Defining commands

The commands that you may use for a given service need to be defined as well. The commands are defined within /etc/nagios-plugins/config, which is also included by /etc/nagios3/nagios.cfg.

This is a useful place to look if you want to see how an existing command is defined, or if you want to define your own custom command.

How to do it…

Let's create a custom command that uses an existing plugin to monitor a new service. Plex media servers are configured by default to use a web server configured on port 32400. So let's define a check_plex service that uses check_http on port 32400.

To do this, we're going to create /etc/nagios-plugins/config/plex.cfg:

define command{
        command_name    check_plex
        command_line    /usr/lib/nagios/plugins/check_http -H '$HOSTADDRESS$' -I '$HOSTADDRESS$' -p 32400 '$ARG1$'
        }

How it works…

Command definitions are simple. You provide a command name and then the command you're going to execute on the local box in order to collect data...