User Story

As a GCP administrator, I want to use a provisioningModel: "Spot" field to create worker nodes, so that I can leverage GCP Spot VMs for cost savings instead of the legacy preemptible flag.

Background

GCP now favors provisioningModel: "Spot" over the old preemptible field. This change aligns our API with the modern GCP standard for requesting interruptible instances.Steps

Steps

• Add provisioningModel field to the GCPMachineProviderSpec API.

• Update reconciler logic to set the SPOT provisioning model in the GCP compute API.

• Implement validation (webhook and reconciler) to forbid conflicts between preemptible and provisioningModel.

• Update related logic (restart policy, quotas, labels) for Spot instances.

• Add unit tests for the new API validation and reconciler logic.{}

Definition of Done

• provisioningModel field is added to the v1beta1 API.

• Reconciler creates Spot VMs when provisioningModel: "Spot" is set.

• Validation blocks using both preemptible and provisioningModel: "Spot"

Docs

• OpenShift docs updated to use Spot for interruptible instances. GCP encourages users to uset Spot instead of preemptible. OpenShift should also steer users toward spot over interruptible instances. https://docs.cloud.google.com/compute/docs/instances/preemptible

Testing

• Added unit tests to reconciler_test.go for Spot creation, restart policy, and validation errors.

• Added unit tests to machine_webhook_test.go to validate conflicting and invalid configurations.