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Control Plane

What are the main components of a Kubernetes cluster?

Master Node

  • ETCD
    Stores the configuration details and essential values.

  • Scheduler
    Assigns tasks to the worker nodes.

  • API Server

  • Performs all operations on the cluster.

  • Acts as a central management entity that receives all REST requests for modifications, serving as a frontend to the cluster.

  • Controller Manager(s)
    Includes:

  • Endpoints controller
  • Service accounts controller
  • Namespace controller
  • Node controller
  • Token controller
  • Replication controller

Worker Node

  • Pod

  • A pod is one or more containers controlled as a single application.

  • Container Runtime

  • Runs applications in an isolated, lightweight operating environment.

  • Responsible for pulling and running containers from Docker images.

  • Kubelet

  • Conveys information to and from the control plane service.

  • Maintains the work status and the node server.

  • Kube Proxy

  • Acts as a load balancer and network proxy for services on a single worker node.
  • Manages pods, volumes, secrets, container creation, health checks, etc.
  • Runs on every node to make services available to external hosts.