cmd-spack-stage: ^^^^^^^^^^^^^^^ ``spack stage`` ^^^^^^^^^^^^^^^ The second step in ``spack install`` after ``spack fetch``. Expands the downloaded archive in its temporary directory, where it will be built by ``spack install``. Similar to ``fetch``, if the archive has already been expanded, ``stage`` is idempotent. .. _cmd-spack-patch: ^^^^^^^^^^^^^^^ ``spack patch`` ^^^^^^^^^^^^^^^ After staging, Spack applies patches to downloaded packages, if any have been specified in the package file. This command will run the install process through the fetch, stage, and patch phases. Spack keeps track of whether patches have already been applied and skips this step if they have been. If Spack discovers that patches didn't apply cleanly on some previous run, then it will restage the entire package before patching. .. _cmd-spack-restage: ^^^^^^^^^^^^^^^^^ ``spack restage`` ^^^^^^^^^^^^^^^^^ Restores the source code to pristine state, as it was before building. Does this in one of two ways: #. If the source was fetched as a tarball, deletes the entire build directory and re-expands the tarball. #. If the source was checked out from a repository, this deletes the build directory and checks it out again. .. _cmd-spack-clean: ^^^^^^^^^^^^^^^ ``spack clean`` ^^^^^^^^^^^^^^^ Cleans up Spack's temporary and cached files. This command can be used to recover disk space if temporary files from interrupted or failed installs accumulate. When called with ``--stage`` or without arguments this removes all staged files. The ``--downloads`` option removes cached :ref:`cached ` downloads. You can force the removal of all install failure tracking markers using the ``--failures`` option. Note that ``spack install`` will automatically clear relevant failure markings prior to performing the requested installation(s). Long-lived caches, like the virtual package index, are removed using the ``--misc-cache`` option. The ``--python-cache`` option removes `.pyc`, `.pyo`, and `__pycache__` folders. To remove all of the above, the command can be called with ``--all``. When called with positional arguments, this command cleans up temporary files only for a particular package. If ``fetch``, ``stage``, or ``install`` are run again after this, Spack's build process will start from scratch. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Keeping the stage directory on success ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ By default, ``spack install`` will delete the staging area once a package has been successfully built and installed. Use ``--keep-stage`` to leave the build directory intact: .. code-block:: console $ spack install --keep-stage This allows you to inspect the build directory and potentially debug the build. You can use ``clean`` later to get rid of the unwanted temporary files. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Keeping the install prefix on failure ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ By default, ``spack install`` will delete any partially constructed install prefix if anything fails during ``install()``. If you want to keep the prefix anyway (e.g. to diagnose a bug), you can use ``--keep-prefix``: .. code-block:: console $ spack install --keep-prefix Note that this may confuse Spack into thinking that the package has been installed properly, so you may need to use ``spack uninstall --force`` to get rid of the install prefix before you build again: .. code-block:: console $ spack uninstall --force --------------------- Graphing dependencies --------------------- .. _cmd-spack-graph: ^^^^^^^^^^^^^^^ ``spack graph`` ^^^^^^^^^^^^^^^ Spack provides the ``spack graph`` command for graphing dependencies. The command by default generates an ASCII rendering of a spec's dependency graph. For example: .. command-output:: spack graph hdf5 At the top is the root package in the DAG, with dependency edges emerging from it. On a color terminal, the edges are colored by which dependency they lead to. .. command-output:: spack graph --deptype=link hdf5 The ``deptype`` argument tells Spack what types of dependencies to graph. By default it includes link and run dependencies but not build dependencies. Supplying ``--deptype=link`` will show only link dependencies. The default is ``--deptype=all``, which is equivalent to ``--deptype=build,link,run,test``. Options for ``deptype`` include: * Any combination of ``build``, ``link``, ``run``, and ``test`` separated by commas. * ``all`` for all types of dependencies. You can also use ``spack graph`` to generate graphs in the widely used `Dot `_ format. For example: .. command-output:: spack graph --dot hdf5 This graph can be provided as input to other graphing tools, such as those in `Graphviz `_. If you have graphviz installed, you can write straight to PDF like this: .. code-block:: console $ spack graph --dot hdf5 | dot -Tpdf > hdf5.pdf .. _packaging-shell-support: ------------------------- Interactive shell support ------------------------- Spack provides some limited shell support to make life easier for packagers. You can enable these commands by sourcing a setup file in the ``share/spack`` directory. For ``bash`` or ``ksh``, run: .. code-block:: sh export SPACK_ROOT=/path/to/spack . $SPACK_ROOT/share/spack/setup-env.sh For ``csh`` and ``tcsh`` run: .. code-block:: csh setenv SPACK_ROOT /path/to/spack source $SPACK_ROOT/share/spack/setup-env.csh ``spack cd`` will then be available. .. _cmd-spack-cd: ^^^^^^^^^^^^ ``spack cd`` ^^^^^^^^^^^^ ``spack cd`` allows you to quickly cd to pertinent directories in Spack. Suppose you've staged a package but you want to modify it before you build it: .. code-block:: console $ spack stage libelf ==> Trying to fetch from http://www.mr511.de/software/libelf-0.8.13.tar.gz ######################################################################## 100.0% ==> Staging archive: ~/spack/var/spack/stage/libelf@0.8.13%gcc@4.8.3 arch=linux-debian7-x86_64/libelf-0.8.13.tar.gz ==> Created stage in ~/spack/var/spack/stage/libelf@0.8.13%gcc@4.8.3 arch=linux-debian7-x86_64. $ spack cd libelf $ pwd ~/spack/var/spack/stage/libelf@0.8.13%gcc@4.8.3 arch=linux-debian7-x86_64/libelf-0.8.13 ``spack cd`` here changed the current working directory to the directory containing the expanded ``libelf`` source code. There are a number of other places you can cd to in the spack directory hierarchy: .. command-output:: spack cd --help Some of these change directory into package-specific locations (stage directory, install directory, package directory) and others change to core spack locations. For example, ``spack cd --module-dir`` will take you to the main python source directory of your spack install. .. _cmd-spack-build-env: ^^^^^^^^^^^^^^^^^^^ ``spack build-env`` ^^^^^^^^^^^^^^^^^^^ ``spack build-env`` functions much like the standard unix ``build-env`` command, but it takes a spec as an argument. You can use it to see the environment variables that will be set when a particular build runs, for example: .. code-block:: console $ spack build-env mpileaks@1.1%intel This will display the entire environment that will be set when the ``mpileaks@1.1%intel`` build runs. To run commands in a package's build environment, you can simply provide them after the spec argument to ``spack build-env``: .. code-block:: console $ spack cd mpileaks@1.1%intel $ spack build-env mpileaks@1.1%intel ./configure This will cd to the build directory and then run ``configure`` in the package's build environment. .. _cmd-spack-location: ^^^^^^^^^^^^^^^^^^ ``spack location`` ^^^^^^^^^^^^^^^^^^ ``spack location`` is the same as ``spack cd`` but it does not require shell support. It simply prints out the path you ask for, rather than cd'ing to it. In bash, this: .. code-block:: console $ cd $(spack location --build-dir ) is the same as: .. code-block:: console $ spack cd --build-dir ``spack location`` is intended for use in scripts or makefiles that need to know where packages are installed. e.g., in a makefile you might write: .. code-block:: makefile DWARF_PREFIX = $(spack location --install-dir libdwarf) CXXFLAGS += -I$DWARF_PREFIX/include CXXFLAGS += -L$DWARF_PREFIX/lib .. _package_class_structure: -------------------------- Package class architecture -------------------------- .. note:: This section aims to provide a high-level knowledge of how the package class architecture evolved in Spack, and provides some insights on the current design. Packages in Spack were originally designed to support only a single build system. The overall class structure for a package looked like: .. image:: images/original_package_architecture.png :scale: 60 % :align: center In this architecture the base class ``AutotoolsPackage`` was responsible for both the metadata related to the ``autotools`` build system (e.g. dependencies or variants common to all packages using it), and for encoding the default installation procedure. In reality, a non-negligible number of packages are either changing their build system during the evolution of the project, or using different build systems for different platforms. An architecture based on a single class requires hacks or other workarounds to deal with these cases. To support a model more adherent to reality, Spack v0.19 changed its internal design by extracting the attributes and methods related to building a software into a separate hierarchy: .. image:: images/builder_package_architecture.png :scale: 60 % :align: center In this new format each ``package.py`` contains one ``*Package`` class that gathers all the metadata, and one or more ``*Builder`` classes that encode the installation procedure. A specific builder object is created just before the software is built, so at a time where Spack knows which build system needs to be used for the current installation, and receives a ``package`` object during initialization. ^^^^^^^^^^^^^^^^^^^^^^^^ ``build_system`` variant ^^^^^^^^^^^^^^^^^^^^^^^^ To allow imposing conditions based on the build system, each package must a have ``build_system`` variant, which is usually inherited from base classes. This variant allows for writing metadata that is conditional on the build system: .. code-block:: python with when("build_system=cmake"): depends_on("cmake", type="build") and also for selecting a specific build system from a spec literal, like in the following command: .. code-block:: console $ spack install arpack-ng build_system=autotools ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Compatibility with single-class format ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Internally, Spack always uses builders to perform operations related to the installation of a specific software. The builders are created in the ``spack.builder.create`` function .. literalinclude:: _spack_root/lib/spack/spack/builder.py :pyobject: create To achieve backward compatibility with the single-class format Spack creates in this function a special "adapter builder", if no custom builder is detected in the recipe: .. image:: images/adapter.png :scale: 60 % :align: center Overall the role of the adapter is to route access to attributes of methods first through the ``*Package`` hierarchy, and then back to the base class builder. This is schematically shown in the diagram above, where the adapter role is to "emulate" a method resolution order like the one represented by the red arrows.