.. 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) .. _environments: ========================= Environments (spack.yaml) ========================= An environment is used to group together a set of specs for the purpose of building, rebuilding and deploying in a coherent fashion. Environments provide a number of advantages over the *à la carte* approach of building and loading individual Spack modules: #. Environments separate the steps of (a) choosing what to install, (b) concretizing, and (c) installing. This allows Environments to remain stable and repeatable, even if Spack packages are upgraded: specs are only re-concretized when the user explicitly asks for it. It is even possible to reliably transport environments between different computers running different versions of Spack! #. Environments allow several specs to be built at once; a more robust solution than ad-hoc scripts making multiple calls to ``spack install``. #. An Environment that is built as a whole can be loaded as a whole into the user environment. An Environment can be built to maintain a filesystem view of its packages, and the environment can load that view into the user environment at activation time. Spack can also generate a script to load all modules related to an environment. Other packaging systems also provide environments that are similar in some ways to Spack environments; for example, `Conda environments `_ or `Python Virtual Environments `_. Spack environments provide some distinctive features: #. A spec installed "in" an environment is no different from the same spec installed anywhere else in Spack. Environments are assembled simply by collecting together a set of specs. #. Spack Environments may contain more than one spec of the same package. Spack uses a "manifest and lock" model similar to `Bundler gemfiles `_ and other package managers. The user input file is named ``spack.yaml`` and the lock file is named ``spack.lock`` .. _environments-using: ------------------ Using Environments ------------------ Here we follow a typical use case of creating, concretizing, installing and loading an environment. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Creating a named Environment ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ An environment is created by: .. code-block:: console $ spack env create myenv Spack then creates the directory ``var/spack/environments/myenv``. .. note:: All named environments are stored in the ``var/spack/environments`` folder. In the ``var/spack/environments/myenv`` directory, Spack creates the file ``spack.yaml`` and the hidden directory ``.spack-env``. Spack stores metadata in the ``.spack-env`` directory. User interaction will occur through the ``spack.yaml`` file and the Spack commands that affect it. When the environment is concretized, Spack will create a file ``spack.lock`` with the concrete information for the environment. In addition to being the default location for the view associated with an Environment, the ``.spack-env`` directory also contains: * ``repo/``: A repo consisting of the Spack packages used in this environment. This allows the environment to build the same, in theory, even on different versions of Spack with different packages! * ``logs/``: A directory containing the build logs for the packages in this Environment. Spack Environments can also be created from either a ``spack.yaml`` manifest or a ``spack.lock`` lockfile. To create an Environment from a ``spack.yaml`` manifest: .. code-block:: console $ spack env create myenv spack.yaml To create an Environment from a ``spack.lock`` lockfile: .. code-block:: console $ spack env create myenv spack.lock Either of these commands can also take a full path to the initialization file. A Spack Environment created from a ``spack.yaml`` manifest is guaranteed to have the same root specs as the original Environment, but may concretize differently. A Spack Environment created from a ``spack.lock`` lockfile is guaranteed to have the same concrete specs as the original Environment. Either may obviously then differ as the user modifies it. ^^^^^^^^^^^^^^^^^^^^^^^^^ Activating an Environment ^^^^^^^^^^^^^^^^^^^^^^^^^ To activate an environment, use the following command: .. code-block:: console $ spack env activate myenv By default, the ``spack env activate`` will load the view associated with the Environment into the user environment. The ``-v, --with-view`` argument ensures this behavior, and the ``-V, --without-view`` argument activates the environment without changing the user environment variables. The ``-p`` option to the ``spack env activate`` command modifies the user's prompt to begin with the environment name in brackets. .. code-block:: console $ spack env activate -p myenv [myenv] $ ... To deactivate an environment, use the command: .. code-block:: console $ spack env deactivate or the shortcut alias .. code-block:: console $ despacktivate If the environment was activated with its view, deactivating the environment will remove the view from the user environment. ^^^^^^^^^^^^^^^^^^^^^^ Anonymous Environments ^^^^^^^^^^^^^^^^^^^^^^ Any directory can be treated as an environment if it contains a file ``spack.yaml``. To load an anonymous environment, use: .. code-block:: console $ spack env activate -d /path/to/directory Anonymous specs can be created in place using the command: .. code-block:: console $ spack env create -d . In this case Spack simply creates a spack.yaml file in the requested directory. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Environment Sensitive Commands ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Spack commands are environment sensitive. For example, the ``find`` command shows only the specs in the active Environment if an Environment has been activated. Similarly, the ``install`` and ``uninstall`` commands act on the active environment. .. code-block:: console $ spack find ==> 0 installed packages $ spack install zlib@1.2.11 ==> Installing zlib-1.2.11-q6cqrdto4iktfg6qyqcc5u4vmfmwb7iv ==> No binary for zlib-1.2.11-q6cqrdto4iktfg6qyqcc5u4vmfmwb7iv found: installing from source ==> zlib: Executing phase: 'install' [+] ~/spack/opt/spack/linux-rhel7-broadwell/gcc-8.1.0/zlib-1.2.11-q6cqrdto4iktfg6qyqcc5u4vmfmwb7iv $ spack env activate myenv $ spack find ==> In environment myenv ==> No root specs ==> 0 installed packages $ spack install zlib@1.2.8 ==> Installing zlib-1.2.8-yfc7epf57nsfn2gn4notccaiyxha6z7x ==> No binary for zlib-1.2.8-yfc7epf57nsfn2gn4notccaiyxha6z7x found: installing from source ==> zlib: Executing phase: 'install' [+] ~/spack/opt/spack/linux-rhel7-broadwell/gcc-8.1.0/zlib-1.2.8-yfc7epf57nsfn2gn4notccaiyxha6z7x ==> Updating view at ~/spack/var/spack/environments/myenv/.spack-env/view $ spack find ==> In environment myenv ==> Root specs zlib@1.2.8 ==> 1 installed package -- linux-rhel7-broadwell / gcc@8.1.0 ---------------------------- zlib@1.2.8 $ despacktivate $ spack find ==> 2 installed packages -- linux-rhel7-broadwell / gcc@8.1.0 ---------------------------- zlib@1.2.8 zlib@1.2.11 Note that when we installed the abstract spec ``zlib@1.2.8``, it was presented as a root of the Environment. All explicitly installed packages will be listed as roots of the Environment. All of the Spack commands that act on the list of installed specs are Environment-sensitive in this way, including ``install``, ``uninstall``, ``activate``, ``deactivate``, ``find``, ``extensions``, and more. In the :ref:`environment-configuration` section we will discuss Environment-sensitive commands further. ^^^^^^^^^^^^^^^^^^^^^ Adding Abstract Specs ^^^^^^^^^^^^^^^^^^^^^ An abstract spec is the user-specified spec before Spack has applied any defaults or dependency information. Users can add abstract specs to an Environment using the ``spack add`` command. The most important component of an Environment is a list of abstract specs. Adding a spec adds to the manifest (the ``spack.yaml`` file), which is used to define the roots of the Environment, but does not affect the concrete specs in the lockfile, nor does it install the spec. The ``spack add`` command is environment aware. It adds to the currently active environment. All environment aware commands can also be called using the ``spack -e`` flag to specify the environment. .. code-block:: console $ spack env activate myenv $ spack add mpileaks or .. code-block:: console $ spack -e myenv add python .. _environments_concretization: ^^^^^^^^^^^^ Concretizing ^^^^^^^^^^^^ Once some user specs have been added to an environment, they can be concretized. There are at the moment three different modes of operation to concretize an environment, which are explained in details in :ref:`environments_concretization_config`. Regardless of which mode of operation has been chosen, the following command will ensure all the root specs are concretized according to the constraints that are prescribed in the configuration: .. code-block:: console [myenv]$ spack concretize In the case of specs that are not concretized together, the command above will concretize only the specs that were added and not yet concretized. Forcing a re-concretization of all the specs can be done instead with this command: .. code-block:: console [myenv]$ spack concretize -f When the ``-f`` flag is not used to reconcretize all specs, Spack guarantees that already concretized specs are unchanged in the environment. The ``concretize`` command does not install any packages. For packages that have already been installed outside of the environment, the process of adding the spec and concretizing is identical to installing the spec assuming it concretizes to the exact spec that was installed outside of the environment. The ``spack find`` command can show concretized specs separately from installed specs using the ``-c`` (``--concretized``) flag. .. code-block:: console [myenv]$ spack add zlib [myenv]$ spack concretize [myenv]$ spack find -c ==> In environment myenv ==> Root specs zlib ==> Concretized roots -- linux-rhel7-x86_64 / gcc@4.9.3 ------------------------------- zlib@1.2.11 ==> 0 installed packages .. _installing-environment: ^^^^^^^^^^^^^^^^^^^^^^^^^ Installing an Environment ^^^^^^^^^^^^^^^^^^^^^^^^^ In addition to installing individual specs into an Environment, one can install the entire Environment at once using the command .. code-block:: console [myenv]$ spack install If the Environment has been concretized, Spack will install the concretized specs. Otherwise, ``spack install`` will first concretize the Environment and then install the concretized specs. .. note:: Every ``spack install`` process builds one package at a time with multiple build jobs, controlled by the ``-j`` flag and the ``config:build_jobs`` option (see :ref:`build-jobs`). To speed up environment builds further, independent packages can be installed in parallel by launching more Spack instances. For example, the following will build at most four packages in parallel using three background jobs: .. code-block:: console [myenv]$ spack install & spack install & spack install & spack install Another option is to generate a ``Makefile`` and run ``make -j`` to control the number of parallel install processes. See :ref:`env-generate-depfile` for details. As it installs, ``spack install`` creates symbolic links in the ``logs/`` directory in the Environment, allowing for easy inspection of build logs related to that environment. The ``spack install`` command also stores a Spack repo containing the ``package.py`` file used at install time for each package in the ``repos/`` directory in the Environment. The ``--no-add`` option can be used in a concrete environment to tell spack to install specs already present in the environment but not to add any new root specs to the environment. For root specs provided to ``spack install`` on the command line, ``--no-add`` is the default, while for dependency specs on the other hand, it is optional. In other words, if there is an unambiguous match in the active concrete environment for a root spec provided to ``spack install`` on the command line, spack does not require you to specify the ``--no-add`` option to prevent the spec from being added again. At the same time, a spec that already exists in the environment, but only as a dependency, will be added to the environment as a root spec without the ``--no-add`` option. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Developing Packages in a Spack Environment ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The ``spack develop`` command allows one to develop Spack packages in an environment. It requires a spec containing a concrete version, and will configure Spack to install the package from local source. By default, it will also clone the package to a subdirectory in the environment. This package will have a special variant ``dev_path`` set, and Spack will ensure the package and its dependents are rebuilt any time the environment is installed if the package's local source code has been modified. Spack ensures that all instances of a developed package in the environment are concretized to match the version (and other constraints) passed as the spec argument to the ``spack develop`` command. For packages with ``git`` attributes, git branches, tags, and commits can also be used as valid concrete versions (see :ref:`version-specifier`). This means that for a package ``foo``, ``spack develop foo@git.main`` will clone the ``main`` branch of the package, and ``spack install`` will install from that git clone if ``foo`` is in the environment. Further development on ``foo`` can be tested by reinstalling the environment, and eventually committed and pushed to the upstream git repo. ^^^^^^^ Loading ^^^^^^^ Once an environment has been installed, the following creates a load script for it: .. code-block:: console $ spack env loads -r This creates a file called ``loads`` in the environment directory. Sourcing that file in Bash will make the environment available to the user; and can be included in ``.bashrc`` files, etc. The ``loads`` file may also be copied out of the environment, renamed, etc. .. _environment-configuration: ------------------------ Configuring Environments ------------------------ A variety of Spack behaviors are changed through Spack configuration files, covered in more detail in the :ref:`configuration` section. Spack Environments provide an additional level of configuration scope between the custom scope and the user scope discussed in the configuration documentation. There are two ways to include configuration information in a Spack Environment: #. Inline in the ``spack.yaml`` file #. Included in the ``spack.yaml`` file from another file. Many Spack commands also affect configuration information in files automatically. Those commands take a ``--scope`` argument, and the environment can be specified by ``env:NAME`` (to affect environment ``foo``, set ``--scope env:foo``). These commands will automatically manipulate configuration inline in the ``spack.yaml`` file. ^^^^^^^^^^^^^^^^^^^^^ Inline configurations ^^^^^^^^^^^^^^^^^^^^^ Inline Environment-scope configuration is done using the same yaml format as standard Spack configuration scopes, covered in the :ref:`configuration` section. Each section is contained under a top-level yaml object with it's name. For example, a ``spack.yaml`` manifest file containing some package preference configuration (as in a ``packages.yaml`` file) could contain: .. code-block:: yaml spack: ... packages: all: compiler: [intel] ... This configuration sets the default compiler for all packages to ``intel``. ^^^^^^^^^^^^^^^^^^^^^^^ Included configurations ^^^^^^^^^^^^^^^^^^^^^^^ Spack environments allow an ``include`` heading in their yaml schema. This heading pulls in external configuration files and applies them to the Environment. .. code-block:: yaml spack: include: - relative/path/to/config.yaml - https://github.com/path/to/raw/config/compilers.yaml - /absolute/path/to/packages.yaml Environments can include files or URLs. File paths can be relative or absolute. URLs include the path to the text for individual files or can be the path to a directory containing configuration files. ^^^^^^^^^^^^^^^^^^^^^^^^ Configuration precedence ^^^^^^^^^^^^^^^^^^^^^^^^ Inline configurations take precedence over included configurations, so you don't have to change shared configuration files to make small changes to an individual environment. Included configurations listed earlier will have higher precedence, as the included configs are applied in reverse order. ------------------------------- Manually Editing the Specs List ------------------------------- The list of abstract/root specs in the Environment is maintained in the ``spack.yaml`` manifest under the heading ``specs``. .. code-block:: yaml spack: specs: - ncview - netcdf - nco - py-sphinx Appending to this list in the yaml is identical to using the ``spack add`` command from the command line. However, there is more power available from the yaml file. .. _environments_concretization_config: ^^^^^^^^^^^^^^^^^^^ Spec concretization ^^^^^^^^^^^^^^^^^^^ An environment can be concretized in three different modes and the behavior active under any environment is determined by the ``concretizer:unify`` property. By default specs are concretized *separately*, one after the other: .. code-block:: yaml spack: specs: - hdf5~mpi - hdf5+mpi - zlib@1.2.8 concretizer: unify: false This mode of operation permits to deploy a full software stack where multiple configurations of the same package need to be installed alongside each other using the best possible selection of transitive dependencies. The downside is that redundancy of installations is disregarded completely, and thus environments might be more bloated than strictly needed. In the example above, for instance, if a version of ``zlib`` newer than ``1.2.8`` is known to Spack, then it will be used for both ``hdf5`` installations. If redundancy of the environment is a concern, Spack provides a way to install it *together where possible*, i.e. trying to maximize reuse of dependencies across different specs: .. code-block:: yaml spack: specs: - hdf5~mpi - hdf5+mpi - zlib@1.2.8 concretizer: unify: when_possible Also in this case Spack allows having multiple configurations of the same package, but privileges the reuse of specs over other factors. Going back to our example, this means that both ``hdf5`` installations will use ``zlib@1.2.8`` as a dependency even if newer versions of that library are available. Central installations done at HPC centers by system administrators or user support groups are a common case that fits either of these two modes. Environments can also be configured to concretize all the root specs *together*, in a self-consistent way, to ensure that each package in the environment comes with a single configuration: .. code-block:: yaml spack: specs: - hdf5+mpi - zlib@1.2.8 concretizer: unify: true This mode of operation is usually what is required by software developers that want to deploy their development environment and have a single view of it in the filesystem. .. note:: The ``concretizer:unify`` config option was introduced in Spack 0.18 to replace the ``concretization`` property. For reference, ``concretization: together`` is replaced by ``concretizer:unify:true``, and ``concretization: separately`` is replaced by ``concretizer:unify:false``. .. admonition:: Re-concretization of user specs When concretizing specs *together* or *together where possible* the entire set of specs will be re-concretized after any addition of new user specs, to ensure that the environment remains consistent / minimal. When instead the specs are concretized separately only the new specs will be re-concretized after any addition. ^^^^^^^^^^^^^ Spec Matrices ^^^^^^^^^^^^^ Entries in the ``specs`` list can be individual abstract specs or a spec matrix. A spec matrix is a yaml object containing multiple lists of specs, and evaluates to the cross-product of those specs. Spec matrices also contain an ``excludes`` directive, which