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)
1
Section 1: Getting Started with kubectl
3
Section 2: Kubernetes Cluster and Node Management
6
Section 3: Application Management
10
Section 4: Extending kubectl

Using Helm's template command

With Helm's helm template command, you can check the output of the chart in fully rendered Kubernetes resource templates. This is a very handy command to check the templates' outputs, especially when you are developing a new chart, making changes to the chart, debugging, and so on.

So, let's check it out by running the following command:

$ helm template postgresql center/bitnami/postgresql --version=9.3.2 -f password-values.yaml

The preceding command will print all templates on the screen. Of course, you can pipe it out to the file as well.

As the output is very long, we aren't going to print all of it, but only parts of the Kubernetes manifest:

---
# Source: postgresql/templates/secrets.yaml
apiVersion: v1
kind: Secret
metadata:
  name: postgresql
...
---
# Source: postgresql/templates/svc-headless.yaml
apiVersion: v1
kind: Service
metadata:
  name: postgresql-headless
...
---
# Source: postgresql...