Modern clusters running on cloud infrastructure are easy to scale up and down on demand using tools such as Puppet. When new hosts are added in and older hosts are removed from the cluster, it becomes increasingly difficult and impractical to access the cluster services directly on the hosts. A common way to deal with this issue is to add a load balancer or a proxy host in front of services that provides a single point of entry for the user to access the variety of services behind it.

In this chapter you will learn how to make the cluster more resilient and easier to use by adding a load balancer in front of the cluster. The load balancer is going to be built on the Apache web server module that we have already used on the web server and the monitoring server. We will create a new Puppet module for load balancer that interacts with the Apache module by passing class parameters which is a common way to change the behavior of a Puppet class.

This chapter...