Use code from the `distro` package to improve linux distro detection. (#1629)

* Use code from the `distro` package to improve linux distro detection.

Various issues [1] [2] with the platform.linux_distribution function led
to the function being deprecated in python 3.4. The pipi package distro
[3] contains compatible improved code that better tracks current methods
for identifying linux distributions (see, for example, [4],[5]).

[1]: https://bugs.python.org/issue20454
[2]: http://bugs.python.org/issue1322
[3]: https://pypi.python.org/pypi/distro
[4]: https://refspecs.linuxbase.org/LSB_3.0.0/LSB-PDA/LSB-PDA/lsbrelease.html
[5]: https://www.freedesktop.org/software/systemd/man/os-release.html

* fix (potential) unicode problems

2 files changed, 1051 insertions, 2 deletions

diff --git a/lib/spack/external/distro.py b/lib/spack/external/distro.py
new file mode 100644
index 0000000000..0fa183ec22
--- /dev/null
+++ b/lib/spack/external/distro.py
@@ -0,0 +1,1048 @@
+# Copyright 2015,2016 Nir Cohen
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+The ``distro`` package (``distro`` stands for Linux Distribution) provides
+information about the Linux distribution it runs on, such as a reliable
+machine-readable distro ID, or version information.
+
+It is a renewed alternative implementation for Python's original
+:py:func:`platform.linux_distribution` function, but it provides much more
+functionality. An alternative implementation became necessary because Python
+3.5 deprecated this function, and Python 3.7 is expected to remove it
+altogether. Its predecessor function :py:func:`platform.dist` was already
+deprecated since Python 2.6 and is also expected to be removed in Python 3.7.
+Still, there are many cases in which access to Linux distribution information
+is needed. See `Python issue 1322 <https://bugs.python.org/issue1322>`_ for
+more information.
+"""
+
+import os
+import re
+import sys
+import shlex
+import subprocess
+
+
+if not sys.platform.startswith('linux'):
+    raise ImportError('Unsupported platform: {0}'.format(sys.platform))
+
+
+_UNIXCONFDIR = '/etc'
+_OS_RELEASE_BASENAME = 'os-release'
+
+#: Translation table for normalizing the "ID" attribute defined in os-release
+#: files, for use by the :func:`distro.id` method.
+#:
+#: * Key: Value as defined in the os-release file, translated to lower case,
+#:   with blanks translated to underscores.
+#:
+#: * Value: Normalized value.
+NORMALIZED_OS_ID = {}
+
+#: Translation table for normalizing the "Distributor ID" attribute returned by
+#: the lsb_release command, for use by the :func:`distro.id` method.
+#:
+#: * Key: Value as returned by the lsb_release command, translated to lower
+#:   case, with blanks translated to underscores.
+#:
+#: * Value: Normalized value.
+NORMALIZED_LSB_ID = {
+    'enterpriseenterprise': 'oracle',  # Oracle Enterprise Linux
+    'redhatenterpriseworkstation': 'rhel',  # RHEL 6.7
+}
+
+#: Translation table for normalizing the distro ID derived from the file name
+#: of distro release files, for use by the :func:`distro.id` method.
+#:
+#: * Key: Value as derived from the file name of a distro release file,
+#:   translated to lower case, with blanks translated to underscores.
+#:
+#: * Value: Normalized value.
+NORMALIZED_DISTRO_ID = {
+    'redhat': 'rhel',  # RHEL 6.x, 7.x
+}
+
+
+# Pattern for content of distro release file (reversed)
+_DISTRO_RELEASE_CONTENT_REVERSED_PATTERN = re.compile(
+    r'(?:[^)]*\)(.*)\()? *(?:STL )?([\d.+\-a-z]*\d) *(?:esaeler *)?(.+)')
+
+# Pattern for base file name of distro release file
+_DISTRO_RELEASE_BASENAME_PATTERN = re.compile(
+    r'(\w+)[-_](release|version)$')
+
+# Base file names to be ignored when searching for distro release file
+_DISTRO_RELEASE_IGNORE_BASENAMES = (
+    'debian_version',
+    'lsb-release',
+    'oem-release',
+    _OS_RELEASE_BASENAME,
+    'system-release'
+)
+
+
+def linux_distribution(full_distribution_name=True):
+    """
+    Return information about the current Linux distribution as a tuple
+    ``(id_name, version, codename)`` with items as follows:
+
+    * ``id_name``:  If *full_distribution_name* is false, the result of
+      :func:`distro.id`. Otherwise, the result of :func:`distro.name`.
