[Policy] Consolidate check() across policies

There is a common theme for new policies to subclass an existing one and
just update the `check()` method. In almost all instances, the `check()`
method remains almost entirely the same, simply changing a release file
name or string.

Reduce repeating ourselves by consolidating this into the base
`LinuxPolicy.check()`, and leverage per-policy class attributes
`os_release_file`, `os_release_name`, and `os_release_id`. The first of
which will enable a policy if the specified file is found. Failing that,
`os_release_name` is used to check the `NAME` field in
`/etc/os-release`, and `os_release_id` is used to check the `ID` field
in the same file if the name pattern does not match (or is not set).

Note that we do _not_ check the `ID_LIKE` field.

This allows a policy to be defined with as little as something like the
following:

```
class MyPolicy(LinuxPolicy):
    distro = 'My Awesome Linux'
    vendor = 'Myself'
    os_release_file = '/etc/mylinux-release'
    os_release_name = 'MyLinux'
    os_release_id ='mynix'
```

Resolves: #1934

Signed-off-by: Jake Hunsaker <[email protected]>

sos/policies/__init__.py

@@ -42,6 +42,7 @@ def load(cache={}, sysroot=None, init=None, probe_runtime=True,
                 cache['policy'] = policy(sysroot=sysroot, init=init,
                                          probe_runtime=probe_runtime,
                                          remote_exec=remote_exec)
+                break
 
     if sys.platform != 'linux':
         raise Exception("SoS is not supported on this platform")

sos/policies/distros/__init__.py

@@ -40,6 +40,7 @@
 except ImportError:
     BOTO3_LOADED = False
 
+OS_RELEASE = "/etc/os-release"
 # Container environment variables for detecting if we're in a container
 ENV_CONTAINER = 'container'
 ENV_HOST_SYSROOT = 'HOST'
@@ -53,6 +54,11 @@ class LinuxPolicy(Policy):
     vendor = "None"
     PATH = "/bin:/sbin:/usr/bin:/usr/sbin"
     init = None
+    # the following will be used, in order, as part of check() to validate that
+    # we are running on a particular distro
+    os_release_file = ''
+    os_release_name = ''
+    os_release_id = ''
     # _ prefixed class attrs are used for storing any vendor-defined defaults
     # the non-prefixed attrs are used by the upload methods, and will be set
     # to the cmdline/config file values, if provided. If not provided, then
@@ -145,7 +151,29 @@ def check(cls, remote=''):
         This function is responsible for determining if the underlying system
         is supported by this policy.
         """
-        raise NotImplementedError
+        def _check_release(content):
+            _matches = [cls.distro]
+            if isinstance(cls.os_release_name, list):
+                _matches.extend(cls.os_release_name)
+            else:
+                _matches.append(cls.os_release_name)
+            if cls.os_release_id:
+                _matches.append(cls.os_release_id)
+            for line in content.splitlines():
+                if line.startswith(('NAME=', 'ID=')):
+                    _distro = line.split('=')[1:][0].strip("\"'")
+                    if _distro in _matches:
+                        return True
+            return False
+
+        if remote:
+            return _check_release(remote)
+        # use the os-specific file primarily
+        if os.path.isfile(cls.os_release_file):
+            return True
+        # next check os-release for a NAME or ID value we expect
+        with open(OS_RELEASE, "r", encoding='utf-8') as f:
+            return _check_release(f.read())
 
     def kernel_version(self):
         return self.release

sos/policies/distros/almalinux.py

@@ -8,13 +8,15 @@
 #
 # See the LICENSE file in the source distribution for further information.
 
-import os
-from sos.policies.distros.redhat import RedHatPolicy, OS_RELEASE
+from sos.policies.distros.redhat import RedHatPolicy
 
 
 class AlmaLinuxPolicy(RedHatPolicy):
     distro = "AlmaLinux"
     vendor = "AlmaLinux OS Foundation"
+    os_release_file = '/etc/almalinux-release'
+    os_release_name = 'AlmaLinux'
+
     vendor_urls = [
         ('Distribution Website', 'https://www.almalinux.org/'),
         ('Commercial Support', 'https://tuxcare.com/linux-support-services/')
@@ -26,21 +28,4 @@ def __init__(self, sysroot=None, init=None, probe_runtime=True,
                          probe_runtime=probe_runtime,
                          remote_exec=remote_exec)
 
-    @classmethod
-    def check(cls, remote=''):
-        if remote:
-            return cls.distro in remote
-
-        if not os.path.isfile('/etc/almalinux-release'):
-            return False
-
-        if os.path.exists(OS_RELEASE):
-            with open(OS_RELEASE, 'r', encoding='utf-8') as f:
-                for line in f:
-                    if line.startswith('NAME'):
-                        if 'AlmaLinux' in line:
-                            return True
-
-        return False
-
 # vim: set et ts=4 sw=4 :

sos/policies/distros/amazon.py

@@ -8,36 +8,21 @@
 #
 # See the LICENSE file in the source distribution for further information.
 
