This diagram is applicable to Kubernetes clusters launched with Rancher using RKE..

Lines show the traffic flow between components. Colors are used purely for visual aid

etcd

controlplane

Nodes with the controlplane role run the Kubernetes master components (excluding , as it’s a separate role). See for a detailed list of components.

The Kubernetes API server (kube-apiserver) scales horizontally. Each node with the role will be added to the NGINX proxy on the nodes with components that need to access the Kubernetes API server. This means that if a node becomes unreachable, the local NGINX proxy on the node will forward the request to another Kubernetes API server in the list.

The Kubernetes controller manager uses leader election using an endpoint in Kubernetes. One instance of the kube-controller-manager will create an entry in the Kubernetes endpoints and updates that entry in a configured interval. Other instances will see an active leader and wait for that entry to expire (for example, when a node is unresponsive).

worker

Nodes with the worker role run the Kubernetes node components. See for a detailed list of components.

References