If I create a POD manifest (pod-definition.yaml) and set the restartPolicy: Always does that Pod also need to be associated with any controller (i.e., a Replicaset or Deployment)? The end goal here it to auto-start the container in the Pod should it die. Without a Pod being associated with a controller will that container automatically restart? What happens if the Pod has only one container?
The documentation is not clear here but it lead me to believe that the Pod must be under a controller for this to work, i.e., if you implicitly create a 8Ks object and specify a restart policy of Never you'll get a pod. If you specify always (the default) you'll get a deployment.
Pod without a controller(deployment, replication controller etc) and only with restartPolicy will not be restarted/rescheduled if the node(to be exact the kubelet on that node) where its running dies or drained or rebooted or for some other reason pod is evicted from the node. If the node is in good state and for some reason pod crashes it will be restarted on the same node without the need of a controller.
The reason is pod restartPolicy is handled by kubelet i.e pod is restarted by kubelet of the node.Now if the node dies kubelet is also dead and can not restart the pod. Hence you need to have a controller which will restart it in another node.
From the docs
restartPolicy only refers to restarts of the Containers by the kubelet on the same node
In short if you want pods to survive a node failure or a kubelet failure of a node you should have a higher level controller.