Book Image

The Kubernetes Operator Framework Book

By : Michael Dame
1 (1)
Book Image

The Kubernetes Operator Framework Book

1 (1)
By: Michael Dame

Overview of this book

From incomplete collections of knowledge and varying design approaches to technical knowledge barriers, Kubernetes users face various challenges when developing their own operators. Knowing how to write, deploy, and pack operators makes cluster management automation much easier – and that's what this book is here to teach you. Beginning with operators and Operator Framework fundamentals, the book delves into how the different components of Operator Framework (such as the Operator SDK, Operator Lifecycle Manager, and OperatorHub.io) are used to build operators. You’ll learn how to write a basic operator, interact with a Kubernetes cluster in code, and distribute that operator to users. As you advance, you’ll be able to develop a sample operator in the Go programming language using Operator SDK tools before running it locally with Operator Lifecycle Manager, and also learn how to package an operator bundle for distribution. The book covers best practices as well as sample applications and case studies based on real-world operators to help you implement the concepts you’ve learned. By the end of this Kubernetes book, you’ll be able to build and add application-specific operational logic to a Kubernetes cluster, making it easier to automate complex applications and augment the platform.
Table of Contents (16 chapters)
1
Part 1: Essentials of Operators and the Operator Framework
4
Part 2: Designing and Developing an Operator
9
Part 3: Deploying and Distributing Operators for Public Use

Operator design

The Prometheus Operator is designed to alleviate the issues mentioned earlier in regard to the complexity involved with running an instance of Prometheus in a Kubernetes cluster. It does so by abstracting the various configuration options that are available for Prometheus into CustomResourceDefinitions (CRDs), which are reconciled by the Operator's controllers to maintain that the cluster's Prometheus installation is consistent with the desired state, whatever that might be (and however it might change).

Of course, in contrast to the example nginx Operator from earlier tutorials, the Prometheus Operator manages a far more complex application with many more possible states that it must be able to reconcile. But the general approach is still the same, so we can evaluate this Operator through the lens of the same development steps that have been shown throughout this book.

CRDs and APIs

As discussed many times already, CRDs are the main objects upon...