Added IsNotMountPoint method to mount utils (pkg/util/mount/mount.go)
Added UnmountMountPoint method to volume utils (pkg/volume/util/util.go)
Call UnmountMountPoint method from local storage (pkg/volume/local/local.go)
IsLikelyNotMountPoint behavior was not modified, so the logic/behavior for UnmountPath is not modified
Automatic merge from submit-queue
Initial work on running windows containers on Kubernetes
<!-- Thanks for sending a pull request! Here are some tips for you:
1. If this is your first time, read our contributor guidelines https://github.com/kubernetes/kubernetes/blob/master/CONTRIBUTING.md and developer guide https://github.com/kubernetes/kubernetes/blob/master/docs/devel/development.md
2. If you want *faster* PR reviews, read how: https://github.com/kubernetes/kubernetes/blob/master/docs/devel/faster_reviews.md
3. Follow the instructions for writing a release note: https://github.com/kubernetes/kubernetes/blob/master/docs/devel/pull-requests.md#release-notes
-->
This is the first stab at getting the Kubelet running on Windows (fixes#30279), and getting it to deploy network-accessible pods that consist of Windows containers. Thanks @csrwng, @jbhurat for helping out.
The main challenge with Windows containers at this point is that container networking is not supported. In other words, each container in the pod will get it's own IP address. For this reason, we had to make a couple of changes to the kubelet when it comes to setting the pod's IP in the Pod Status. Instead of using the infra-container's IP, we use the IP address of the first container.
Other approaches we investigated involved "disabling" the infra container, either conditionally on `runtime.GOOS` or having a separate windows-docker container runtime that re-implemented some of the methods (would require some refactoring to avoid maintainability nightmare).
Other changes:
- The default docker endpoint was removed. This results in the docker client using the default for the specific underlying OS.
More detailed documentation on how to setup the Windows kubelet can be found at https://docs.google.com/document/d/1IjwqpwuRdwcuWXuPSxP-uIz0eoJNfAJ9MWwfY20uH3Q.
cc: @ikester @brendandburns @jstarks
Rohit Agarwal