eliminates certain combinations from the evaluated result. The following two Environment manifests are identical: .. code-block:: yaml spack: specs: - zlib %gcc@7.1.0 - zlib %gcc@4.9.3 - libelf %gcc@7.1.0 - libelf %gcc@4.9.3 - libdwarf %gcc@7.1.0 - cmake spack: specs: - matrix: - [zlib, libelf, libdwarf] - ['%gcc@7.1.0', '%gcc@4.9.3'] exclude: - libdwarf%gcc@4.9.3 - cmake Spec matrices can be used to install swaths of software across various toolchains. The concretization logic for spec matrices differs slightly from the rest of Spack. If a variant or dependency constraint from a matrix is invalid, Spack will reject the constraint and try again without it. For example, the following two Environment manifests will produce the same specs: .. code-block:: yaml spack: specs: - matrix: - [zlib, libelf, hdf5+mpi] - [^mvapich2@2.2, ^openmpi@3.1.0] spack: specs: - zlib - libelf - hdf5+mpi ^mvapich2@2.2 - hdf5+mpi ^openmpi@3.1.0 This allows one to create toolchains out of combinations of constraints and apply them somewhat indiscriminately to packages, without regard for the applicability of the constraint. ^^^^^^^^^^^^^^^^^^^^ Spec List References ^^^^^^^^^^^^^^^^^^^^ The last type of possible entry in the specs list is a reference. The Spack Environment manifest yaml schema contains an additional heading ``definitions``. Under definitions is an array of yaml objects. Each object has one or two fields. The one required field is a name, and the optional field is a ``when`` clause. The named field is a spec list. The spec list uses the same syntax as the ``specs`` entry. Each entry in the spec list can be a spec, a spec matrix, or a reference to an earlier named list. References are specified using the ``$`` sigil, and are "splatted" into place (i.e. the elements of the referent are at the same level as the elements listed separately). As an example, the following two manifest files are identical. .. code-block:: yaml spack: definitions: - first: [libelf, libdwarf] - compilers: ['%gcc', '%intel'] - second: - $first - matrix: - [zlib] - [$compilers] specs: - $second - cmake spack: specs: - libelf - libdwarf - zlib%gcc - zlib%intel - cmake .. note:: Named spec lists in the definitions section may only refer to a named list defined above itself. Order matters. In short files like the example, it may be easier to simply list the included specs. However for more complicated examples involving many packages across many toolchains, separately factored lists make Environments substantially more manageable. Additionally, the ``-l`` option to the ``spack add`` command allows one to add to named lists in the definitions section of the manifest file directly from the command line. The ``when`` directive can be used to conditionally add specs to a named list. The ``when`` directive takes a string of Python code referring to a restricted set of variables, and evaluates to a boolean. The specs listed are appended to the named list if the ``when`` string evaluates to ``True``. In the following snippet, the named list ``compilers`` is ``['%gcc', '%clang', '%intel']`` on ``x86_64`` systems and ``['%gcc', '%clang']`` on all other systems. .. code-block:: yaml spack: definitions: - compilers: ['%gcc', '%clang'] - when: arch.satisfies('x86_64:') compilers: ['%intel'] .. note:: Any definitions with the same named list with true ``when`` clauses (or absent ``when`` clauses) will be appended together The valid variables for a ``when`` clause are: #. ``platform``. The platform string of the default Spack architecture on the system. #. ``os``. The os string of the default Spack architecture on the system. #. ``target``. The target string of the default Spack architecture on the system. #. ``architecture`` or ``arch``. A Spack spec satisfying the default Spack architecture on the system. This supports querying via the ``satisfies`` method, as shown above. #. ``arch_str``. The architecture string of the default Spack architecture on the system. #. ``re``. The standard regex module in Python. #. ``env``. The user environment (usually ``os.environ`` in Python). #. ``hostname``. The hostname of the system (if ``hostname`` is an executable in the user's PATH). ^^^^^^^^^^^^^^^^^^^^^^^^ SpecLists as Constraints ^^^^^^^^^^^^^^^^^^^^^^^^ Dependencies and compilers in Spack can be both packages in an environment and constraints on other packages. References to SpecLists allow a shorthand to treat packages in a list as either a compiler or a dependency using the ``$%`` or ``$^`` syntax respectively. For example, the following environment has three root packages: ``gcc@8.1.0``, ``mvapich2@2.3.1 %gcc@8.1.0``, and ``hdf5+mpi %gcc@8.1.0 ^mvapich2@2.3.1``. .. code-block:: yaml spack: definitions: - compilers: [gcc@8.1.0] - mpis: [mvapich2@2.3.1] - packages: [hdf5+mpi] specs: - $compilers - matrix: - [$mpis] - [$%compilers] - matrix: - [$packages] - [$^mpis] - [$%compilers] This allows for a much-needed reduction in redundancy between packages and constraints. ---------------- Filesystem