If you want to gather statistics on a machine with a Munin server, install munin node:

aptitude -P install munin-node munin-plugins-extra

You will also need:

aptitude -P install libio-all-lwp-perl lynx

To make sure apache status works, go to /usr/share/munin/plugins and type:

./apache_processes autoconf

This will tell if your machine is configured correctly. On every machine that I install munin, it seems it has different dependencies, and if you’re missing anything, this autoconf will tell.

One of the things it will often say, is to enable extended status. Put that in /etc/apache2/mods-enabled/status.conf:

<IfModule mod_status.c>
ExtendedStatus on

Beware though, extended status makes apache slower.

You can then go to /etc/munin/plugins and symlink all apache_* from /usr/share/munin/plugins there. It may have already done that if the autoconf conditions were met when you installed them, but I’m not sure.

Then either set the allowed server IP address in /etc/munin/munin-node.conf, or do as I do and add this to that config:

Allow ^.*$

And use iptables to only allow access from a given IP to port 4949.