systemd_status: reformat docstring to perlpod format

plugins/systemd/systemd_status

@@ -1,14 +1,40 @@
-#!/usr/bin/python3 -tt
-# -*- coding: utf-8 -*-
+#!/usr/bin/env python3
 # pylint: disable=invalid-name
 # pylint: enable=invalid-name
 
 """Munin plugin to monitor systemd service status.
-Copyright 2018, Kim B. Heino, b@bbbs.net, Foobar Oy
-License GPLv2+
 
-#%# capabilities=autoconf
+=head1 NAME
+
+systemd_status - monitor systemd service status, including normal services,
+mounts, hotplugs and socket activations
+
+=head1 APPLICABLE SYSTEMS
+
+Linux systems with systemd installed.
+
+=head1 CONFIGURATION
+
+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.
+
+=head1 AUTHOR
+
+Kim B. Heino <b@bbbs.net>
+
+=head1 LICENSE
+
+GPLv2
+
+=head1 MAGIC MARKERS
+
  #%# family=auto
+ #%# capabilities=autoconf
+
+=cut
+
 """
 
 import os
@@ -49,26 +75,26 @@ def fetch():
     """Print runtime values."""
     # Get data
     try:
-        output = subprocess.check_output([
-            '/bin/systemctl',
-            'list-units'])  # deb9/py3.5 doesn't have encoding parameter
+        # deb9/py3.5 doesn't have encoding parameter in subprocess
+        output = subprocess.check_output(['/bin/systemctl', 'list-units'])
     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():
-        line = line.decode('utf-8').split()
-        if len(line) < 4:
+        token = line.split()
+        if len(token) < 4:
             continue
-        if len(line[0]) < 3:  # Skip failed-bullet
-            line = line[1:]
-        if line[0].endswith('.scope'):  # Ignore scopes
-            continue
-        if re.match(r'user.*@\d+\.service', line[0]):
-            continue
-        if line[3] in states:
-            states[line[3]] = states[line[3]] + 1
+        if len(token[0]) < 3:  # Skip failed-bullet
+            token = token[1:]
+        if token[0].endswith('.scope'):
+            continue  # Ignore scopes
+        if re.match(r'user.*@\d+\.service', token[0]):
+            continue  # These fail randomly in older systemd
+        if token[3] in states:
+            states[token[3]] = states[token[3]] + 1
 
     # Output
     for state in STATES: