Certified Kubernetes Application Developer (CKAD) Study Guide, 2nd Edition

Chapter 5. Pods and Namespaces

The most important primitive in the Kubernetes API is the Pod. A Pod lets you run a containerized application. In practice, you’ll often encounter a one-to-one mapping between a Pod and a container; however, the use cases discussed in Chapter 8 benefit from declaring more than one container in a single Pod.

In addition to running a container, a Pod can consume other services like storage, configuration data, and much more. Therefore, think of a Pod as a wrapper for running containers while at the same time being able to mix in cross-cutting and specialized Kubernetes features.

Coverage of Curriculum Objectives

The curriculum doesn’t explicitly mention coverage of Pods and namespaces. However, you will definitely need to understand those primitives as they are essential for running workload in Kubernetes.

Working with Pods

In this chapter, we will look at working with a Pod running only a single container. We’ll discuss all important kubectl commands for creating, modifying, interacting, and deleting using imperative and declarative approaches.

Creating Pods

The Pod definition needs to state an image for every container. Upon creating the Pod object, imperatively or declaratively, the scheduler will assign the Pod to a node, and the container runtime engine will check if the container image already exists on that node. If the image doesn’t exist yet, the engine will download it from a container image registry. By default the registry is Docker ...