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

Using failure reporting

When it comes to failures, there are two things we need to worry about: failures in the Operand, and failures in the Operator itself. Sometimes, these two instances may even be related (for example, the Operand is failing in an unexpected way that the Operator does not know how to resolve). When any errors occur, it's an important job of the Operator to report those errors to the user.

When an error happens during the Operator's reconciliation loop, the Operator must decide what to do next. In implementations with the Operator SDK, the reconcile logic is able to identify when an error has occurred and attempt the loop again. If the error continues to prevent the reconciliation from succeeding, the loop can exponentially back off and wait longer between each attempt in the hope that whichever condition is causing the failure will be resolved. However, when an Operator reaches this state, the error should still be exposed to the user in some way.

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