Add support for spot instances

TL;DR

This module supports preemptible instances, but not spot instances

Terraform Resources

We should be able to use provisioning_model = SPOT to support spot instances: https://registry.terraform.io/providers/hashicorp/google/latest/docs/resources/compute_instance_template#nested_scheduling

Detailed design

Add a "spot" variable in the model and set the provisioning_model here:

terraform-google-vm/modules/instance_template/main.tf

Lines 144 to 149 in dfb0523

    
           # scheduling must have automatic_restart be false when preemptible is true. 
        
           scheduling { 
        
             preemptible         = var.preemptible 
        
             automatic_restart   = !var.preemptible 
        
             on_host_maintenance = local.on_host_maintenance 
        
           }

Additional information

No response

This issue is stale because it has been open 60 days with no activity. Remove stale label or comment or this will be closed in 7 days

I believe this is still a valid issue

This issue is stale because it has been open 60 days with no activity. Remove stale label or comment or this will be closed in 7 days

This is still a valid issue

	# scheduling must have automatic_restart be false when preemptible is true.
	scheduling {
	preemptible = var.preemptible
	automatic_restart = !var.preemptible
	on_host_maintenance = local.on_host_maintenance
	}