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

Draining nodes

You might want to remove/evict all pods from a node that is going to be deleted, upgraded, or rebooted, for example. There is a command, drain, for that. Its output is quite long, so only some of the output will be shown:

$ kubectl drain –help

We get the following output from the preceding command:

Figure 3.10 – Partial kubectl drain – help output

As you can see from the output, there are a few flags you need to pass to properly drain the node: --ignore-daemonsets and –force.


A DaemonSet ensures that all specified Kubernetes nodes run a copy of the same pod specified in the DaemonSet. A DaemonSet cannot be deleted from the Kubernetes node, so the --ignore-daemonsets flag must be used to force draining the node.

Let's drain the gke-kubectl-lab-default-pool-b3c7050d-8jhj node using the following command:

$ kubectl drain gke-kubectl-lab-default-pool-b3c7050d-8jhj --ignore-daemonsets –...