Certified Kubernetes Application Developer (CKAD) Study Guide

Chapter 6. Pod Design

Of all the sections included in the CKAD curriculum, “Pod Design” has the most weight. This chapter is packed with a lot of concepts and intricacies you’ll have to understand to increase your chances of passing the exam.

We’ll start by reviewing labels, label selection, and annotations. As part of the discussion, we’ll compare the commonalities and differences between labels and annotations. Labels are an essential tool for querying, filtering, and sorting Kubernetes objects. Annotations only represent descriptive metadata for Kubernetes objects but have no ability to be used for queries. You will learn how to assign and use both concepts.

A big selling point of Kubernetes is rooted in its scalability and replication features. To support those features, Kubernetes offers the Deployment primitive. We’ll look at the creation of a Deployment scaled to multiple replicas, how to roll out a revision of your application, how to roll back to a previous revision, and how to use autoscalers to handle scaling concerns automatically based on the current workload.

Lastly, we’ll touch on the Kubernetes primitives Job and CronJob. A Job models a one-time process—for example, a batch operation. The Pod and its encompassed containers stop running after the work has been completed. CronJobs run periodically according to their defined schedules. A good application for a CronJob is a task that needs to occur continuously (for example, a process that exports data). You will learn ...