Book Image

kubectl: Command-Line Kubernetes in a Nutshell

By : Rimantas Mocevicius
Book Image

kubectl: Command-Line Kubernetes in a Nutshell

By: Rimantas Mocevicius

Overview of this book

The kubectl command line tool lets you control Kubernetes clusters to manage nodes in the cluster and perform all types of Kubernetes operations. This introductory guide will get you up to speed with kubectl in no time. The book is divided into four parts, touching base on the installation and providing a general overview of kubectl in the first part. The second part introduces you to managing Kubernetes clusters and working with nodes. In the third part, you’ll be taken through the different ways in which you can manage Kubernetes applications, covering how to create, update, delete, view, and debug applications. The last part of the book focuses on various Kubernetes plugins and commands. You’ll get to grips with using Kustomize and discover Helm, a Kubernetes package manager. In addition to this, you’ll explore how you can use equivalent Docker commands in kubectl. By the end of this book, you’ll have learned how to install and update an application on Kubernetes, view its logs, and inspect clusters effectively.
Table of Contents (16 chapters)
Section 1: Getting Started with kubectl
Section 2: Kubernetes Cluster and Node Management
Section 3: Application Management
Section 4: Extending kubectl

Introduction to pods

A pod is a collocated group of application containers with shared volumes.

The applications in a pod all use the same network namespace, IP address, and port space. They can find and communicate with each other using localhost. Each pod has an IP address in a flat shared networking namespace that has full communication with other physical computers and containers across the network.

Pods are the smallest deployable units that can be created, scheduled, and managed with Kubernetes. Pods also can be created individually. As pods do not have a managed life cycle, if they die, they will not be recreated. For that reason, it is recommended that you use a deployment even if you are creating a single pod.

Pods are also used in DaemonSets, StatefulSets, Jobs, and CronJobs:

Figure 4.1 – Pod with two containers

The preceding diagram shows a pod with two containers. Containers in a pod share the same Linux network namespace as well...