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

Designing an API and a CRD

As we covered in Chapter 1, Introducing the Operator Framework, and Chapter 2, Understanding How Operators Interact with Kubernetes, the use of a CRD is a defining characteristic of Operators to create an object for users to interact with. This object creates an interface for controlling the Operator. In this way, the Custom Resource (CR) object is a window into the Operator's main functions.

As with any good window, the Operator's CRD must be built well. It must be clear enough to expose the details of the Operator while being secure enough to keep out harsh weather and burglars, and as with a window, the CRD's design should follow local building codes to ensure that it is built up to the expected standards of the environment. In our case, those building codes are the Kubernetes API conventions.

Following the Kubernetes API design conventions

Even though a CRD is a custom object that can be created by anyone, there are still best...