Certified Kubernetes Application Developer (CKAD) Study Guide

Chapter 2. Core Concepts

By “core concepts,” the CKAD curriculum is referring to Kubernetes’ basic concepts, its API, and the commands to operate an application on Kubernetes. In this chapter, we’ll discuss the basic structure of Kubernetes primitives and the main entry point for interacting with them: the command line–based client, kubectl.

A Pod is the Kubernetes primitive for running an application in a container. We’ll touch on the predominant aspects of a Pod and also briefly discuss Docker, the containerization technology employed by Kubernetes.

At the end of the chapter, you’ll understand how to create Kubernetes objects imperatively and declaratively and know how to create a Pod and define its most basic configuration.

At a high level, this chapter covers the following concepts:

• Container concepts

• Pod

• Namespace

Kubernetes Primitives

Kubernetes primitives are the basic building blocks anchored in the Kubernetes architecture for creating and operating an application on the platform. Even as a beginner to Kubernetes, you might have heard of the terms Pod, Deployment, and Service, all of which are Kubernetes primitives. There are many more that serve a dedicated purpose in the Kubernetes architecture.

To draw an analogy, think back to the concepts of object-oriented programming. In object-oriented programming languages, a class defines the blueprint of a real-world functionality: its properties and behavior. A Kubernetes primitive is the equivalent of a class. The ...