The Kubernetes master nodes are where the core control plane services live; not all services have to reside on the same node; however, for centralization and practicality, they are often deployed this way. This obviously raises services availability questions; however, they can easily be overcome by having several nodes and providing load balancing requests to achieve a highly available set of master nodes.
The master nodes are composed of four basic services:
- The kube-apiserver
- The kube-scheduler
- The kube-controller-manager
- The etcd database
Master nodes can either run on bare metal servers, virtual machines, or a private or public cloud, but it is not recommended to run container workloads on them. We will see more on this later.
The following diagram shows the Kubernetes master nodes components:
