Add support for InstanceTerminationAction for instance preemption.

[jwmay2012]

What type of PR is this?
/kind feature

What this PR does / why we need it:
Allows specifying for instances to be deleted instead of just stopped when the instance is preempted.

Special notes for your reviewer:
https://cloud.google.com/compute/docs/instances/create-use-spot#rest_1
https://registry.terraform.io/providers/hashicorp/google/latest/docs/resources/compute_instance#instance_termination_action

TODOs:

• squashed commits
• includes documentation
• adds unit tests

Release note:

Add support for InstanceTerminationAction for instance preemption. `GCPMachine.Spec.InstanceTerminationAction = "Delete"`

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: jwmay2012
Once this PR has been reviewed and has the lgtm label, please assign fabriziopandini for approval. For more information see the Kubernetes Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[k8s-ci-robot]

Hi @jwmay2012. Thanks for your PR.

I'm waiting for a kubernetes-sigs 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-sigs/prow repository.

[netlify]

✅ Deploy Preview for kubernetes-sigs-cluster-api-gcp ready!

Name	Link
🔨 Latest commit	8717e90
🔍 Latest deploy log	https://app.netlify.com/sites/kubernetes-sigs-cluster-api-gcp/deploys/66f2e92407e12a0008f6b8a4
😎 Deploy Preview	https://deploy-preview-1315--kubernetes-sigs-cluster-api-gcp.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[salasberryfin]

/ok-to-test

Thanks for working on this @jwmay2012

[jwmay2012]

I tested this code and it works. It's only supposed to be used with Spot VMs. Not STANDARD or the older preemptible VMs.
Normal behavior is the VM gets stopped, and the Node registers as UNKNOWN or shutdown/failed.

The result with InstanceTerminationAction="Delete" is the Node gets deleted from the workload cluster along with the instance, but the Machine from the management cluster is still present and revives a Zombie instance. If that Spot instance was deleted via the console, it can come back online running. If that Spot instance was deleted via a preemption, it comes back Stopped. In both cases, the previous Node never returns and you end up with a Machine without a Node.

🤷🏻‍♂️

This isn't as helpful as I was hoping it would be. I was hoping this would allow Spot machines to get automatically re-created when a VM is preempted. But no.

It might be worth it to have this option exposed, but I don't know if I can consider it useful given how CAPI reacts (or doesn't react) to it.

Up to you :D