Introduction

Kubernetes clusterizes container hosts (but not limited to, Docker hosts)

Provides load balancing & fault-tolerance across container hosts

Kubernetes Runtime

Kubernetes removed the built-in support for Docker in v1.24 (2022).

• Docker still continues to work for Kubernetes as a third party runtime (via the **cri-dockerd** shim).
• But Docker is now seeing less adoptions for Kubernetes.

The big names in the industry has already switched away from Docker to containerd, or to CRI-O:

• Adopters of containerd: Amazon Elastic Kubernetes Service (EKS), Azure Kubernetes Service (AKS), Google Kubernetes Engine (GKE), k3s, etc.
  • containerd focuses on extensibility and supports non-Kubernetes workloads as well as Kubernetes workloads.
  • It was originally made for Docker in 2015.
• Adopters of CRI-O: Red Hat OpenShift, Oracle Container Engine for Kubernetes (OKE), etc.
  • CRI-O focuses on simplicity and solely supports Kubernetes.

Kubernetes Cluster

Cluster → Collection of Nodes

Node → Master, Worker (Minion)

Core Components of Kubernetes

kube-api

scheduler

controller-manager

etcd

kubectl