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

Upgrading Helm releases

In the previous section, we installed PostgreSQL, so now let's try and upgrade it. We need to know how to do this because it will have to be upgraded from time to time.

For the upgrade, we are going to use the latest available PostgreSQL chart version, that is, 9.3.2.

Let's get and run the upgrade with the following command:

$ helm upgrade –i postgresql center/bitnami/postgresql --version=9.3.2 -f password-values.yaml

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

Figure 9.11 – Listing Helm releases

We ran the preceding helm upgrade command to change the postgresql chart version to 9.3.2, but we see the PostgreSQL version is still the same as it was, that is, 11.9.0, so that means the chart itself received some changes, but the application version was kept the same.

Running helm ls shows REVISION 2, which means the second release for the PostgreSQL chart.