Google Driver: Enable AutoDelete of Disks for GCE

[tmaier]

This is how currently my disk listing looks like (this are gitlab-runners, started/managed with docker-machine and using Preemptible VMs)

Note that most disks are there, but not attached to any VM.
The related VMs are gone.

This means disks are not reliably deleted. For example when using together with Preemptible VMs. It can happen that the Disk stays forever.

This Pull request enables the auto-delete feature for disks.
https://cloud.google.com/sdk/gcloud/reference/compute/instances/set-disk-auto-delete
The documentation states that this is a feature which is enabled by default usually.

[GordonTheTurtle]

Please sign your commits following these rules:
https://github.com/moby/moby/blob/master/CONTRIBUTING.md#sign-your-work
The easiest way to do this is to amend the last commit:

$ git clone -b "google-AutoDelete" git@github.com:tmaier/machine.git somewhere
$ cd somewhere
$ git commit --amend -s --no-edit
$ git push -f

Amending updates the existing PR. You DO NOT need to open a new one.

[dgageot]

@tmaier The idea behind that was to be able to delete a machine and keep the disk to save money while not losing the data. That's what is done when we run docker-machine stop VM. Now, I admit that the code was written at the time where VMs couldn't be stopped on GCE.

What I'd rather see is a more important code change:

• Disks are auto-deleted
• docker-machine stop VM now actually stops a VM instead of deleting it.
• docker-machine rm VM should delete the VM. The disk will then be deleted automatically
• docker-machine start VM should start a stopped VM and complain if it's gone

Do you think it would address your issue?

[dgageot]

@tmaier I changed my mind. I think you are right. I based my thinking on the old behavior of the driver. LGTM then!

[tmaier]

Thank you!