Monitoring IT infrastructure using multiple Nagios instances requires a way to send information from slave servers to one or more master servers. This can be done as events that are triggered when a service or a host state changes. However, this has a huge drawback of necessitating the set-up of an event handler for each object. Another disadvantage is that the event handlers are only triggered on actual changes, and not after each test is done.

Nagios offers another way to do this, through obsessive notifications. These provide a mechanism for running commands when a host or a service status is received — regardless of whether it is a passive or active check result. The mechanism is also set up system-wide, which means that object definitions do not need to be changed in any way for Nagios to send information about their status changes.

Setting up obsessive notifications requires a couple of changes in your configuration. The first one is to define a command that...