System monitoring with munin

Sometimes it's nice to be able to glance at a graph and see a trend such as how the server handles the Friday rush. Exactly when is the swap space being utilised? Is mysql using cached queries?

Munin goes a long way to answering these questions with easy to read graphs and charts.

The install and configuration of munin is very simple and should take no more than a couple of minutes.

We start by installing munin and some preconfigured nodes:

sudo apt-get install munin munin-node

Well, that's the install done.

To configure munin, open the config file with your favourite text editor:

sudo nano /etc/munin/munin.conf

Make a note of the htmldir. The default entry is:

htmldir /var/www/munin

The only line you would want to change at this stage is if you want to be notified of changes. Uncomment the following line and enter a relevant email address:

#contact.someuser.command mail -s "Munin notification" somejuser@fnord.comm

Well, that's the configuration done.

Restart munin:

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

To navigate the output, use an existing domain and create a 'munin' folder. As such, create a link from the htmldir you noted earlier to your domain's munin folder:

ln -s /var/www/munin/ /home/paul/public_html/mydomain.com/public/munin

My advice would be not to actually call the public folder 'munin'. Pick something else as this helps stop casual scans of known application names.

Now comes the difficult part: you have to wait a few minutes for the output to be generated...... Navigate to your 'munin' folder, e.g:

http://www.mydomain.com/munin

You will be presented with:

Clicking 'localdomain' will give a choice of variables to examine:

Select an option and after a few hours you will start to see something like this:

As that came from my test server, not a lot's happening but you get the idea.

Final thing is to password protect the 'munin' directory.

If you use Litespeed please reference the Litespeed .htpasswd protection article but it's very easy to do:

Add a new static 'context' to the Virtual Host - add '/munin/' to the url field, 'yes' to accessible and add a realm:

Apply changes and restart the server. Now you have a password protected munin install.

PickledOnion

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