Nagios is a very powerful platform because it is easy to extend. The previous chapters talked about check command plugins and how they can be used to check any host or service that your company might be using. Another great feature that Nagios offers is the ability for third-party software or other Nagios instances to report information on the status of services or hosts. This way, Nagios does not need to schedule and run checks by itself, but other applications can report information as it is available to them.

This means that your applications can send problem reports directly to Nagios, instead of just logging them. In this way, your applications can benefit from powerful notification systems as well as dependency tracking. This mechanism can also be used to receive failure notifications from other services or machines — for example, SNMP (Simple Network Management Protocol) traps. This is described in more detail in Chapter 9.

Nagios also offers a tool...