+
+    * ``version``:  The result of :func:`distro.version`.
+
+    * ``codename``:  The result of :func:`distro.codename`.
+
+    The interface of this function is compatible with the original
+    :py:func:`platform.linux_distribution` function, supporting a subset of
+    its parameters.
+
+    The data it returns may not exactly be the same, because it uses more data
+    sources than the original function, and that may lead to different data if
+    the Linux distribution is not consistent across multiple data sources it
+    provides (there are indeed such distributions ...).
+
+    Another reason for differences is the fact that the :func:`distro.id`
+    method normalizes the distro ID string to a reliable machine-readable value
+    for a number of popular Linux distributions.
+    """
+    return _distroi.linux_distribution(full_distribution_name)
+
+
+def id():
+    """
+    Return the distro ID of the current Linux distribution, as a
+    machine-readable string.
+
+    For a number of Linux distributions, the returned distro ID value is
+    *reliable*, in the sense that it is documented and that it does not change
+    across releases of the distribution.
+
+    This package maintains the following reliable distro ID values:
+
+    ==============  =========================================
+    Distro ID       Distribution
+    ==============  =========================================
+    "ubuntu"        Ubuntu
+    "debian"        Debian
+    "rhel"          RedHat Enterprise Linux
+    "centos"        CentOS
+    "fedora"        Fedora
+    "sles"          SUSE Linux Enterprise Server
+    "opensuse"      openSUSE
+    "amazon"        Amazon Linux
+    "arch"          Arch Linux
+    "cloudlinux"    CloudLinux OS
+    "exherbo"       Exherbo Linux
+    "gentoo"        GenToo Linux
+    "ibm_powerkvm"  IBM PowerKVM
+    "kvmibm"        KVM for IBM z Systems
+    "linuxmint"     Linux Mint
+    "mageia"        Mageia
+    "mandriva"      Mandriva Linux
+    "parallels"     Parallels
+    "pidora"        Pidora
+    "raspbian"      Raspbian
+    "oracle"        Oracle Linux (and Oracle Enterprise Linux)
+    "scientific"    Scientific Linux
+    "slackware"     Slackware
+    "xenserver"     XenServer
+    ==============  =========================================
+
+    If you have a need to get distros for reliable IDs added into this set,
+    or if you find that the :func:`distro.id` function returns a different
+    distro ID for one of the listed distros, please create an issue in the
+    `distro issue tracker`_.
+
+    **Lookup hierarchy and transformations:**
+
+    First, the ID is obtained from the following sources, in the specified
+    order. The first available and non-empty value is used:
+
+    * the value of the "ID" attribute of the os-release file,
+
+    * the value of the "Distributor ID" attribute returned by the lsb_release
+      command,
+
+    * the first part of the file name of the distro release file,
+
+    The so determined ID value then passes the following transformations,
+    before it is returned by this method:
+
+    * it is translated to lower case,
+
+    * blanks (which should not be there anyway) are translated to underscores,
+
+    * a normalization of the ID is performed, based upon
+      `normalization tables`_. The purpose of this normalization is to ensure
+      that the ID is as reliable as possible, even across incompatible changes
+      in the Linux distributions. A common reason for an incompatible change is
+      the addition of an os-release file, or the addition of the lsb_release
+      command, with ID values that differ from what was previously determined
+      from the distro release file name.
+    """
+    return _distroi.id()
+
+
+def name(pretty=False):
+    """
+    Return the name of the current Linux distribution, as a human-readable
+    string.
+
+    If *pretty* is false, the name is returned without version or codename.
+    (e.g. "CentOS Linux")
+
+    If *pretty* is true, the version and codename are appended.
+    (e.g. "CentOS Linux 7.1.1503 (Core)")
+
+    **Lookup hierarchy:**
+
+    The name is obtained from the following sources, in the specified order.
+    The first available and non-empty value is used:
+
+    * If *pretty* is false:
+
+      - the value of the "NAME" attribute of the os-release file,
+
+      - the value of the "Distributor ID" attribute returned by the lsb_release
+        command,
+
+      - the value of the "<name>" field of the distro release file.