-import os
-from sos.policies.distros.redhat import RedHatPolicy, OS_RELEASE
+from sos.policies.distros.redhat import RedHatPolicy
 
 
 class AmazonPolicy(RedHatPolicy):
 
     distro = "Amazon Linux"
     vendor = "Amazon"
     vendor_urls = [('Distribution Website', 'https://aws.amazon.com')]
+    os_release_file = ''
+    os_release_name = 'Amazon Linux'
 
     def __init__(self, sysroot=None, init=None, probe_runtime=True,
                  remote_exec=None):
         super().__init__(sysroot=sysroot, init=init,
                          probe_runtime=probe_runtime,
                          remote_exec=remote_exec)
 
-    @classmethod
-    def check(cls, remote=''):
-
-        if remote:
-            return cls.distro in remote
-
-        if not os.path.exists(OS_RELEASE):
-            return False
-
-        with open(OS_RELEASE, 'r', encoding='utf-8') as f:
-            for line in f:
-                if line.startswith('NAME'):
-                    if 'Amazon Linux' in line:
-                        return True
-        return False
-
 # vim: set et ts=4 sw=4 :

sos/policies/distros/anolis.py

@@ -6,41 +6,21 @@
 #
 # See the LICENSE file in the source distribution for further information.
 
-import os
-from sos.policies.distros.redhat import RedHatPolicy, OS_RELEASE
+from sos.policies.distros.redhat import RedHatPolicy
 
 
 class AnolisPolicy(RedHatPolicy):
 
     distro = "Anolis OS"
     vendor = "The OpenAnolis Project"
     vendor_urls = [('Distribution Website', 'https://openanolis.org/')]
+    os_release_file = '/etc/anolis-release'
+    os_release_name = 'Anolis OS'
 
     def __init__(self, sysroot=None, init=None, probe_runtime=True,
                  remote_exec=None):
         super().__init__(sysroot=sysroot, init=init,
                          probe_runtime=probe_runtime,
                          remote_exec=remote_exec)
 
-    @classmethod
-    def check(cls, remote=''):
-
-        if remote:
-            return cls.distro in remote
-
-        # Return False if /etc/os-release is missing
-        if not os.path.exists(OS_RELEASE):
-            return False
-
-        # Return False if /etc/anolis-release is missing
-        if not os.path.isfile('/etc/anolis-release'):
-            return False
-
-        with open(OS_RELEASE, 'r', encoding='utf-8') as f:
-            for line in f:
-                if line.startswith('NAME'):
-                    if 'Anolis OS' in line:
-                        return True
-        return False
-
 # vim: set et ts=4 sw=4 :

sos/policies/distros/azure.py

@@ -8,9 +8,8 @@
 #
 # See the LICENSE file in the source distribution for further information.
 
-import os
 from sos.report.plugins import AzurePlugin
-from sos.policies.distros.redhat import RedHatPolicy, OS_RELEASE
+from sos.policies.distros.redhat import RedHatPolicy
 
 
 class AzurePolicy(RedHatPolicy):
@@ -20,6 +19,10 @@ class AzurePolicy(RedHatPolicy):
     vendor_urls = [
         ('Distribution Website', 'https://github.com/microsoft/azurelinux')
     ]
+    os_release_name = [
+        'Common Base Linux Mariner',
+        'Microsoft Azure Linux'
+    ]
 
     def __init__(self, sysroot=None, init=None, probe_runtime=True,
                  remote_exec=None):
@@ -28,22 +31,4 @@ def __init__(self, sysroot=None, init=None, probe_runtime=True,
                          remote_exec=remote_exec)
         self.valid_subclasses += [AzurePlugin]
 
-    @classmethod
-    def check(cls, remote=''):
-
-        if remote:
-            return cls.distro in remote
-
-        if not os.path.exists(OS_RELEASE):
-            return False
-
-        with open(OS_RELEASE, 'r', encoding='utf-8') as f:
-            for line in f:
-                if line.startswith('NAME'):
-                    if 'Common Base Linux Mariner' in line:
-                        return True
-                    if 'Microsoft Azure Linux' in line:
-                        return True
-        return False
-
 # vim: set et ts=4 sw=4 :

sos/policies/distros/circle.py

@@ -8,42 +8,21 @@
 #
 # See the LICENSE file in the source distribution for further information.
 
