Certified Kubernetes Administrator (CKA) Study Guide

Chapter 5. Services and Networking

Applications running in a Kubernetes cluster rarely work in isolation. In the constellation of a microservices architecture, a set of applications running in their corresponding Pods need to work together. Kubernetes enables intracluster Pod-to-Service communication and communication with select Services from outside of the cluster with the help of various networking concepts. This domain of the CKA focuses on Services and networking aspects. You will need to understand the concept of a Service and an Ingress, as well as the cluster configuration that enables network communication.

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

• Kubernetes networking basics

• Connectivity between Pods

• Services, service types and their endpoints

• Ingress controller and Ingress

• Using and configuring CoreDNS

• Choosing a container network interface (CNI) plugin

Kubernetes Networking Basics

Kubernetes is designed as an operating system for managing the complexities of distributed data and computing. Workloads can be scheduled on a set of nodes to distribute the load. The Kubernetes network model enables networking communication and needs to fulfill the following requirements:

1. Container-to-container communication: Containers running in a Pod often need to communicate with each other. Containers within the same Pods can send Inter Process Communication (IPC) messages, share files, and most often communicate directly through the loopback interface ...