When the number of your servers is increasing more than you have expected, is a good practice to have a friend that helps you track what’s happenning on those.
For this I use, among other apps, Munin. Munin is a “networked resource monitoring tool that can help analyze resource trends and […] problems” according to its site.
But this post isn’t a howto-install guide but a how to personalize and extend munin to fit your requirements, just with a custom layout and new plugins.
Layout
I don’t like the default theme of munin. There is an alternative template at http://www.doeeng.com/ and a live demo. There are detailed instructions to install and customize there so I won’t touch it here. Seems that original webpage is down so let me explain the installation process.
You can download a tarball containing the alternative template from http://mabishu.com/downloads/munin-alternative-template.tbz
For installing just move the /etc/munin/templates to /etc/munin/templates_old, extract this tarball in /etc/munin/ and verify that this creates a new template folder. Just a puntualization, for me is far better the “template-light” so you have to change the import in index.css to get it.
Plugins
Is very simple to install plugins for munin. You only have to drop it on /usr/share/munin/plugins and after that make a symbolic link from /etc/munin/plugins to it. Fortunately, on Debian systems when you install munin and munin-node there is some plugins installed. Indeed, that plugins would cover all your needs but if you need more you can install “munin-plugins-extra” and on Ubuntu Lucid you can install “munin-libvirt-plugins”
and “munin-java-plugins”.
Additionally, Munin has the MuninExchange site that is a central point when all the users send their plugins to share with all with open licences. There is a lot of plugins but I have to highligth Memcache plugin, sshd_log, and apache