What is the kubernetes master?

[shoebill]

The Master Node.

Runs three processes on a single node. Reference the diagram from the official kubernetes documentation.

• kube-apiserver
• kube-controller-manager
• kube-scheduler

kube-apiserver - preform REST operations to validate and configure data for objects: pods, services, replicationcontrollers, etc..
Also see: https://kubernetes.io/docs/reference/command-line-tools-reference/kube-apiserver/

kube-controller-manager - It is a single binary with multiple controller functions with it:

From Kubernetes documentation: https://kubernetes.io/docs/concepts/overview/components/

• Node Controller: Responsible for noticing and responding when nodes go down.

• Replication Controller: Responsible for maintaining the correct number of pods for every replication controller object in the system.

• Endpoints Controller: Populates the Endpoints object (that is, joins Services & Pods).

• Service Account & Token Controllers: Create default accounts and API access tokens for new namespaces.
  Also see: https://kubernetes.io/docs/reference/command-line-tools-reference/kube-controller-manager/

kube-scheduler - As all schedulers decides where things run, in this case pods. Also see: https://kubernetes.io/docs/reference/command-line-tools-reference/kube-scheduler/

For full information check this link: https://kubernetes.io/docs/concepts/overview/components/

Diagram without the Cloud Controller Manager.

The Kubernetes documentation for the Cloud Controller Manager: https://kubernetes.io/docs/concepts/architecture/cloud-controller/