Summary

In this chapter, you learned about custom controllers. As per the Kubernetes glossary, a controller implements a control loop to watch the state of the cluster through the API server and makes changes in an attempt to move the current state toward the desired state.

Controllers can not only watch and manage user-defined CRs, but they can also act on resources such as Deployments or services, which are typically part of the Kubernetes controller manager. Controllers provide a way to write your own code to suit your business needs.

CRDs are the central mechanism used in the Kubernetes system to extend its capability. CRDs provide a native way to implement custom logic for the Kubernetes API server that satisfies your business requirements.

You have learned about how CRDs and controllers help provide an extension mechanism for the Kubernetes platform. You have also seen the process through which you can configure and deploy custom controllers on the Kubernetes platform...