Book Image

The Kubernetes Workshop

By : Zachary Arnold, Sahil Dua, Wei Huang, Faisal Masood, Mélony Qin, Mohammed Abu Taleb
Book Image

The Kubernetes Workshop

By: Zachary Arnold, Sahil Dua, Wei Huang, Faisal Masood, Mélony Qin, Mohammed Abu Taleb

Overview of this book

Thanks to its extensive support for managing hundreds of containers that run cloud-native applications, Kubernetes is the most popular open source container orchestration platform that makes cluster management easy. This workshop adopts a practical approach to get you acquainted with the Kubernetes environment and its applications. Starting with an introduction to the fundamentals of Kubernetes, you’ll install and set up your Kubernetes environment. You’ll understand how to write YAML files and deploy your first simple web application container using Pod. You’ll then assign human-friendly names to Pods, explore various Kubernetes entities and functions, and discover when to use them. As you work through the chapters, this Kubernetes book will show you how you can make full-scale use of Kubernetes by applying a variety of techniques for designing components and deploying clusters. You’ll also get to grips with security policies for limiting access to certain functions inside the cluster. Toward the end of the book, you’ll get a rundown of Kubernetes advanced features for building your own controller and upgrading to a Kubernetes cluster without downtime. By the end of this workshop, you’ll be able to manage containers and run cloud-based applications efficiently using Kubernetes.
Table of Contents (20 chapters)
Preface

What Is a ConfigMap?

A ConfigMap allows us to define application-related data. A ConfigMap decouples the application data from the application so that the same application can be ported across different environments. It also provides a way to inject customized data into running services from the same container image.

ConfigMaps can be created through a literal value or from a file or all the files in a directory. Note that the primary data we stored in ConfigMaps is for non-sensitive configuration, for example, config files or environment variables.

Once a ConfigMap is defined, it will be loaded to the application via an environment variable or a set of files. The application can then see the files as local files and can read from them. It is important to note that (from 1.9.6 version onward of Kubernetes), files loaded from ConfigMaps are read-only. ConfigMaps can also hold configuration data for system applications such as operators and controllers.

In the following exercises...