-import os
-from sos.policies.distros.redhat import RedHatPolicy, OS_RELEASE
+from sos.policies.distros.redhat import RedHatPolicy
 
 
 class CirclePolicy(RedHatPolicy):
 
     distro = "Circle Linux"
     vendor = "The Circle Linux Project"
     vendor_urls = [('Distribution Website', 'https://cclinux.org')]
+    os_release_file = '/etc/circle-release'
+    os_release_name = 'Circle Linux'
 
     def __init__(self, sysroot=None, init=None, probe_runtime=True,
                  remote_exec=None):
         super().__init__(sysroot=sysroot, init=init,
                          probe_runtime=probe_runtime,
                          remote_exec=remote_exec)
 
-    @classmethod
-    def check(cls, remote=''):
-
-        if remote:
-            return cls.distro in remote
-
-        # Return False if /etc/os-release is missing
-        if not os.path.exists(OS_RELEASE):
-            return False
-
-        # Return False if /etc/circle-release is missing
-        if not os.path.isfile('/etc/circle-release'):
-            return False
-
-        with open(OS_RELEASE, 'r', encoding='utf-8') as f:
-            for line in f:
-                if line.startswith('NAME'):
-                    if 'Circle Linux' in line:
-                        return True
-
-        return False
-
 # vim: set et ts=4 sw=4 :

sos/policies/distros/cloudlinux.py

@@ -8,8 +8,7 @@
 #
 # See the LICENSE file in the source distribution for further information.
 
-import os
-from sos.policies.distros.redhat import RedHatPolicy, OS_RELEASE
+from sos.policies.distros.redhat import RedHatPolicy
 
 
 class CloudLinuxPolicy(RedHatPolicy):
@@ -19,28 +18,13 @@ class CloudLinuxPolicy(RedHatPolicy):
         ('Distribution Website', 'https://www.cloudlinux.com/'),
         ('Commercial Support', 'https://www.cloudlinux.com/')
     ]
+    os_release_file = '/etc/cloudlinux-release'
+    os_release_name = 'CloudLinux'
 
     def __init__(self, sysroot=None, init=None, probe_runtime=True,
                  remote_exec=None):
         super().__init__(sysroot=sysroot, init=init,
                          probe_runtime=probe_runtime,
                          remote_exec=remote_exec)
 
-    @classmethod
-    def check(cls, remote=''):
-        if remote:
-            return cls.distro in remote
-
-        if not os.path.isfile('/etc/cloudlinux-release'):
-            return False
-
-        if os.path.exists(OS_RELEASE):
-            with open(OS_RELEASE, 'r', encoding='utf-8') as f:
-                for line in f:
-                    if line.startswith('NAME'):
-                        if 'CloudLinux' in line:
-                            return True
-
-        return False
-
 # vim: set et ts=4 sw=4 :

sos/policies/distros/cos.py

@@ -33,6 +33,8 @@ class CosPolicy(LinuxPolicy):
         ('Distribution Website',
          'https://cloud.google.com/container-optimized-os/')
     ]
+    os_release_name = 'Container-Optimized OS'
+    os_release_id = 'cos'
     valid_subclasses = [CosPlugin, IndependentPlugin]
     PATH = "/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin"
 
@@ -43,17 +45,4 @@ def __init__(self, sysroot=None, init=None, probe_runtime=True,
                          remote_exec=remote_exec)
         self.valid_subclasses += [CosPolicy]
 
-    @classmethod
-    def check(cls, remote=''):
-        if remote:
-            return cls.distro in remote
-
-        try:
-            with open('/etc/os-release', 'r', encoding='utf-8') as fp:
-                os_release = dict(line.strip().split('=') for line in fp
-                                  if not _blank_or_comment(line))
-                return os_release['ID'] == 'cos'
-        except (IOError, KeyError):
-            return False
-
 # vim: set et ts=4 sw=4 :

sos/policies/distros/debian.py

@@ -6,8 +6,6 @@
 #
 # See the LICENSE file in the source distribution for further information.
 
-import os
-
 from sos.report.plugins import DebianPlugin
 from sos.policies.distros import LinuxPolicy
 from sos.policies.package_managers.dpkg import DpkgPackageManager
@@ -17,6 +15,7 @@ class DebianPolicy(LinuxPolicy):
     distro = "Debian"
     vendor = "the Debian project"
     vendor_urls = [('Community Website', 'https://www.debian.org/')]
+    os_release_file = '/etc/debian_version'
     name_pattern = 'friendly'
     valid_subclasses = [DebianPlugin]
     PATH = "/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games" \
@@ -50,16 +49,6 @@ def _get_pkg_name_for_binary(self, binary):
             "xz": "xz-utils"
         }.get(binary, binary)
 
-    @classmethod
-    def check(cls, remote=''):
-        """This method checks to see if we are running on Debian.
-           It returns True or False."""
-
-        if remote:
-            return cls.distro in remote
-
-        return os.path.isfile('/etc/debian_version')
-
     def dist_version(self):
         try:
             with open('/etc/os-release', 'r', encoding='utf-8') as fp: