Certified Kubernetes Administrator (CKA) Study Guide

Chapter 4. Scheduling and Tooling

The scheduling portion of the CKA focuses on the effects of defining resource boundaries when evaluated by the Kubernetes scheduler. The default runtime behavior of the scheduler can also be modified by defining node affinity rules, as well as taints and tolerations. Of those concepts, you are expected only to understand the nuances of resource boundaries and their effect on the scheduler in different scenarios. Finally, this domain of the curriculum mentions high-level knowledge of manifest management and templating tools.

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

• Resource boundaries for Pods

• Imperative and declarative manifest management

• Common templating tools like Kustomize, yq, and Helm

Understanding How Resource Limits Affect Pod Scheduling

A Kubernetes cluster can consist of multiple nodes. Depending on a variety of rules (e.g., node selectors, node affinity, taints and tolerations), the Kubernetes scheduler decides which node to pick for running the workload. The CKA exam doesn’t ask you to understand the scheduling concepts mentioned previously, but it would be helpful to have a rough idea how they work on a high level.

One metric that comes into play for workload scheduling is the resource request defined by the containers in a Pod. Commonly used resources that can be specified are CPU and memory. The scheduler ensures that the node’s resource capacity can fulfill the resource requirements of the Pod. More ...