Well, did you try the basics of finding problems with munin plugins, i.e. run them manually on the console with ‘munin-run’?
The mod_tile-plugin is a rather simple script, if it doesn’t work my best guesses would be a) you don’t have ‘wget’ installed or b) your apache-config prevents access to /mod_tile for localhost.
I’ve checked ‘munin-run df’ and it works just fine.
Then I’ve checked ‘munin-run mod_tile_response’ and it returns error:
Can’t exec “/etc/munin/plugins/mod_tile_response”: Permission denied at /usr/share/perl5/Munin/Node/Service.pm line 241
So I’ve checked file permissions of mod_tile plugins and they are all the same as other munin plugins.
What permissions we are talking about then?
I’ve ‘wget’ installed, munin webpage is working just fine and /mod_tile webpage is displaying results correctly.
Problem solved.
Soft links in directory /etc/share/munin were pointing to mod_tile munin plugins stored in /root directory.
I’ve moved plugins from /root directory to more accessible location and recreated the soft links.