Munin is a program that gives you some graphs about your system that you can visualize from a web page.
there are two parts to this, the server and the client, you can have one server and as many clients (nodes) as you may need, and so from the server you can read the infos from your nodes. in this tutorial i'll show you the most basic setup, you will be able to complicate things on your own.
on Debian all you need to do is:
apt-get install munin munin-node
these folders will be created:
In /etc/munin/munin.conf there should be:
dbdir /var/lib/munin htmldir /var/www/munin logdir /var/log/munin rundir /var/run/munin
if you want to change something, like htmldir, this is where you do that.
you can also modify (example):
[localhost.localdomain] address 127.0.0.1 use_node_name yes
[machinename.lan] address 127.0.0.1 use_node_name yes
this tells the server which nodes it needs to get infos from and there name (can help to know what you are looking at). this would be where you can add your nodes
looking at the graphs
all you need to do is point your browser to the page defined by htmldir, in this case: /var/www/munin
on Debian by default it would be http://IP/munin this could vary.
the default configuration should be good enough for now, however you can look into /etc/munin/munin-node.conf and see what's up there. if your node is not on the server itself you my want to allow access to the server, add something like this:
allow ^127\.0\.0\.1$ allow ^192\.168\.1\.11$
here we allow localhost and a computer on the lan (this should be the server that regroups all the graphs), this works for public IPs of course, if you are wondering which port to open the answer is: TCP 4949
adding a plugin is, normally, as simple as adding a link in /etc/munin/plugins/ to the plugin file that is in /usr/share/munin/plugins/, then you configure the plugin and restart munin-node
for example :
cd /etc/munin/plugins/ ln -s /usr/share/munin/plugins/df . # this one might already be activated. ./df autoconf yes /etc/init.d/munin-node restart
of course it wont always be that easy, instructions are in the plugin file itself, read that for each plugin may have different requirements and installation methods, some may require kernel modules and or software too.
some plugins are suffixed with an underscore "_", for these you should not just create a link, let's see how this works with an example:
say i'd like to use sensors, i notice /usr/share/munin/plugins/sensors_, now i use the suggest option:
fan volt temp
so for the temperature i'd do this:
cd /etc/munin/plugins/ ln -s /usr/share/munin/plugins/sensors_ sensors_temp
easy as pie, now you can go and make things complicated.. . . . :]