Consolidate systemd detection logic (#81809)

* Add logic to consider the canary location for systemd files

Fixes: #80975

Signed-off-by: Abhijeet Kasurde <akasurde@redhat.com>

changelogs/fragments/80975-systemd-detect.yml

@@ -0,0 +1,3 @@
+---
+bugfixes:
+  - Consolidate systemd detection logic into one place (https://github.com/ansible/ansible/issues/80975).

lib/ansible/module_utils/service.py

@@ -110,8 +110,8 @@ def fail_if_missing(module, found, service, msg=''):
     This function will return an error or exit gracefully depending on check mode status
     and if the service is missing or not.
 
-    :arg module: is an  AnsibleModule object, used for it's utility methods
-    :arg found: boolean indicating if services was found or not
+    :arg module: is an AnsibleModule object, used for it's utility methods
+    :arg found: boolean indicating if services were found or not
     :arg service: name of service
     :kw msg: extra info to append to error/success msg when missing
     '''
@@ -165,7 +165,7 @@ def daemonize(module, cmd):
     '''
     Execute a command while detaching as a daemon, returns rc, stdout, and stderr.
 
-    :arg module: is an  AnsibleModule object, used for it's utility methods
+    :arg module: is an AnsibleModule object, used for it's utility methods
     :arg cmd: is a list or string representing the command and options to run
 
     This is complex because daemonization is hard for people.
@@ -274,3 +274,30 @@ def check_ps(module, pattern):
             if pattern in line:
                 return True
     return False
+
+
+def is_systemd_managed(module):
+    """
+    Find out if the machine supports systemd or not
+    :arg module: is an AnsibleModule object, used for it's utility methods
+
+    Returns True if the system supports systemd, False if not.
+    """
+    # tools must be installed
+    if module.get_bin_path('systemctl'):
+        # This should show if systemd is the boot init system, if checking init failed to mark as systemd
+        # these mirror systemd's own sd_boot test http://www.freedesktop.org/software/systemd/man/sd_booted.html
+        for canary in ["/run/systemd/system/", "/dev/.run/systemd/", "/dev/.systemd/"]:
+            if os.path.exists(canary):
+                return True
+
+        # If all else fails, check if init is the systemd command, using comm as cmdline could be symlink
+        try:
+            with open('/proc/1/comm', 'r') as init_proc:
+                init = init_proc.readline().strip()
+                return init == 'systemd'
+        except IOError:
+            # If comm doesn't exist, old kernel, no systemd
+            return False
+
+    return False

lib/ansible/modules/service.py

@@ -179,7 +179,7 @@ from ansible.module_utils.common.text.converters import to_bytes, to_text
 from ansible.module_utils.basic import AnsibleModule
 from ansible.module_utils.common.locale import get_best_parsable_locale
 from ansible.module_utils.common.sys_info import get_platform_subclass
-from ansible.module_utils.service import fail_if_missing
+from ansible.module_utils.service import fail_if_missing, is_systemd_managed
 from ansible.module_utils.six import PY2, b
 
 
@@ -484,24 +484,7 @@ class LinuxService(Service):
 
             # tools must be installed
             if location.get('systemctl', False):
-
-                # this should show if systemd is the boot init system
-                # these mirror systemd's own sd_boot test http://www.freedesktop.org/software/systemd/man/sd_booted.html
-                for canary in ["/run/systemd/system/", "/dev/.run/systemd/", "/dev/.systemd/"]:
-                    if os.path.exists(canary):
-                        return True
-
-                # If all else fails, check if init is the systemd command, using comm as cmdline could be symlink
-                try:
-                    f = open('/proc/1/comm', 'r')
-                except IOError:
-                    # If comm doesn't exist, old kernel, no systemd
-                    return False
-
-                for line in f:
-                    if 'systemd' in line:
-                        return True
-
+                return is_systemd_managed(self.module)
             return False
 
         # Locate a tool to enable/disable a service

lib/ansible/modules/service_facts.py

@@ -94,6 +94,7 @@ import platform
 import re
 from ansible.module_utils.basic import AnsibleModule
 from ansible.module_utils.common.locale import get_best_parsable_locale
+from ansible.module_utils.service import is_systemd_managed
 
 
 class BaseService(object):
@@ -244,16 +245,7 @@ class SystemctlScanService(BaseService):
     BAD_STATES = frozenset(['not-found', 'masked', 'failed'])
 
     def systemd_enabled(self):
-        # Check if init is the systemd command, using comm as cmdline could be symlink
-        try:
-            f = open('/proc/1/comm', 'r')
-        except IOError:
-            # If comm doesn't exist, old kernel, no systemd
-            return False
-        for line in f:
-            if 'systemd' in line:
-                return True
-        return False
+        return is_systemd_managed(self.module)
 
     def _list_from_units(self, systemctl_path, services):