Replication Controller

A Replication Controller is a Kubernetes abstraction which ensures that a specific number of pods are running at all times. If a pod or host goes down, the replication controller ensures enough pods get recreated elsewhere.

A pod template is used to define what each pod should look like (e.g. the docker container image to use, it's ports and environment variables etc).

The containers generated can have labels so that containers can be filtered to create Services.