In the last few posts, we have looked in detail at the various parts of the machinery behind Kubernetes controllers - informers, queues, stores and so forth. In this final post, we will wrap up a bit and see how all this comes together in the Kubernetes sample controller. The flow of control The two … Continue reading Understanding Kubernetes controllers part IV – putting it all together
After understanding how an informer can be used to implement a custom controller, we will now learn more about the inner working of an informer. We have seen that essentially, informers use the Kubernetes API to learn about changes in the state of a Kubernetes cluster and use that information to maintain a cache (the … Continue reading Understanding Kubernetes controllers part III – informers
In the last post, we have seen that our sample controller uses Listers to retrieve the current state of Kubernetes resources. In this post, we will take a closer look at how these Listers work. Essentially, we have already seen how to use the Kubernetes Go client to retrieve informations on Kubernetes resources, so we … Continue reading Understanding Kubernetes controllers part II – object stores and indexers
In previous posts in my series on Kubernetes, we have stumbled across the concept of a controller. Essentially, a controller is a daemon that monitors the to-be state of components of a Kubernetes cluster against the as-is state and takes action to reach the to-be state. A classical example is the Replica set controller which … Continue reading Understanding Kubernetes controllers part I – queues and the core controller loop
The Kubernetes API is structured around resources. Typical resources that we have seen so far are pods, nodes, containers, ingress rules and so forth. These resources are built into Kubernetes and can be addresses using the kubectl command line tool, the API or the Go client. However, Kubernetes is designed to be extendable - and … Continue reading Extending Kubernetes with custom resources and custom controllers
So far we have described how a client program utilizes the Kubernetes library to talk to a Kubernetes API server. In this post, we will actually look into the Kubernetes client code and try to understand how it works under the hood. When we work with the Kubernetes API and try to understand the client … Continue reading Learning Go with Kubernetes IV – life of a request
In the last post, we have seen how structures, methods and interfaces in Go are used by the Kubernetes client API to model object oriented behavior. Today, we will continue our walk through to our first example program. Arrays and slices Recall that in the last point, we got to the point that we were … Continue reading Learning Go with Kubernetes III – slices and Kubernetes resources
