Munin and Apache: Can’t locate object method

If you’re using Munin to track statistics on your server and you’re trying to use any of the Apache plugins, you might have some trouble getting it working. If Munin won’t display any statistics on Apache, and the munin-node.log logfile is filled with lines like these:

Can't locate object method "new" via package "LWP::UserAgent"
at /etc/munin/plugins/apache_processes line 152.
2009/07/08-17:00:02 Plugin "apache_processes" exited with status 512. ----
Can't locate object method "new" via package "LWP::UserAgent"
at /etc/munin/plugins/apache_accesses line 130.
2009/07/08-17:00:03 Plugin "apache_accesses" exited with status 512. ----
Can't locate object method "new" via package "LWP::UserAgent"
at /etc/munin/plugins/apache_volume line 130.
2009/07/08-17:00:03 Plugin "apache_volume" exited with status 512. ----

then the solution is to install the package libwww-perl which includes the required LWP:UserAgent package.

Make sure to restart munin-node afterwards:

$ /etc/init.d/munin-node restart