+
+    * If *pretty* is true:
+
+      - the value of the "PRETTY_NAME" attribute of the os-release file,
+
+      - the value of the "Description" attribute returned by the lsb_release
+        command,
+
+      - the value of the "<name>" field of the distro release file, appended
+        with the value of the pretty version ("<version_id>" and "<codename>"
+        fields) of the distro release file, if available.
+    """
+    return _distroi.name(pretty)
+
+
+def version(pretty=False, best=False):
+    """
+    Return the version of the current Linux distribution, as a human-readable
+    string.
+
+    If *pretty* is false, the version is returned without codename (e.g.
+    "7.0").
+
+    If *pretty* is true, the codename in parenthesis is appended, if the
+    codename is non-empty (e.g. "7.0 (Maipo)").
+
+    Some distributions provide version numbers with different precisions in
+    the different sources of distribution information. Examining the different
+    sources in a fixed priority order does not always yield the most precise
+    version (e.g. for Debian 8.2, or CentOS 7.1).
+
+    The *best* parameter can be used to control the approach for the returned
+    version:
+
+    If *best* is false, the first non-empty version number in priority order of
+    the examined sources is returned.
+
+    If *best* is true, the most precise version number out of all examined
+    sources is returned.
+
+    **Lookup hierarchy:**
+
+    In all cases, the version number is obtained from the following sources.
+    If *best* is false, this order represents the priority order:
+
+    * the value of the "VERSION_ID" attribute of the os-release file,
+    * the value of the "Release" attribute returned by the lsb_release
+      command,
+    * the version number parsed from the "<version_id>" field of the first line
+      of the distro release file,
+    * the version number parsed from the "PRETTY_NAME" attribute of the
+      os-release file, if it follows the format of the distro release files.
+    * the version number parsed from the "Description" attribute returned by
+      the lsb_release command, if it follows the format of the distro release
+      files.
+    """
+    return _distroi.version(pretty, best)
+
+
+def version_parts(best=False):
+    """
+    Return the version of the current Linux distribution as a tuple
+    ``(major, minor, build_number)`` with items as follows:
+
+    * ``major``:  The result of :func:`distro.major_version`.
+
+    * ``minor``:  The result of :func:`distro.minor_version`.
+
+    * ``build_number``:  The result of :func:`distro.build_number`.
+
+    For a description of the *best* parameter, see the :func:`distro.version`
+    method.
+    """
+    return _distroi.version_parts(best)
+
+
+def major_version(best=False):
+    """
+    Return the major version of the current Linux distribution, as a string,
+    if provided.
+    Otherwise, the empty string is returned. The major version is the first
+    part of the dot-separated version string.
+
+    For a description of the *best* parameter, see the :func:`distro.version`
+    method.
+    """
+    return _distroi.major_version(best)
+
+
+def minor_version(best=False):
+    """
+    Return the minor version of the current Linux distribution, as a string,
+    if provided.
+    Otherwise, the empty string is returned. The minor version is the second
+    part of the dot-separated version string.
+
+    For a description of the *best* parameter, see the :func:`distro.version`
+    method.
+    """
+    return _distroi.minor_version(best)
+
+
+def build_number(best=False):
+    """
+    Return the build number of the current Linux distribution, as a string,
+    if provided.
+    Otherwise, the empty string is returned. The build number is the third part
+    of the dot-separated version string.
+
+    For a description of the *best* parameter, see the :func:`distro.version`
+    method.
+    """
+    return _distroi.build_number(best)
+
+
+def like():
+    """
+    Return a space-separated list of distro IDs of distributions that are
+    closely related to the current Linux distribution in regards to packaging
+    and programming interfaces, for example distributions the current
+    distribution is a derivative from.
+
+    **Lookup hierarchy:**
+
+    This information item is only provided by the os-release file.
+    For details, see the description of the "ID_LIKE" attribute in the
+    `os-release man page
+    <http://www.freedesktop.org/software/systemd/man/os-release.html>`_.
+    """
+    return _distroi.like()
+
+
+def codename():
+    """
+    Return the codename for the release of the current Linux distribution,
+    as a string.
+
+    If the distribution does not have a codename, an empty string is returned.
+
+    Note that the returned codename is not always really a codename. For
+    example, openSUSE returns "x86_64". This function does not handle such
+    cases in any special way and just returns the string it finds, if any.
+
+    **Lookup hierarchy:**
+
+    * the codename within the "VERSION" attribute of the os-release file, if
+      provided,
+
+    * the value of the "Codename" attribute returned by the lsb_release
+      command,
+
+    * the value of the "<codename>" field of the distro release file.
