Kubernetes Cluster - Architecture

Cluster Architecture

K8 Component	Details
Worker Nodes	Physical or Virtual / On-Premise or Cloud nodes which hosts applications in form of pods and containers.
Master Nodes	Managing, planning, Scheduling and monitoring the worker nodes with the help of control plane components.
ETCD	Database which stores the information about the containers in the key-value pair.
Kube-scheduler	Identifies a right node (based on size, constraints, free space, etc) to place a containers
Controller-Manager	- Node-Controller: Onboarding new nodes to the cluster
	- Replication-Controller: To make sure desires nodes are available at all times
Kube-apiserver	Exposes the K8 api to perform management operations on the K8 cluster.
Kubelet	Kubelet is an engine which runs on each node and listens to the kupe-api server for any instructions
Kube-proxy	This services enables communication between the containers

• The master is made of multiple components like

K8 Component	Details
Kube-scheduler	Responsible for scheduling pods on the nodes
Kube-apiserver	Exposes the K8 api to perform management operations on the K8 cluster.
etcd (Distributed Database)	All the configuration changes, deployments details, scaling operations details, etc.
Kube-controller-manager	Used to manage the health of the k8 cluster

• By default, a Kubernetes cluster has one master, but it is possible to set up a multi-master Kubernetes cluster.
• A node, previously known as a minion, is a worker machine, usually a VM, but can also be a bare-metal machine.
• Each node comprises the required services used by the master to manage pods. e.g., Kubelet, the container runtime, and kube-proxy.