Today I went to add a new server to my monitoring setup and experienced an odd issue. I of course first installed the munin-node to the host and updated the munin.conf file on the monitoring server. Since the munin script runs every 5 minutes it generally takes a while to see the results of the new host in the graphs. The host showed up in the list of monitored servers…just no list of services monitored.
After some time I still wasn’t seeing any results. It took me some time to figure this one one. I looked up all sorts of help on Google and monitored the various munin and linux log files…nothing which helped. I finally started to diagnose the issue by running the munin scripts manually.
It took forever but I finally figured out that the host name on the new server was the cause of the issue. Apparently the hostname of the server needs to match exactly (including case) what the hostname is in the munin.conf file. When I read this in the munin-node.conf file:
# Set this if the client doesn't report the correct hostname when
# telnetting to localhost, port 4949
it occurred to me to telnet into the host to see if the hostname matched. I’d telneted in already to ensure there wasn’t a firewall issue, but I didn’t think about the host name.
So if your munin graphs don’t work be sure to either use the exact same hostname in the munin-conf file or set the host_name in the munin-node.conf file to match that which you used in the munin.conf on the monitoring server.
** normally at this point I give credit to the website that helped me figure this out, but this time I did it all on my own.