Kubernetes in the Enterprise

Chapter 2. Fundamental Kubernetes Topics

In this chapter, we provide an introduction to the basic foundations of Kubernetes. We begin with an overview of the Kubernetes architecture and its deployment models. Next, we describe a few options for running Kubernetes and describe a variety of deployment environments. We then describe and provide examples of several fundamental Kubernetes concepts including Pods, labels, annotations, ReplicaSets, and Deployments.

Kubernetes Architecture

Kubernetes architecture at a high level is relatively straightforward. It is composed of a master node and a set of worker nodes. The nodes can be either physical servers or virtual machines (VMs). Users of the Kubernetes environment interact with the master node using either a command-line interface (kubectl), an application programming interface (API), or a graphical user interface (GUI). The master node is responsible for scheduling work across the worker nodes. In Kubernetes, the unit of work that is scheduled is called a Pod, and a Pod can hold one or more container. The primary components that exist on the master node are the kube-apiserver, kube-scheduler, etcd, and the kube-controller-manager:

kube-apiserver

The kube-apiserver makes available the Kubernetes API that is used to operate the Kubernetes environment.

kube-scheduler

The kube-scheduler component is responsible for selecting the nodes on which Pods should be created.

kube-controller-manager

Kubernetes provides several high-level abstractions ...