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

Creating a deployment

The Kubernetes deployment provides updates for ReplicaSets, which ensures that a specified amount of pods (replicas) are running all the time:

Figure 4.2 – Deployment with three pods

The preceding diagram shows a deployment with three pods; the ReplicaSet will try to keep three pods running all the time. Of course, if there are no free resources in the Kubernetes cluster, the running pod replicas might not match the required replica count.

There are a few ways to create a Kubernetes deployment – let's explore them. The easiest way is using $ kubectl create deployment.

Let's create an nginx deployment:

$ kubectl create deployment
deployment.apps/nginx created

Let's check the created nginx deployment:

$ kubectl get deployment
nginx   1/1     1 ...