Book Image

The Kubernetes Book

By : Nigel Poulton, Pushkar Joglekar
Book Image

The Kubernetes Book

By: Nigel Poulton, Pushkar Joglekar

Overview of this book

Kubernetes is the leading orchestrator of cloud-native apps. With knowledge of how to work with Kubernetes, you can easily deploy and manage applications on the cloud or in your on-premises data center. The book begins by introducing you to Kubernetes and showing you how to install it. You’ll learn how to use Kubernetes Services and bring stable and reliable networking to apps that are deployed on Kubernetes. You'll delve deep into the powerful storage subsystem of Kubernetes and learn how to leverage the variety of external storage backends in your applications. As the book progresses, it shows you how to use features such as DaemonSets, Helm, and RBAC to enhance your Kubernetes applications. You'll explore the six categories of identifying vulnerabilities and look at a few ways to prevent and mitigate them. You'll also look at ways to secure the software delivery pipeline by discussing some image-related best practices. The book ends by sharing with you some resources that’ll help take your Kubernetes knowledge to the next level. By the end of the book, you’ll have the confidence and skills to leverage all the features of Kubernetes to develop scalable applications.
Table of Contents (23 chapters)
Free Chapter
1
Chapter 1
3
Chapter 2
5
Chapter 3
7
Chapter 4
9
Chapter 5
11
Chapter 6
13
Chapter 7
15
Chapter 8
17
Chapter 9
19
Chapter 10
21
Chapter 11

Summary

In this chapter, we learned that the atomic unit of deployment in the Kubernetes world is the Pod. Each Pod consists of one or more containers and gets deployed to a single node in the cluster. The deployment operation is an all-or-nothing atomic transaction.

Pods are deployed declaratively using a YAML manifest file, and it's normal to deploy them via higher-level controllers such as Deployments. We use the kubectl command to POST the manifest to the API server. It gets stored in the cluster store and converted into a PodSpec that gets scheduled to a healthy cluster node with enough available resources.

The process on the worker node that accepts the PodSpec is the kubelet. This is the main Kubernetes agent running on every node in the cluster. It takes the PodSpec and is responsible for pulling all images and starting all containers in the Pod.

If a singleton Pod fails, it is not automatically rescheduled. Because of this, we usually deploy Pods via higher-level...