We’re currently expanding our munin reporting cluster at Derdubor, but after installing munin-node on one of our servers we never got any graphs. The only section available on the munin server was “Other”, and that didn’t contain any information at all (which indicates that you’re not getting any response from the server).
The first step I make when trying to debug a munin connection is to telnet into the munin port, as this confirms that the two servers are able to talk to each other and that the munin daemon listens to the correct interface and port.
# telnet localhost 4949 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. Connection closed by foreign host. #
The connection was established, but then munin closed the connection as soon as it was created. This usually means one thing: the host you’re connecting from isn’t added to the cidr_allow list or the allow list, or in the denied hosts list. This time it meant neither, the host was added and we didn’t have any denied hosts list.
The next step was to take a look at the munin-node.log in /var/log/munin (at least under under debian).
The last message was:
User "ejabberd" in configuration file "/etc/munin/plugin-conf.d/munin-node" nonexistant. Skipping plugin. at /usr/sbin/munin-node line 615,
Something wicked happened while reading "/etc/munin/plugins/munin-node". Check the previous log lines for spesifics. at /usr/sbin/munin-node line 261,
We don’t have ejabberd installed, but the ejabberd config reference was apparently added to the configuration file in /etc/munin/plugin-conf.d/munin-node. This made our version of munin-node barf, as the user it reference wasn’t available.
Next step was to remove the section from the file and restarting munin-node:
/etc/init.d/munin-node restart
After restarting munin, I did the telnet check again:
# telnet localhost 4949 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. # munin node at example.com . fetch load load.value 0.02 . quit Connection closed by foreign host. #
Wait 10 – 15 minutes and you should start seeing graphs again – if this actually were your problem. Probably not (and then you should probably read Debuggning Munin Plugins and other documentation on the Wiki). But if it were, you’ll be happy happy joy joy now.