[Spot] Handle spot parameters in VPC instance creation

[meomnzak]

Description

Parent: #501
Design Doc: #523
Depends on: #529, #532

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Summary

Create() in the VPC instance provider currently assumes on-demand capacity.

Spot support requires:

• resolving capacity type from the NodeClaim
• setting VPC spot-specific API fields when applicable
• labelling the resulting node dynamically

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Goal

Update:

pkg/providers/vpc/instance/provider.go

to support spot-aware instance creation.

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Required Changes

1. Resolve capacity type

Early in Create(), call:

capacityType := capacitytype.ResolveCapacityType(nodeClaim, instanceTypes)

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2. Update availability policy

Current code:

instancePrototype.AvailabilityPolicy = &vpcv1.InstanceAvailabilityPolicyPrototype{
    HostFailure: &[]string{"restart"}[0],
}

Replace with capacity-type handling:

if capacityType == karpv1.CapacityTypeSpot {
    instancePrototype.Availability = &vpcv1.InstanceAvailabilityPrototype{
        Class: core.StringPtr(karpv1.CapacityTypeSpot),
    }
    instancePrototype.AvailabilityPolicy = &vpcv1.InstanceAvailabilityPolicyPrototype{
        Preemption: core.StringPtr("stop"),
    }
    instancePrototype.ReservationAffinity = &vpcv1.InstanceReservationAffinityPrototype{
        Policy: core.StringPtr("disabled"),
    }
} else {
    // Preserve existing on-demand behavior
    instancePrototype.AvailabilityPolicy = &vpcv1.InstanceAvailabilityPolicyPrototype{
        HostFailure: &[]string{"restart"}[0],
    }
}

Notes:

• Preemption: "stop" ensures an unambiguous stopped_by_preemption signal.
• reservation_affinity.policy = "disabled" is required for spot.

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3. Set capacity-type label dynamically

Current code:

karpv1.CapacityTypeLabelKey: "on-demand",

Replace with:

karpv1.CapacityTypeLabelKey: capacityType,

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Acceptance Criteria

• Create() resolves capacity type using helper
• Spot-specific VPC fields set when capacity type is spot
• Capacity-type label set dynamically
• Add Unit tests