Cluster life cycle

There are a few more key items that we should cover so that you're armed with full knowledge about the items that can help you with creating highly available Kubernetes clusters. Let's discuss how you can use admission controllers, workloads, and custom resource definitions to extend your cluster.

Admission controllers

Admission controllers are Kubernetes code that allows you to intercept a call to the Kubernetes API server after it has been authenticated and authorized. There are standard admission controllers that are included with the core Kubernetes system, and people also write their own. There are two controllers that are more important than the rest:

• TheMutatingAdmissionWebhook is responsible for calling Webhooks that mutate, in serial, a given request. This controller only runs during the mutating phase of cluster operating. You can use a controller like this in order to build business logic into your cluster to customize admission logic with operations such as CREATE...