Automatic merge from submit-queue
Attach/Detach Controller Kubelet Changes
This PR contains changes to enable attach/detach controller proposed in #20262.
Specifically it:
* Introduces a new `enable-controller-attach-detach` kubelet flag to enable control by attach/detach controller. Default enabled.
* Removes all references `SafeToDetach` annotation from controller.
* Adds the new `VolumesInUse` field to the Node Status API object.
* Modifies the controller to use `VolumesInUse` instead of `SafeToDetach` annotation to gate detachment.
* Modifies kubelet to set `VolumesInUse` before Mount and after Unmount.
* There is a bug in the `node-problem-detector` binary that causes `VolumesInUse` to get reset to nil every 30 seconds. Issue https://github.com/kubernetes/node-problem-detector/issues/9#issuecomment-221770924 opened to fix that.
* There is a bug here in the mount/unmount code that prevents resetting `VolumeInUse in some cases, this will be fixed by mount/unmount refactor.
* Have controller process detaches before attaches so that volumes referenced by pods that are rescheduled to a different node are detached first.
* Fix misc bugs in controller.
* Modify GCE attacher to: remove retries, remove mutex, and not fail if volume is already attached or already detached.
Fixes#14642, #19953
```release-note
Kubernetes v1.3 introduces a new Attach/Detach Controller. This controller manages attaching and detaching volumes on-behalf of nodes that have the "volumes.kubernetes.io/controller-managed-attach-detach" annotation.
A kubelet flag, "enable-controller-attach-detach" (default true), controls whether a node sets the "controller-managed-attach-detach" or not.
```
75ef1ca270