How to Monitor Nagios itself for free

So, you run your own monitoring? Nice!

But how do you monitor your monitoring? Who will alert you when your monitoring service is down?

We wanted to encourage all Nagios and Icinga administrators out there to start monitoring their own monitoring. So we did something unprecedented.

We made Server Density free

That’s right. If you are looking for a tool to monitor your monitoring, then look no further. We are offering a free Server Density account, valid for one server and one website.

But we didn’t stop there.

To help you monitor your monitoring, we even created Server Density plugins for Icinga and Nagios.

This article outlines some key Nagios / Icinga metrics you need to monitor, followed by step by step instructions for doing this with Server Density.

Nagios performance metrics

Let’s take a look at some Nagios performance metrics:

Nagios server alerts

It’s also a good idea to configure standard system metrics:

In addition to the above, you should also collect metrics for disk IO and network bandwidth. If you use MySQL or PostgreSQL IDO, then monitoring those databases is highly recommended too.

Monitoring Nagios itself with Server Density

Here is what you need to do:

1. Register for your free Server Density account (limited to 1 server + 1 website)
2. Enter your credit card information in Preferences > Billing. This is to verify your account and you will not be charged.
3. Install the agent on your monitoring server:
   

   $ curl -Lk https://www.serverdensity.com/downloads/agent-install.sh > install.sh
   $ chmod +x install.sh
   $ sudo ./install.sh -a https://example.serverdensity.io -t your_licensekey

4. Configure your plugin path:
   

   $ sudo sed -i 's/plugin_directory: $/plugin_directory: \/usr\/local\/share\/sd-plugins\//g' /etc/sd-agent/config.cfg

5. Add the sd-agent user to your Nagios group (same for Icinga):
   

   $ sudo adduser sd-agent nagios

6. Install the plugin:
   For Nagios3/Icinga1:
   

   $ cd /usr/local/share/sd-plugins/ && sudo wget https://raw.githubusercontent.com/bencer/sd-agent-plugins/master/Nagios/Nagios.py
   $ sudo vi /etc/sd-agent/plugins.cfg
   [Nagios]
   cmd_path = /usr/local/nagios/bin/nagiostats

   
   And restart the agent to apply changes:
   

   $ sudo service sd-agent restart

   
   For Icinga2:
   

   $ cd /usr/local/share/sd-plugins/ && sudo wget https://raw.githubusercontent.com/bencer/sd-agent-plugins/master/Icinga2/Icinga.py

   
   Now we need to configure Icinga2 API (if not configured yet):
   

   $ cd - ; sudo -s
   # icinga2 api setup
   information/cli: Generating new CA.
   [...]
   Done.
   Now restart your Icinga 2 daemon to finish the installation.
   # service icinga2 restart

   
   Check your auto-generated username and password and configure the credentials for the plugin:
   

   $ sudo cat /etc/icinga2/conf.d/api-users.conf
   $ sudo vi /etc/sd-agent/plugins.cfg
   [Icinga]
   api_user = root
   api_passwd = your_password
   # you will need FQDN to match the cert CN
   api_stats_url = https://your_fqdn:5665/v1/status
   # Icinga PKI CA cert
   icinga_ca_crt = /etc/icinga2/pki/ca.crt

   
   And restart the agent to apply changes:
   

   $ sudo service sd-agent restart

7. Login to Server Density and start playing with the alerts by creating similar dashboards.

Summary

If you run your own monitoring servers then make sure that “monitoring your monitoring” is high on your DevOps checklist.

Grab your free Server Density account, play around with the alerts and dashboards and let us know what you think.

Do you monitor any other performance metrics on your monitoring service? Make sure you add those in the comments.

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