+    """
+    return _distroi.codename()
+
+
+def info(pretty=False, best=False):
+    """
+    Return certain machine-readable information items about the current Linux
+    distribution in a dictionary, as shown in the following example:
+
+    .. sourcecode:: python
+
+        {
+            'id': 'rhel',
+            'version': '7.0',
+            'version_parts': {
+                'major': '7',
+                'minor': '0',
+                'build_number': ''
+            },
+            'like': 'fedora',
+            'codename': 'Maipo'
+        }
+
+    The dictionary structure and keys are always the same, regardless of which
+    information items are available in the underlying data sources. The values
+    for the various keys are as follows:
+
+    * ``id``:  The result of :func:`distro.id`.
+
+    * ``version``:  The result of :func:`distro.version`.
+
+    * ``version_parts -> major``:  The result of :func:`distro.major_version`.
+
+    * ``version_parts -> minor``:  The result of :func:`distro.minor_version`.
+
+    * ``version_parts -> build_number``:  The result of
+      :func:`distro.build_number`.
+
+    * ``like``:  The result of :func:`distro.like`.
+
+    * ``codename``:  The result of :func:`distro.codename`.
+
+    For a description of the *pretty* and *best* parameters, see the
+    :func:`distro.version` method.
+    """
+    return _distroi.info(pretty, best)
+
+
+def os_release_info():
+    """
+    Return a dictionary containing key-value pairs for the information items
+    from the os-release file data source of the current Linux distribution.
+
+    See `os-release file`_ for details about these information items.
+    """
+    return _distroi.os_release_info()
+
+
+def lsb_release_info():
+    """
+    Return a dictionary containing key-value pairs for the information items
+    from the lsb_release command data source of the current Linux distribution.
+
+    See `lsb_release command output`_ for details about these information
+    items.
+    """
+    return _distroi.lsb_release_info()
+
+
+def distro_release_info():
+    """
+    Return a dictionary containing key-value pairs for the information items
+    from the distro release file data source of the current Linux distribution.
+
+    See `distro release file`_ for details about these information items.
+    """
+    return _distroi.distro_release_info()
+
+
+def os_release_attr(attribute):
+    """
+    Return a single named information item from the os-release file data source
+    of the current Linux distribution.
+
+    Parameters:
+
+    * ``attribute`` (string): Key of the information item.
+
+    Returns:
+
+    * (string): Value of the information item, if the item exists.
+      The empty string, if the item does not exist.
+
+    See `os-release file`_ for details about these information items.
+    """
+    return _distroi.os_release_attr(attribute)
+
+
+def lsb_release_attr(attribute):
+    """
+    Return a single named information item from the lsb_release command output
+    data source of the current Linux distribution.
+
+    Parameters:
+
+    * ``attribute`` (string): Key of the information item.
+
+    Returns:
+
+    * (string): Value of the information item, if the item exists.
+      The empty string, if the item does not exist.
+
+    See `lsb_release command output`_ for details about these information
+    items.
+    """
+    return _distroi.lsb_release_attr(attribute)
+
+
+def distro_release_attr(attribute):
+    """
+    Return a single named information item from the distro release file
+    data source of the current Linux distribution.
+
+    Parameters:
+
+    * ``attribute`` (string): Key of the information item.
+
+    Returns:
+
+    * (string): Value of the information item, if the item exists.
+      The empty string, if the item does not exist.
+
+    See `distro release file`_ for details about these information items.
+    """
+    return _distroi.distro_release_attr(attribute)
+
+
+class LinuxDistribution(object):
+    """
+    Provides information about a Linux distribution.
+
+    This package creates a private module-global instance of this class with
+    default initialization arguments, that is used by the
+    `consolidated accessor functions`_ and `single source accessor functions`_.
+    By using default initialization arguments, that module-global instance
+    returns data about the current Linux distribution (i.e. the distro this
+    package runs on).
+
+    Normally, it is not necessary to create additional instances of this class.
+    However, in situations where control is needed over the exact data sources
+    that are used, instances of this class can be created with a specific
+    distro release file, or a specific os-release file, or without invoking the
+    lsb_release command.
+    """
+
+    def __init__(self,
+                 include_lsb=True,
+                 os_release_file='',
+                 distro_release_file=''):
+        """
+        The initialization method of this class gathers information from the
+        available data sources, and stores that in private instance attributes.
