feat: Provide hostname for zonal disk insert API

[Rishita-Golla]

CL contains changes to pass in hostname for zonal disk.insert API as a part of location hint field. These changes are enabled behind a feature flag.

What type of PR is this?

/kind feature

What this PR does / why we need it:
To improve performance when provisioning PDs, we can optimize their placement by using the hostname of the VM. In case of delayed binding, since the VM is already known, we can use this information to pass hostname as a parameter to the driver's create volume requests. For PD creation, the hostname can be included in location hint field in the disks.insert call. This ensure the PD is created as close as possible to the VM, minimizing latency and cross-cell attachments.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:
Changes for regional disks will be part of future CLs.

Does this PR introduce a user-facing change?:

NONE

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: Rishita-Golla / name: Rishita Golla (ba2bb17)

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[APPROVALNOTIFIER] This PR is NOT APPROVED

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[mattcary]

/ok-to-test

[mattcary]

It would be nice to add some sort of test that we can actually fetch the PVC correctly. Otherwise we're relying only on the k8s integration tests, and it will be harder to catch a regression.

I'll have to think on how to do that, though. The local api server testing setup I usually use will be hard to use in this context. Maybe you can poke around k/k to see if there's a lightweight mock?

[Rishita-Golla]

True! I wanted to discuss about this, hence marked the PR as draft.
We could set up a mock client, but I'm not sure how useful/ how often it will be used in this repo. Will check in k/k if I find something.

[mattcary]

I think something where we can confirm the expected PVC query happens, and the returned name is correctly plumbed into the gcp insert request, would be enough.

[Rishita-Golla]

I'm thinking using this fake package will be a good idea. We can create a client with PVC resource and check the returned hostname. Let me know your thoughts on this.

[mattcary]

Yup, I think that should do the trick.

Be sure to have tests using this, and also when it's nil (ie the hostname flag is not set)

[Rishita-Golla]

Changes are not tested in staging yet due to a blocking issue. Updated the CL to include tests with fake-client and its imports.

[k8s-ci-robot]

@Rishita-Golla: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-gcp-compute-persistent-disk-csi-driver-verify	d4db94a	link	true	/test pull-gcp-compute-persistent-disk-csi-driver-verify
pull-gcp-compute-persistent-disk-csi-driver-e2e	d4db94a	link	true	/test pull-gcp-compute-persistent-disk-csi-driver-e2e

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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[k8s-ci-robot]

PR needs rebase.

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