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

Annotations

As we have seen previously, labels are used to add the identifying metadata that we can later use to filter or select objects by. However, labels have certain constraints in terms of what we can store in the values, such as the limitation of 63 characters and alphanumeric characters at the beginning and end. Annotations, on the other hand, have fewer constraints in terms of what kind of data can be stored in them. However, we cannot filter or select objects by using annotations.

Annotations are also key-value pairs that can be used to store the unstructured information pertaining to the Kubernetes objects. Here is an example of how annotations in a YAML file would appear:

metadata:
  annotations:
    key1: value1
    key2: value2

Constraints for Annotations

As noted in the previous section, annotations are key-value pairs, just like labels. However, the rules for annotations are more relaxed than the rules for...