The kubernetes cluster control plane runs on one more more master nodes. The components are:
1. etcd - a key value datastore containing the configuration data of the cluster.
2. The api-server is a server which serves and updates the state of the kubernetes cluster. It watches etcd and keeps the clusters actual state in sync with its desired state.
3. The scheduler is a component which selects on which node an unscheduled pod should run, based on what each pod needs and what the nodes in the cluster can support.
4. The controller manager manages several controllers which keep the cluster in sync with its desired state.