Add more distro_name() & distro_family() functionality

patchwork/files.py

@@ -91,3 +91,10 @@ def _escape_for_regex(text):
     # Whereas single quotes should not be escaped
     regex = regex.replace(r"\'", "'")
     return regex
+
+def cat(path, runner=run):
+    """
+    Cat a file, returning its contents as a string.
+    """
+    with hide('stdout'):
+        return runner('cat "%(path)s"' % locals()).stdout

patchwork/info.py

@@ -1,5 +1,45 @@
+from collections import namedtuple
+
+from fabric.api import run
+from environment import has_binary
 from fabric.contrib.files import exists
+from files import cat
+
+
+REDHAT_FAMILY_DISTROS = "rhel fedora centos amazon".split()
+DEBIAN_FAMILY_DISTROS = "ubuntu debian".split()
 
+# Holder struct for lsb_release info.
+lsb_release_info=namedtuple("lsb_release_info", 
+        ["lsb_version",
+        "distributor",
+        "description",
+        "release_version",
+        "codename"])
+
+def lsb_release():
+    """
+    Get Linux Standard Base distro information, if available.
+    http://refspecs.linuxbase.org/LSB_3.1.1/LSB-Core-generic/LSB-Core-generic/lsbrelease.html
+
+    Returns None if unavailable, or else a lsb_release_info object with the
+    following string attributes:
+        lsb_version
+        distributor
+        description
+        release_version
+        codename
+    """
+    if not has_binary('lsb_release'):
+        return None
+    def lsb_attr(flagname):
+        return run('lsb_release --short --%s' % flagname).stdout
+    result = lsb_release_info(lsb_attr('version'),
+            lsb_attr('id'),
+            lsb_attr('description'),
+            lsb_attr('release'),
+            lsb_attr('codename'))
+    return result
 
 def distro_name():
     """
@@ -11,10 +51,23 @@ def distro_name():
     * ``fedora``
     * ``rhel``
     * ``centos``
+    * ``amazon``
     * ``ubuntu``
     * ``debian``
     * ``other``
     """
+    lsb_info = lsb_release()
+    if lsb_info:
+        try:
+            distributor_names = {
+                    'Ubuntu': 'ubuntu',
+                    'Debian': 'debian',
+                    'AmazonAMI': 'amazon',
+            }
+            return distributor_names[lsb_info.distributor]
+        except KeyError:
+            pass
+
     sentinel_files = {
         'fedora': ('fedora-release',),
         'centos': ('centos-release',),
@@ -23,6 +76,20 @@ def distro_name():
         for sentinel in sentinels:
             if exists('/etc/%s' % sentinel):
                 return name
+
+    # Redhat-like distros erratically include /etc/redhat-release
+    # instead of distro-specific files.
+    redhat_release_file = '/etc/redhat-release'
+    if exists(redhat_release_file):
+        redhat_release_content = cat(redhat_release_file)
+        for distro in REDHAT_FAMILY_DISTROS:
+            if distro in redhat_release_content.lower():
+                return distro
+
+    system_release_file = '/etc/system-release'
+    if exists(system_release_file) and 'Amazon Linux' in cat(system_release_file):
+        return 'amazon'
+
     return "other"
 
 
@@ -35,15 +102,21 @@ def distro_family():
     * ``debian``
     * ``redhat``
 
-    If the system falls outside these categories, its specific family or
-    release name will be returned instead.
+    If the system falls outside these categories, its discovered distro_name
+    will be returned instead (possibly ``other`` if its type couldn't be
+    determined).
     """
     families = {
         'debian': "debian ubuntu".split(),
-        'redhat': "rhel centos fedora".split()
+        'redhat': "rhel centos fedora amazon".split()
     }
     distro = distro_name()
     for family, members in families.iteritems():
         if distro in members:
             return family
+    # Even if we haven't been able to determine exact distro,
+    # we may be able to determine the overall family.
+    if distro == 'other':
+        if exists('/etc/debian_version'):
+            return 'debian'
     return distro

test/test_distro.py

@@ -0,0 +1,63 @@
+from patchwork import info
+import unittest
+from unittest import TestCase
+
+import mock
+from patchwork.info import lsb_release_info
+
+
+ubuntu1104_lsb_info = lsb_release_info('No LSB modules are available.',
+                    'Ubuntu',
+                    'Ubuntu 11.04',
+                    '11.04',
+                    'natty')
+amazon2012_03_lsb_info = lsb_release_info(':core-4.0-amd64:core-4.0-noarch:printing-4.0-amd64:printing-4.0-noarch',
+                    'AmazonAMI',
+                    'Amazon Linux AMI release 2012.03',
+                    '2012.03',
+                    'n/a')
+
+class DistroNameDetection(TestCase):
+    @mock.patch('patchwork.info.lsb_release')
+    @mock.patch('patchwork.info.run')
+    def test_ubuntu_detection_via_lsb_release(self, run, lsb_release):
+        lsb_release.return_value = ubuntu1104_lsb_info
+        self.assertEqual(info.distro_name(), 'ubuntu')
+        lsb_release.assert_called()
+        self.assertFalse(run.called)
+
+    @mock.patch('patchwork.info.lsb_release')
+    @mock.patch('patchwork.info.run')
+    def test_amazon_detection_via_lsb_release(self, run, lsb_release):
+        lsb_release.return_value = amazon2012_03_lsb_info
+        self.assertEqual(info.distro_name(), 'amazon')
+        lsb_release.assert_called()
+        self.assertFalse(run.called)
+
+class DistroFamilyDetection(TestCase):
+    @mock.patch('patchwork.info.distro_name')
+    @mock.patch('patchwork.info.run')
+    def test_debian_family(self, run, distro_name_fxn):
+        for d in ('ubuntu', 'debian'):
+            distro_name_fxn.return_value = d
+            self.assertEqual('debian', info.distro_family())
+            self.assertFalse(run.called)
+
+    @mock.patch('patchwork.info.distro_name')
+    @mock.patch('patchwork.info.run')
+    def test_redhat_family(self, run, distro_name_fxn):
+        for d in ('redhat', 'centos', 'fedora', 'amazon'):
+            distro_name_fxn.return_value = d
+            self.assertEqual('redhat', info.distro_family())
+            self.assertFalse(run.called)
+
+    @mock.patch('patchwork.info.exists')
+    @mock.patch('patchwork.info.distro_name')
+    @mock.patch('patchwork.info.run')
+    def test_family_inference(self, run, distro_name_fxn, file_exists):
+        """If debian_version exists, then it should be picked up as debian-family,
+        even if exact type couldn't be worked out."""
+        distro_name_fxn.return_value = 'other'
+        file_exists.side_effect = lambda s: s == '/etc/debian_version'
+        self.assertEqual('debian', info.distro_family())
+