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

Working with other required resources

Besides the CRD, our Operator will be responsible for managing a number of other cluster resources as well. Right now, this is the nginx Deployment that will be created as our Operand, as well as a ServiceAccount, Role, and RoleBinding for the Operator. What we need to understand is how the Operator will know the definition of those resources.

Somewhere, the resources need to be written as Kubernetes cluster objects. Just as you would create a Deployment by hand (for example, with kubectl create -f), the definitions of necessary resources can be packaged with the Operator code in a couple of different ways. This can be done easily with templates if you are creating your Operator with Helm or Ansible, but for Operators written in Go, we need to consider our options.

One way to package these resources so that the Operator can create them is by defining them directly in the Operator's code. All Kubernetes objects are based on corresponding...