I've setup munin to monitor a bunch of hosts, including 4 web servers where I wanted to include apache monitoring. I got all the graphs working, except for apache monitoring on 3 of the 4 web servers.
I followed these instructions to set this up:
On the one web server that I got the apache graphs to work correctly and show up in munin, I had SELinux disabled. The other 3 where the graphs weren't working, I had SELinux turned on. So I tried turning it off, and restarting apache and munin-node on the 3 web servers. And I waited around for a while after exercising applications that are running on those servers.
The only thing I found in the logs relating to munin was this message:
[root@ops1:~] #grep munin /var/log/messages
Oct 25 11:25:13 ops1 yum: Installed: munin-node-2.0.25-2.el7.noarch
Oct 25 11:39:02 ops1 systemd: PID file /var/run/munin/munin-node.pid not readable (yet?) after start.
Which doesn't relate to the problem of having only the apache monitoring not work, with the graphs being empty.
How can I troubleshoot this and get the apache graphs working?