Preface

Before plunging into how Kubernetes works, this book introduces you to the world of container orchestration and describes the recent changes in application development. It helps you understand the problems that Kubernetes solves and shows how to use Kubernetes resources to deploy applications. You also learn to apply the security model of Kubernetes clusters. The book also describes how services running in Kubernetes can leverage the platform's security features. You learn to troubleshoot Kubernetes clusters and debug Kubernetes applications. You also learn to analyze the networking model and its alternatives in Kubernetes, and apply best practices in Kubernetes with design patterns. By the time you are done reading the book, you will know all about using the power of Kubernetes for managing your containers.

After completing this book, you will be able to:

• Understand and classify software designs patterns per the cloud-native paradigm
• Apply best practices in Kubernetes with design patterns
• Access Kubernetes API programmatically using client libraries
• Extend Kubernetes with custom resources and controllers
• Integrate into access control mechanisms and interact resource lifecycle in Kubernetes
• Develop and run custom schedulers in Kubernetes

Who This Book Is For

If you are interested in configuring and troubleshooting Kubernetes clusters and developing microservices-based applications on Kubernetes clusters, then this is a very useful book for you. DevOps engineers with basic knowledge of Docker will find this book useful.

What This Book Covers

Chapter 1, Kubernetes Design Patterns, will help you to understand Kubernetes patterns which would be presented with the examples from Kubernetes itself and external applications.

Chapter 2, Kubernetes Client Libraries, will help you to cover accessing Kubernetes API with raw HTTP queries to complex libraries with both in-cluster and out-cluster examples.

Chapter 3, Kubernetes Extensions, will present extension capabilities of Kubernetes with custom resource definitions, custom controllers, dynamic admission controllers, and custom schedulers.

To Get the Most out of This Book

We assume that you are comfortable with command-line tools and computer programming concepts and languages. The minimum hardware requirements are: Intel Core i7 or equivalent, 8 GB RAM, 35 GB hard disk, and a stable internet connection. You'll also need the following software installed in advance:

• Access to a Kubernetes cluster with the version equal to or higher than 1.10
  Local Kubernetes solutions such as minikube or clusters living in cloud providers: https://github.com/kubernetes/minikube
• Kubernetes command line tool kubectl is required for accessing Kubernetes from terminal:
  https://kubernetes.io/docs/tasks/tools/install-kubectl/
• Docker client and server with the minimum version of 18.03 are required for building and testing the client libraries:
  https://www.docker.com/get-started
• Installing Python and Go are not required, however recommended for playing around with the client libraries locally:
  • https://www.python.org/downloads/
  • https://golang.org/

Download the Example Code Files

You can download the example code files for this book from your account at www.packt.com. If you purchased this book elsewhere, you can visit www.packt.com/support and register to have the files emailed directly to you.

You can download the code files by following these steps:

1. Log in or register at www.packt.com.
2. Select the SUPPORT tab.
3. Click on Code Downloads & Errata.
4. Enter the name of the book in the Search box and follow the onscreen instructions.

Once the file is downloaded, please make sure that you unzip or extract the folder using the latest version of:

• WinRAR/7-Zip for Windows
• Zipeg/iZip/UnRarX for Mac
• 7-Zip/PeaZip for Linux

The code bundle for the book is also hosted on GitHub at https://github.com/TrainingByPackt/Kubernetes-Design-Patterns-and-Extensions. In case there's an update to the code, it will be updated on the existing GitHub repository.

We also have other code bundles from our rich catalog of books and videos available at https://github.com/PacktPublishing/. Check them out!

Conventions Used

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "With this method, kubectl securely connects to the API server with its own credentials and creates a proxy for the applications on the local system."

A block of code is set as follows:

{
  "apiVersion":"v1",
  "kind":"Namespace",
  "metadata":{
    "name":"packt-client”
  }
}

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

curl -X POST http://localhost:8080/api/v1/namespaces/  \
--header "Content-Type:application/json" \

Activity: These are scenario-based activities that will let you practically apply what you've learned over the course of a complete section. They are typically in the context of a real-world problem or situation.

Warnings or important notes appear like this.

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All the solutions to the activities are present in the Appendix section.