Add support for building Hyperv images

[baude]

Add a buildextend-hyperv command that creates a hyperv image in VHDX format.

Supports coreos/fedora-coreos-tracker#1411

[openshift-ci]

Hi @baude. Thanks for your PR.

I'm waiting for a coreos member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[bgilbert]

/ok-to-test

[bgilbert]

Thanks for the PR!

[bgilbert]

Diff LGTM.

"Add HyperV support" is a bit ambiguous as a commit message title, and the commit body has a similar issue. Could you update the commit message to clarify that the commit is adding support for building a hyperv image?

[dustymabe]

trivial LGTM

[bgilbert]

The commit text is better, but still claims to implement more than we're actually doing at this phase. Proposal:

Add support for building HyperV images

Add a buildextend-hyperv command that creates a `hyperv` image in VHDX
format.

Supports https://github.com/coreos/fedora-coreos-tracker/issues/1411.

(We don't use signoffs generally.)

[baude]

Ok, amended and fixor'd up in gh too.

[bgilbert]

Followup in #3546.