Describing the problem

Many software projects can be defined with a user story in the following format: As a [user] I want to [action], so that [reason]. We'll also do that here, as follows:

As a cluster administrator, I want to use an Operator to manage my nginx application so that its health and monitoring are automatically managed for me.

For our use case (designing an Operator), we don't care about the specific application right now. For that reason, our application is just going to be a basic nginx sample Pod. We will assume that this represents any single-Pod application with basic input/output (I/O) needs. While this may seem too abstract, the focus will be on building an Operator around the application.

The first thing we have identified from this user story is that we will be building the Operator for cluster administrators. From the previous chapter, we know this means that the Operator's users will have a better understanding of the cluster architecture...