+        Subsequent access to the information items uses these private instance
+        attributes, so that the data sources are read only once.
+
+        Parameters:
+
+        * ``include_lsb`` (bool): Controls whether the
+          `lsb_release command output`_ is included as a data source.
+
+          If the lsb_release command is not available in the program execution
+          path, the data source for the lsb_release command will be empty.
+
+        * ``os_release_file`` (string): The path name of the
+          `os-release file`_ that is to be used as a data source.
+
+          An empty string (the default) will cause the default path name to
+          be used (see `os-release file`_ for details).
+
+          If the specified or defaulted os-release file does not exist, the
+          data source for the os-release file will be empty.
+
+        * ``distro_release_file`` (string): The path name of the
+          `distro release file`_ that is to be used as a data source.
+
+          An empty string (the default) will cause a default search algorithm
+          to be used (see `distro release file`_ for details).
+
+          If the specified distro release file does not exist, or if no default
+          distro release file can be found, the data source for the distro
+          release file will be empty.
+
+        Public instance attributes:
+
+        * ``os_release_file`` (string): The path name of the
+          `os-release file`_ that is actually used as a data source. The
+          empty string if no distro release file is used as a data source.
+
+        * ``distro_release_file`` (string): The path name of the
+          `distro release file`_ that is actually used as a data source. The
+          empty string if no distro release file is used as a data source.
+
+        Raises:
+
+        * :py:exc:`IOError`: Some I/O issue with an os-release file or distro
+          release file.
+
+        * :py:exc:`subprocess.CalledProcessError`: The lsb_release command had
+          some issue (other than not being available in the program execution
+          path).
+
+        * :py:exc:`UnicodeError`: A data source has unexpected characters or
+          uses an unexpected encoding.
+        """
+        self.os_release_file = os_release_file or \
+            os.path.join(_UNIXCONFDIR, _OS_RELEASE_BASENAME)
+        self.distro_release_file = distro_release_file or ''  # updated later
+        self._os_release_info = self._os_release_info()
+        self._lsb_release_info = self._lsb_release_info() \
+            if include_lsb else {}
+        self._distro_release_info = self._distro_release_info()
+
+    def __repr__(self):
+        return \
+            "LinuxDistribution(" \
+            "os_release_file={0!r}, " \
+            "distro_release_file={1!r}, " \
+            "_os_release_info={2!r}, " \
+            "_lsb_release_info={3!r}, " \
+            "_distro_release_info={4!r})".format(
+                self.os_release_file,
+                self.distro_release_file,
+                self._os_release_info,
+                self._lsb_release_info,
+                self._distro_release_info)
+
+    def linux_distribution(self, full_distribution_name=True):
+        """
+        Return information about the Linux distribution that is compatible
+        with Python's :func:`platform.linux_distribution`, supporting a subset
+        of its parameters.
+
+        For details, see :func:`distro.linux_distribution`.
+        """
+        return (
+            self.name() if full_distribution_name else self.id(),
+            self.version(),
+            self.codename()
+        )
+
+    def id(self):
+        """
+        Return the distro ID of the Linux distribution, as a string.
+
+        For details, see :func:`distro.id`.
+        """
+        distro_id = self.os_release_attr('id')
+        if distro_id:
+            distro_id = distro_id.lower().replace(' ', '_')
+            return NORMALIZED_OS_ID.get(distro_id, distro_id)
+
+        distro_id = self.lsb_release_attr('distributor_id')
+        if distro_id:
+            distro_id = distro_id.lower().replace(' ', '_')
+            return NORMALIZED_LSB_ID.get(distro_id, distro_id)
+
+        distro_id = self.distro_release_attr('id')
+        if distro_id:
+            distro_id = distro_id.lower().replace(' ', '_')
+            return NORMALIZED_DISTRO_ID.get(distro_id, distro_id)
+
+        return ''
+
+    def name(self, pretty=False):
+        """
+        Return the name of the Linux distribution, as a string.
+
+        For details, see :func:`distro.name`.
+        """
+        name = self.os_release_attr('name') \
+            or self.lsb_release_attr('distributor_id') \
+            or self.distro_release_attr('name')
+        if pretty:
+            name = self.os_release_attr('pretty_name') \
+                or self.lsb_release_attr('description')
+            if not name:
+                name = self.distro_release_attr('name')
+                version = self.version(pretty=True)
+                if version:
+                    name = name + ' ' + version
+        return name or ''
+
+    def version(self, pretty=False, best=False):
+        """
+        Return the version of the Linux distribution, as a string.
