In this chapter, we learned how to create a Nagios module that includes subclasses. Subclasses provide two streams of deployment logic. We used nagios::server class to deploy the Nagios Server, and we installed Nagios Client on the web server by including class nagios::client in the webapp module. We also had a look at how to configure Nagios hosts and services with Puppet's built-in resource types, nagios_host and nagios_service.

In the next chapter, we will continue to expand the cluster by adding a load balancer node in front of the web and monitoring servers. The load balancer will provide a single point of access to web interfaces of both servers.