Currently in Kubernetes when a pod is terminated (but not deleted from api server), the volume - pod was using although is unmounted from node is still kept attached to the node.

This creates problems if user tries to create another pod using same PVC.

Currently kubelet has a flag called --keep-terminated-pod-volumes that can force the volume to be mounted on the node for terminated pods (the flag isn't set by default). In such case, attach/detach controller shouldn't do force detach of the volume.

cc @kubernetes/sig-storage-bugs @eparis @ncdc