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

Assigning an application to a specific node (node affinity)

There are some use cases where Kubernetes clusters have different node pools with different specs, such as the following:

  • Stateful applications
  • Backend applications
  • Frontend applications

Let's reschedule the nginx deployment to a dedicated node pool:

  1. To get the nodes list, run the following command:
    $ kubectl get nodes

    The preceding command gives the following output:

    Figure 5.3 – Node pools list

  2. Next, let's check a node under the gke-kubectl-lab-we-app-pool name. Run the following command:
    $ kubectl describe node gke-kubectl-lab-we-app-pool-1302ab74-pg34

    The output of the preceding command is as shown in the following screenshot:

    Figure 5.4 – Node labels

  3. There, we have a node-pool=web-app label, which is the same for all nodes of the gke-kubectl-lab-we-app-pool pool.
  4. Let's update the deployment.yaml file with the nodeAffinity rule, so the nginx application...