+
+        For details, see :func:`distro.version`.
+        """
+        versions = [
+            self.os_release_attr('version_id'),
+            self.lsb_release_attr('release'),
+            self.distro_release_attr('version_id'),
+            self._parse_distro_release_content(
+                self.os_release_attr('pretty_name')).get('version_id', ''),
+            self._parse_distro_release_content(
+                self.lsb_release_attr('description')).get('version_id', '')
+        ]
+        version = ''
+        if best:
+            # This algorithm uses the last version in priority order that has
+            # the best precision. If the versions are not in conflict, that
+            # does not matter; otherwise, using the last one instead of the
+            # first one might be considered a surprise.
+            for v in versions:
+                if v.count(".") > version.count(".") or version == '':
+                    version = v
+        else:
+            for v in versions:
+                if v != '':
+                    version = v
+                    break
+        if pretty and version and self.codename():
+            version = u'{0} ({1})'.format(version, self.codename())
+        return version
+
+    def version_parts(self, best=False):
+        """
+        Return the version of the Linux distribution, as a tuple of version
+        numbers.
+
+        For details, see :func:`distro.version_parts`.
+        """
+        version_str = self.version(best=best)
+        if version_str:
+            g = re.compile(r'(\d+)\.?(\d+)?\.?(\d+)?')
+            m = g.match(version_str)
+            if m:
+                major, minor, build_number = m.groups()
+                return major, minor or '', build_number or ''
+        return '', '', ''
+
+    def major_version(self, best=False):
+        """
+        Return the major version number of the current distribution.
+
+        For details, see :func:`distro.major_version`.
+        """
+        return self.version_parts(best)[0]
+
+    def minor_version(self, best=False):
+        """
+        Return the minor version number of the Linux distribution.
+
+        For details, see :func:`distro.minor_version`.
+        """
+        return self.version_parts(best)[1]
+
+    def build_number(self, best=False):
+        """
+        Return the build number of the Linux distribution.
+
+        For details, see :func:`distro.build_number`.
+        """
+        return self.version_parts(best)[2]
+
+    def like(self):
+        """
+        Return the IDs of distributions that are like the Linux distribution.
+
+        For details, see :func:`distro.like`.
+        """
+        return self.os_release_attr('id_like') or ''
+
+    def codename(self):
+        """
+        Return the codename of the Linux distribution.
+
+        For details, see :func:`distro.codename`.
+        """
+        return self.os_release_attr('codename') \
+            or self.lsb_release_attr('codename') \
+            or self.distro_release_attr('codename') \
+            or ''
+
+    def info(self, pretty=False, best=False):
+        """
+        Return certain machine-readable information about the Linux
+        distribution.
+
+        For details, see :func:`distro.info`.
+        """
+        return dict(
+            id=self.id(),
+            version=self.version(pretty, best),
+            version_parts=dict(
+                major=self.major_version(best),
+                minor=self.minor_version(best),
+                build_number=self.build_number(best)
+            ),
+            like=self.like(),
+            codename=self.codename(),
+        )
+
+    def os_release_info(self):
+        """
+        Return a dictionary containing key-value pairs for the information
+        items from the os-release file data source of the Linux distribution.
+
+        For details, see :func:`distro.os_release_info`.
+        """
+        return self._os_release_info
+
+    def lsb_release_info(self):
+        """
+        Return a dictionary containing key-value pairs for the information
+        items from the lsb_release command data source of the Linux
+        distribution.
+
+        For details, see :func:`distro.lsb_release_info`.
+        """
+        return self._lsb_release_info
+
+    def distro_release_info(self):
+        """
+        Return a dictionary containing key-value pairs for the information
+        items from the distro release file data source of the Linux
+        distribution.
+
+        For details, see :func:`distro.distro_release_info`.
+        """
+        return self._distro_release_info
+
+    def os_release_attr(self, attribute):
+        """
+        Return a single named information item from the os-release file data
+        source of the Linux distribution.
+
+        For details, see :func:`distro.os_release_attr`.
+        """
+        return self._os_release_info.get(attribute, '')
+
+    def lsb_release_attr(self, attribute):
+        """
+        Return a single named information item from the lsb_release command
+        output data source of the Linux distribution.
