Monitoring using Munin

"Munin" can be used to monitor the activity of renderd and mod_tile on a server. Munin is available on a number of platforms; these instructions were tested on Ubuntu Linux 22.04 in June 2022 and Ubuntu Linux 24.04 in April 2024.

First, install the necessary software:

sudo apt install munin-node munin libcgi-fast-perl libapache2-mod-fcgid

If you look at /etc/apache2/conf-available you should see that munin.conf is a symbolic link to ../../munin/apache24.conf, which is /etc/munin/apache24.conf.

The file /etc/munin/apache24.conf is Apache's munin configuration file. In that file, if you want munin to be accessed globally rather than just locally change both instances of Require local to Require all granted.

Next edit /etc/munin/munin.conf. Uncomment these lines:

dbdir /var/lib/munin
htmldir /var/cache/munin/www
logdir /var/log/munin
rundir /var/run/munin

Restart munin and apache:

sudo /etc/init.d/munin-node restart
sudo /etc/init.d/apache2 restart

Browse to http://your.server.ip.address/munin. You should see a page showing apache, disk, munin, etc.

To add the plugins from mod_tile and renderd to munin:

sudo ln -s /usr/share/munin/plugins/mod_tile* /etc/munin/plugins/
sudo ln -s /usr/share/munin/plugins/renderd* /etc/munin/plugins/

There should be 4 mod_tile plugins and 5 renderd ones. Run munin's cron job manually once:

sudo -u munin munin-cron

Restart munin and apache again:

sudo /etc/init.d/munin-node restart
sudo /etc/init.d/apache2 restart

After a short delay, refreshing http://your.server.ip.address/munin/ should now show entries for mod_tile and renderd.

Munin updates its graphs every 5 minutes, as configured by the cron file /etc/cron.d/munin.