[plugin/user/cronjobs] added plugin to monitor cronjobs

Graphs the number of cronjobs active at a certain moment, per user

plugins/user/cronjobs

@@ -0,0 +1,165 @@
+#!/usr/bin/env python3
+# -*- python -*-
+"""
+=head1 NAME
+
+Plugin to monitor the number of cronjobs running per user, gathering data from
+syslog.
+
+=head1 INSTALLATION
+
+Usage: Place in /etc/munin/plugins/ (or link it there using ln -s)
+
+=head1 CONFIGURATION
+
+Add this to your /etc/munin/plugin-conf.d/munin-node:
+
+=over 2
+
+      [cronjobs]
+      user root
+      env.syslog_path /var/log/syslog # default value
+      env.cron_ident_regex crond? # for finding cron entries in the syslog,
+                                    case-insensitive (default value)
+
+=back
+
+The plugin needs to run as root in order to read from syslog.
+
+=head1 HISTORY
+
+2019-09-09: v 1.0 pcy <pcy.ulyssis.org>: created
+
+=head1 USAGE
+
+Parameters understood:
+
+  config   (required)
+  autoconf (optional - used by munin-config)
+
+=head1 MAGIC MARKERS
+
+#%# family=auto
+#%# capabilities=autoconf
+"""
+
+
+from datetime import datetime, timedelta, timezone
+import os
+import re
+import shutil
+import socket
+import sys
+import struct
+import time
+
+
+syslog_path = os.getenv('syslog_path', '/var/log/syslog')
+cron_ident_regex = os.getenv('cron_ident_regex', 'crond?')
+
+# expected format:
+# <date> <hostname> CRON[<pid>]: (<user>) CMD ...
+# example:
+# Aug 16 22:00:01 zap CRON[23060]: (root) CMD (/usr/local/bin/dnsconfig -s)
+cron_syslog_regex = re.compile('^.* %s %s\[[0-9]*\]: \((.*?)\)'  # noqa: W605
+                               % (socket.gethostname(), cron_ident_regex),
+                               re.I)
+
+STATEFILE = os.getenv('MUNIN_STATEFILE')
+
+
+def loadstate():
+    if not os.path.isfile(STATEFILE):
+        return None
+
+    with open(STATEFILE, 'rb') as f:
+        tstamp = struct.unpack('d', f.read())[0]
+        return datetime.fromtimestamp(tstamp, tz=timezone.utc)
+
+
+def savestate(state):
+    with open(STATEFILE, 'wb') as f:
+        f.write(struct.pack('d', state.timestamp()))
+
+
+def extrcronuser(line: str):
+    t = cron_syslog_regex.search(line)
+    if t is None:
+        return None
+    gr = t.groups()
+    return gr[0] if len(gr) == 1 else None
+
+
+def getcronlines():
+    with open(syslog_path, 'r') as f:
+        for x in f.readlines():
+            user = extrcronuser(x)
+            if user is not None:
+                yield (x, user)
+
+
+def getcronusers(lines):
+    return set(x[1] for x in lines)
+
+
+def autoconf():
+    if shutil.which('crontab') is None:
+        print("no (need cron installed)")
+    elif not os.access(syslog_path, os.R_OK):
+        print("no (cannot access syslog file '%s')" % syslog_path)
+    else:
+        print("yes")
+
+
+def config():
+    usernames = getcronusers(getcronlines())
+    print("""\
+graph_title Cron jobs per user
+graph_vlabel jobs
+graph_category processes""")
+    for n in usernames:
+        print(n + ".label " + n)
+        print(n + ".info jobs of user " + n)
+
+
+def fetch():
+    STATE = loadstate()
+    # why is there no stdlib function for this?!
+    localtz = timezone(timedelta(seconds=time.localtime().tm_gmtoff))
+    now = datetime.now()
+    now_withtz = datetime.now(tz=localtz)
+    yearsfx = ' ' + str(now.year)
+    pyearsfx = ' ' + str(now.year - 1)
+    cronlines = list(getcronlines())
+    allnames = getcronusers(cronlines)
+    counts = {}
+
+    hostname = socket.gethostname()
+    for ln, name in cronlines:
+        datestr = ln[:ln.index(hostname)].strip()
+        logdate = datetime.strptime(datestr + yearsfx, "%b %d %H:%M:%S %Y")
+        if logdate > now:
+            logdate = datetime.strptime(datestr + pyearsfx, "%b %d %H:%M:%S %Y")
+        # add timezone info (ugly hack), as strptime doesn't want to do this
+        logdate = now_withtz + (logdate - now)
+        if STATE is None or logdate > STATE:
+            counts[name] = (counts[name] + 1) if name in counts else 1
+
+    for n in allnames:
+        if n in counts:
+            print("%s.value %d" % (n, counts[n]))
+        else:
+            print("%s.value 0" % n)
+
+    savestate(now_withtz)
+
+
+if len(sys.argv) >= 2:
+    if sys.argv[1] == 'autoconf':
+        autoconf()
+    elif sys.argv[1] == 'config':
+        config()
+    else:
+        fetch()
+else:
+    fetch()