+
+        For details, see :func:`distro.lsb_release_attr`.
+        """
+        return self._lsb_release_info.get(attribute, '')
+
+    def distro_release_attr(self, attribute):
+        """
+        Return a single named information item from the distro release file
+        data source of the Linux distribution.
+
+        For details, see :func:`distro.distro_release_attr`.
+        """
+        return self._distro_release_info.get(attribute, '')
+
+    def _os_release_info(self):
+        """
+        Get the information items from the specified os-release file.
+
+        Returns:
+            A dictionary containing all information items.
+        """
+        if os.path.isfile(self.os_release_file):
+            with open(self.os_release_file, 'r') as f:
+                return self._parse_os_release_content(f)
+        return {}
+
+    @staticmethod
+    def _parse_os_release_content(lines):
+        """
+        Parse the lines of an os-release file.
+
+        Parameters:
+
+        * lines: Iterable through the lines in the os-release file.
+                 Each line must be a unicode string or a UTF-8 encoded byte
+                 string.
+
+        Returns:
+            A dictionary containing all information items.
+        """
+        props = {}
+        lexer = shlex.shlex(lines, posix=True)
+        lexer.whitespace_split = True
+
+        # The shlex module defines its `wordchars` variable using literals,
+        # making it dependent on the encoding of the Python source file.
+        # In Python 2.6 and 2.7, the shlex source file is encoded in
+        # 'iso-8859-1', and the `wordchars` variable is defined as a byte
+        # string. This causes a UnicodeDecodeError to be raised when the
+        # parsed content is a unicode object. The following fix resolves that
+        # (... but it should be fixed in shlex...):
+        if sys.version_info[0] == 2 and isinstance(lexer.wordchars, bytes):
+            lexer.wordchars = lexer.wordchars.decode('iso-8859-1')
+
+        tokens = list(lexer)
+        for token in tokens:
+            # At this point, all shell-like parsing has been done (i.e.
+            # comments processed, quotes and backslash escape sequences
+            # processed, multi-line values assembled, trailing newlines
+            # stripped, etc.), so the tokens are now either:
+            # * variable assignments: var=value
+            # * commands or their arguments (not allowed in os-release)
+            if '=' in token:
+                k, v = token.split('=', 1)
+                if isinstance(v, bytes):
+                    v = v.decode('utf-8')
+                props[k.lower()] = v
+                if k == 'VERSION':
+                    # this handles cases in which the codename is in
+                    # the `(CODENAME)` (rhel, centos, fedora) format
+                    # or in the `, CODENAME` format (Ubuntu).
+                    codename = re.search(r'(\(\D+\))|,(\s+)?\D+', v)
+                    if codename:
+                        codename = codename.group()
+                        codename = codename.strip('()')
+                        codename = codename.strip(',')
+                        codename = codename.strip()
+                        # codename appears within paranthese.
+                        props['codename'] = codename
+                    else:
+                        props['codename'] = ''
+            else:
+                # Ignore any tokens that are not variable assignments
+                pass
+        return props
+
+    def _lsb_release_info(self):
+        """
+        Get the information items from the lsb_release command output.
+
+        Returns:
+            A dictionary containing all information items.
+        """
+        cmd = 'lsb_release -a'
+        p = subprocess.Popen(
+            cmd,
+            shell=True,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE)
+        out, err = p.communicate()
+        out, err = out.decode('ascii'), err.decode('ascii')
+        rc = p.returncode
+        if rc == 0:
+            content = out.splitlines()
+            return self._parse_lsb_release_content(content)
+        elif rc == 127:  # Command not found
+            return {}
+        else:
+            if sys.version_info[:2] >= (3, 5):
+                raise subprocess.CalledProcessError(rc, cmd, out, err)
+            elif sys.version_info[:2] >= (2, 7):
+                raise subprocess.CalledProcessError(rc, cmd, out)
+            elif sys.version_info[:2] == (2, 6):
+                raise subprocess.CalledProcessError(rc, cmd)
+
+    @staticmethod
+    def _parse_lsb_release_content(lines):
+        """
+        Parse the output of the lsb_release command.
+
+        Parameters:
+
+        * lines: Iterable through the lines of the lsb_release output.
+                 Each line must be a unicode string or a UTF-8 encoded byte
+                 string.
