systemd_status: add support to monitor user services

Also add support to ignore specific services.

plugins/systemd/systemd_status

@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 # pylint: disable=invalid-name
 # pylint: enable=invalid-name
+# pylint: disable=consider-using-f-string
 
 """Munin plugin to monitor systemd service status.
 
@@ -20,6 +21,21 @@ No configuration is required for this plugin.
 Warning level for systemd "failed" state is set to 0:0. If any of the services
 enters "failed" state, Munin will emit warning.
 
+Single service can be ignored by configuring it's value to "0":
+
+  [systemd_status]
+  env.fwupd_refresh_service 0
+
+Normally this plugin monitors global system services. User services can be
+monitored by manually adding softlink and config:
+
+  ln -s /usr/share/munin/plugins/systemd_status \
+    /etc/munin/plugins/systemd_status_b
+
+  [systemd_status_b]
+  user b
+  env.monitor_user yes
+
 =head1 AUTHOR
 
 Kim B. Heino <b@bbbs.net>
@@ -38,9 +54,11 @@ GPLv2
 """
 
 import os
+import pwd
 import re
 import subprocess
 import sys
+import unicodedata
 
 
 STATES = (
@@ -55,10 +73,26 @@ STATES = (
     'mounted',
 )
 
+USER = os.environ.get('monitor_user') in ('yes', '1')
+
+
+def safename(name):
+    """Return safe variable name."""
+    # Convert ä->a as isalpha('ä') is true
+    value = unicodedata.normalize('NFKD', name)
+    value = value.encode('ASCII', 'ignore').decode('utf-8')
+
+    # Remove non-alphanumeric chars
+    return ''.join(char.lower() if char.isalnum() else '_' for char in value)
+
 
 def config():
     """Autoconfig values."""
-    print('graph_title systemd services')
+    if USER:
+        print('graph_title systemd services for {}'.format(
+            pwd.getpwuid(os.geteuid())[0]))
+    else:
+        print('graph_title systemd services')
     print('graph_vlabel Services')
     print('graph_category processes')
     print('graph_args --base 1000 --lower-limit 0')
@@ -75,33 +109,50 @@ def fetch():
     """Print runtime values."""
     # Get data
     try:
-        # deb9/py3.5 doesn't have encoding parameter in subprocess
-        output = subprocess.check_output(['/bin/systemctl', 'list-units'])
+        output = subprocess.check_output(['systemctl', 'list-units'] +
+                                         (['--user'] if USER else []),
+                                         encoding='utf-8')
     except (OSError, subprocess.CalledProcessError):
         return
-    output = output.decode('utf-8', 'ignore')
 
     # Parse data
     states = {state: 0 for state in STATES}
     for line in output.splitlines():
         token = line.split()
+        if token and len(token[0]) < 3:  # Skip failed-bullet
+            token = token[1:]
         if len(token) < 4:
             continue
-        if len(token[0]) < 3:  # Skip failed-bullet
-            token = token[1:]
-        if token[0].endswith('.scope'):
+        service = token[0]
+        state = token[3]
+        if service.endswith('.scope'):
             continue  # Ignore scopes
-        if re.match(r'user.*@\d+\.service', token[0]):
+        if re.match(r'user.*@\d+\.service', service):
             continue  # These fail randomly in older systemd
-        if token[3] in states:
-            states[token[3]] = states[token[3]] + 1
+        if state in states:
+            value = 1
+            if state == 'failed':
+                value = int(os.environ.get(safename(service), 1))
+            states[state] += value
 
     # Output
     for state in STATES:
         print('{}.value {}'.format(state, states[state]))
 
 
+def fix_dbus():
+    """Fix DBus address for user service."""
+    if not USER:
+        return
+    euid = '/{}/'.format(os.geteuid())
+    if euid in os.environ.get('DBUS_SESSION_BUS_ADDRESS', ''):
+        return
+    os.putenv('DBUS_SESSION_BUS_ADDRESS',
+              'unix:path=/run/user{}bus'.format(euid))
+
+
 if __name__ == '__main__':
+    fix_dbus()
     if len(sys.argv) > 1 and sys.argv[1] == 'autoconf':
         print('yes' if os.path.exists('/run/systemd/system') else
               'no (systemd is not running)')