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Introduction to Kubernetes

Overview​

This chapter provides a basic introduction to how Kubernetes manages applications within its environment. It delves into Kubernetes objects for different use cases and deployments on a local cluster, such as Deployments, Services, Secrets, and PersistentVolumeClaims, all integral to state, networking, and access management.

Objective​

This guide aims to expose you to Kubernetes' core components and functionalities. Its primary objective is to equip you with knowledge of the basic components of a Kubernetes environment.

Terms​

Kubernetes is an open-source container orchestration platform used to manage containerized applications. At a high level, Kubernetes consists of two main components: the Control Plane and Data Plane.

Control Plane​

The control plane manages the Kubernetes cluster by maintaining the desired state of the system. It includes the following components:

  • API Server: The API server is the front-end for the Kubernetes Control Plane. It handles and validates requests, and stores data in the etcd database.
  • etcd: etcd is a distributed key-value store used by Kubernetes to store configuration data.
  • Controller Manager: The Controller Manager is responsible for running controllers that regulate the state of the cluster.
  • Scheduler: The Scheduler assigns new workloads to nodes based on available resources and workload constraints.

Data Plane​

The data plane consists of nodes, which act as the worker machines that run the containerized applications. Each node runs a set of components that communicate with the Control Plane to maintain the desired state of the system. The main components running on a node are:

  • kubelet: The kubelet is responsible for managing the state of the node, including starting, stopping, and maintaining the containers on the node.
  • kube-proxy: The kube-proxy is responsible for network communication between services and pods in the cluster.
  • Container Runtime: The container runtime is responsible for pulling the container images from a registry and running them on the node.

Tools​

Before you begin, make sure that the following tools have been installed:

kubectl version --client
minikube version

If any of these tools are missing, refer to section Setting up the Development Environment for installation instructions.