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

Chapter 3: Designing an Operator – CRD, API, and Target Reconciliation

The lessons from the previous chapters have helped us understand the foundational basics of the Operator Framework. In Chapter 1, Introducing the Operator Framework, we covered the conceptual pillars of the Operator Framework and the purposes they serve. Then, in Chapter 2, Understanding How Operators Interact with Kubernetes, we discussed some general principles of software design in the context of Kubernetes and the Operator Framework. Together, these chapters have established a baseline understanding of Operators and their development in broad terms. Now, we will be applying this knowledge with examples and begin designing our own Operator.

We'll start by defining a simple problem that our Operator is going to solve. In this case, that will be managing a basic deployment of an application with a single Pod. Over the next few chapters, we will add functionality to this Operator with specific code...