Views ---------------- Spack Environments can define filesystem views, which provide a direct access point for software similar to the directory hierarchy that might exist under ``/usr/local``. Filesystem views are updated every time the environment is written out to the lock file ``spack.lock``, so the concrete environment and the view are always compatible. The files of the view's installed packages are brought into the view by symbolic or hard links, referencing the original Spack installation, or by copy. .. _configuring_environment_views: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Configuration in ``spack.yaml`` ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The Spack Environment manifest file has a top-level keyword ``view``. Each entry under that heading is a **view descriptor**, headed by a name. Any number of views may be defined under the ``view`` heading. The view descriptor contains the root of the view, and optionally the projections for the view, ``select`` and ``exclude`` lists for the view and link information via ``link`` and ``link_type``. For example, in the following manifest file snippet we define a view named ``mpis``, rooted at ``/path/to/view`` in which all projections use the package name, version, and compiler name to determine the path for a given package. This view selects all packages that depend on MPI, and excludes those built with the PGI compiler at version 18.5. The root specs with their (transitive) link and run type dependencies will be put in the view due to the ``link: all`` option, and the files in the view will be symlinks to the spack install directories. .. code-block:: yaml spack: ... view: mpis: root: /path/to/view select: [^mpi] exclude: ['%pgi@18.5'] projections: all: '{name}/{version}-{compiler.name}' link: all link_type: symlink The default for the ``select`` and ``exclude`` values is to select everything and exclude nothing. The default projection is the default view projection (``{}``). The ``link`` attribute allows the following values: #. ``link: all`` include root specs with their transitive run and link type dependencies (default); #. ``link: run`` include root specs with their transitive run type dependencies; #. ``link: roots`` include root specs without their dependencies. The ``link_type`` defaults to ``symlink`` but can also take the value of ``hardlink`` or ``copy``. .. tip:: The option ``link: run`` can be used to create small environment views for Python packages. Python will be able to import packages *inside* of the view even when the environment is not activated, and linked libraries will be located *outside* of the view thanks to rpaths. There are two shorthands for environments with a single view. If the environment at ``/path/to/env`` has a single view, with a root at ``/path/to/env/.spack-env/view``, with default selection and exclusion and the default projection, we can put ``view: True`` in the environment manifest. Similarly, if the environment has a view with a different root, but default selection, exclusion, and projections, the manifest can say ``view: /path/to/view``. These views are automatically named ``default``, so that .. code-block:: yaml spack: ... view: True is equivalent to .. code-block:: yaml spack: ... view: default: root: .spack-env/view and .. code-block:: yaml spack: ... view: /path/to/view is equivalent to .. code-block:: yaml spack: ... view: default: root: /path/to/view By default, Spack environments are configured with ``view: True`` in the manifest. Environments can be configured without views using ``view: False``. For backwards compatibility reasons, environments with no ``view`` key are treated the same as ``view: True``. From the command line, the ``spack env create`` command takes an argument ``--with-view [PATH]`` that sets the path for a single, default view. If no path is specified, the default path is used (``view: True``). The argument ``--without-view`` can be used to create an environment without any view configured. The ``spack env view`` command can be used to change the manage views of an Environment. The subcommand ``spack env view enable`` will add a view named ``default`` to an environment. It takes an optional argument to specify the path for the new default view. The subcommand ``spack env view disable`` will remove the view named ``default`` from an environment if one exists. The subcommand ``spack env view regenerate`` will regenerate the views for the environment. This will apply any updates in the environment configuration that have not yet been applied. .. _view_projections: """""""""""""""" View Projections """""""""""""""" The default projection into a view is to link every package into the root of the view. The projections attribute is a mapping of partial specs to spec format strings, defined by the :meth:`~spack.spec.Spec.format` function, as shown in the example below: .. code-block:: yaml projections: zlib: {name}-{version} ^mpi: {name}-{version}/{^mpi.name}-{^mpi.version}-{compiler.name}-{compiler.version} all: {name}-{version}/{compiler.name}-{compiler.version} The entries in the projections configuration file must all be either specs or the keyword ``all``. For each spec, the projection used will be the first non-``all`` entry that the spec satisfies, or ``all`` if there is an entry for ``all`` and no other entry is satisfied by the spec. Where the keyword ``all`` appears in the file does not matter. Given the example above, the spec ``zlib@1.2.8`` will be linked into ``/my/view/zlib-1.2.8/``, the spec ``hdf5@1.8.10+mpi %gcc@4.9.3 ^mvapich2@2.2`` will be linked into ``/my/view/hdf5-1.8.10/mvapich2-2.2-gcc-4.9.3``, and the spec ``hdf5@1.8.10~mpi %gcc@4.9.3`` will be linked into ``/my/view/hdf5-1.8.10/gcc-4.9.3``. If the keyword ``all`` does not appear in the projections configuration file, any spec that does not satisfy any entry in the file will be linked into the root of the view as in a single-prefix view. Any entries that appear below the keyword ``all`` in the projections configuration file will not be used, as all specs will use the projection under ``all`` before reaching those entries. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Activating environment views ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The ``spack env activate`` command will put the default view for the environment into the user's path, in addition to activating the environment for Spack commands. The arguments ``-v,--with-view`` and ``-V,--without-view`` can be used to tune this behavior. The default behavior is to activate with the environment view if there is one. The environment variables affected by the ``spack env activate`` command and the paths that are used to update them are determined by the :ref:`prefix inspections ` defined in your modules configuration; the defaults are summarized in the following table. =================== ========= Variable Paths =================== ========= PATH bin MANPATH man, share/man ACLOCAL_PATH share/aclocal PKG_CONFIG_PATH lib/pkgconfig, lib64/pkgconfig, share/pkgconfig CMAKE_PREFIX_PATH . =================== ========= Each of these paths are appended to the view root, and added to the relevant variable if the path exists. For this reason, it is not recommended to use non-default projections with the default view of an environment. The ``spack env deactivate`` command will remove the default view of the environment from the user's path. .. _env-generate-depfile: ------------------------------------------ Generating Depfiles from Environments ------------------------------------------ Spack can generate ``Makefile``\s to make it easier to build multiple packages in an environment in parallel. Generated ``Makefile``\s expose targets that can be included in existing ``Makefile``\s, to allow other targets to depend on the environment installation. A typical workflow is as follows: .. code:: console spack env create -d . spack -e . add perl spack -e . concretize spack -e . env depfile > Makefile make -j64 This generates a ``Makefile`` from a concretized environment in the current working directory, and ``make -j64`` installs the environment, exploiting parallelism across packages as much as possible. Spack respects the Make jobserver and forwards it to the build environment of packages, meaning that a single ``-j`` flag is enough to control the load, even when packages are built in parallel. By default the following phony convenience targets are available: - ``make all``: installs the environment (default target); - ``make fetch-all``: only fetch sources of all packages; - ``make clean``: cleans files used by make, but does not uninstall packages. .. tip:: GNU Make version 4.3 and above have great support for output synchronization through the ``-O`` and ``--output-sync`` flags, which ensure that output is printed orderly per package install. To get synchronized output with colors, use ``make -j SPACK_COLOR=always --output-sync=recurse``. The following advanced example shows how generated targets can be used in a ``Makefile``: .. code:: Makefile SPACK ?= spack .PHONY: all clean env all: env spack.lock: spack.yaml $(SPACK) -e . concretize -f env.mk: spack.lock $(SPACK) -e . env depfile -o $@ --make-target-prefix spack env: spack/env $(info Environment installed!) clean: rm -rf spack.lock env.mk spack/ ifeq (,$(filter clean,$(MAKECMDGOALS))) include env.mk endif When ``make`` is invoked, it first "remakes" the missing include ``env.mk`` from its rule, which triggers concretization. When done, the generated target ``spack/env`` is available. In the above example, the ``env`` target uses this generated target as a prerequisite, meaning that it can make use of the installed packages in its commands. As it is typically undesirable to remake ``env.mk`` as part of ``make clean``, the include is conditional. .. note:: When including generated ``Makefile``\s, it is important to use the ``--make-target-prefix`` flag and use the non-phony target ``/env`` as prerequisite, instead of the phony target ``/all``.