+
+        Returns:
+            A dictionary containing all information items.
+        """
+        props = {}
+        for line in lines:
+            if isinstance(line, bytes):
+                line = line.decode('utf-8')
+            kv = line.strip('\n').split(':', 1)
+            if len(kv) != 2:
+                # Ignore lines without colon.
+                continue
+            k, v = kv
+            props.update({k.replace(' ', '_').lower(): v.strip()})
+        return props
+
+    def _distro_release_info(self):
+        """
+        Get the information items from the specified distro release file.
+
+        Returns:
+            A dictionary containing all information items.
+        """
+        if self.distro_release_file:
+            # If it was specified, we use it and parse what we can, even if
+            # its file name or content does not match the expected pattern.
+            distro_info = self._parse_distro_release_file(
+                self.distro_release_file)
+            basename = os.path.basename(self.distro_release_file)
+            # The file name pattern for user-specified distro release files
+            # is somewhat more tolerant (compared to when searching for the
+            # file), because we want to use what was specified as best as
+            # possible.
+            match = _DISTRO_RELEASE_BASENAME_PATTERN.match(basename)
+            if match:
+                distro_info['id'] = match.group(1)
+            return distro_info
+        else:
+            basenames = os.listdir(_UNIXCONFDIR)
+            # We sort for repeatability in cases where there are multiple
+            # distro specific files; e.g. CentOS, Oracle, Enterprise all
+            # containing `redhat-release` on top of their own.
+            basenames.sort()
+            for basename in basenames:
+                if basename in _DISTRO_RELEASE_IGNORE_BASENAMES:
+                    continue
+                match = _DISTRO_RELEASE_BASENAME_PATTERN.match(basename)
+                if match:
+                    filepath = os.path.join(_UNIXCONFDIR, basename)
+                    distro_info = self._parse_distro_release_file(filepath)
+                    if 'name' in distro_info:
+                        # The name is always present if the pattern matches
+                        self.distro_release_file = filepath
+                        distro_info['id'] = match.group(1)
+                        return distro_info
+            return {}
+
+    def _parse_distro_release_file(self, filepath):
+        """
+        Parse a distro release file.
+
+        Parameters:
+
+        * filepath: Path name of the distro release file.
+
+        Returns:
+            A dictionary containing all information items.
+        """
+        if os.path.isfile(filepath):
+            with open(filepath, 'r') as fp:
+                # Only parse the first line. For instance, on SLES there
+                # are multiple lines. We don't want them...
+                return self._parse_distro_release_content(fp.readline())
+        return {}
+
+    @staticmethod
+    def _parse_distro_release_content(line):
+        """
+        Parse a line from a distro release file.
+
+        Parameters:
+        * line: Line from the distro release file. Must be a unicode string
+                or a UTF-8 encoded byte string.
+
+        Returns:
+            A dictionary containing all information items.
+        """
+        if isinstance(line, bytes):
+            line = line.decode('utf-8')
+        m = _DISTRO_RELEASE_CONTENT_REVERSED_PATTERN.match(
+            line.strip()[::-1])
+        distro_info = {}
+        if m:
+            distro_info['name'] = m.group(3)[::-1]   # regexp ensures non-None
+            if m.group(2):
+                distro_info['version_id'] = m.group(2)[::-1]
+            if m.group(1):
+                distro_info['codename'] = m.group(1)[::-1]
+        elif line:
+            distro_info['name'] = line.strip()
+        return distro_info
+
+
+_distroi = LinuxDistribution()
diff --git a/lib/spack/spack/operating_systems/linux_distro.py b/lib/spack/spack/operating_systems/linux_distro.py
index 6d70ae80b6..e18dab38fc 100644
--- a/lib/spack/spack/operating_systems/linux_distro.py
+++ b/lib/spack/spack/operating_systems/linux_distro.py
@@ -1,5 +1,5 @@
 import re
-import platform as py_platform
+from external.distro import linux_distribution
 from spack.architecture import OperatingSystem
 
 
@@ -12,8 +12,9 @@ class LinuxDistro(OperatingSystem):
     """
 
     def __init__(self):
-        distname, version, _ = py_platform.linux_distribution(
+        distname, version, _ = linux_distribution(
             full_distribution_name=False)
+        distname, version = str(distname), str(version)
 
         # Grabs major version from tuple on redhat; on other platforms
         # grab the first legal identifier in the version field.  On