feat: TargetPortNumber int32 to become TargetPorts []Port

[capri-xiyue]

part of #1336

1. change TargetPortNumber int32 to become TargetPorts []Port, where Port includes only a Number field to start in InferencePool v1.
2. to avoid break change for now, currently TargetPosts only allows exactly one item

Does this PR introduce a user-facing change?:

Replaces InferencePool targetPortNumber with targetPorts. Only 1 targetPort is supported at this time. Updates Helm values accordingly.

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[k8s-ci-robot]

Hi @capri-xiyue. 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.

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[liu-cong]

/ok-to-test

[capri-xiyue]

/assign @ahg-g

[capri-xiyue]

This is ready for early review. I will add additional conversion logic once #1330 gets merged.

/hold until #1330 gets merged

[capri-xiyue]

/assign @danehans @nirrozenbaum for InferencePool spec change.

[robscott]

Thanks @capri-xiyue! This LGTM, curious what others like @danehans and @nirrozenbaum think.

[robscott]

Thanks @capri-xiyue!

[nirrozenbaum]

I went over the PR.

the main comment I have is that I think this change is too tightly coupled with a specific way to do DP, while there are potentially multiple ways to do that.

if vLLM decides to shift from multiple ports to something else, we're going to get stuck with an array of size one.
I'm not a big fan of the approach that is suggested in this PR.

if we decide to pursue this path of multiple target ports on the CRD, this PR overall looks good. I left few comments.

[danehans]

If ExtensionRef continues to be required (xref), convertExtensionRefToV1() should return a value instead of a pointer. With that said, convert should be updated to return a value:

func convert[T any](u *unstructured.Unstructured) (T, error) {
	var res T
	if err := runtime.DefaultUnstructuredConverter.FromUnstructured(u.Object, &res); err != nil {
		var zero T
		return zero, fmt.Errorf("error converting unstructured to T: %v", err)
	}
	return res, nil
}

[capri-xiyue]

Changed ExtensionRef to be optional

[danehans]

Now that extRf is req, https://github.com/kubernetes-sigs/gateway-api-inference-extension/pull/1354/files#r2277929730 should be resolved.

[capri-xiyue]

I changed the conversion back to return value instead of pointer, but for the function parameter, I still use pointer as I thought it's a golang convention to pass parameter as a pointer for efficiency. Let me know whether it works for you.

Just curious, as ideally should both src and dst be a pointer for efficiency no matter whether they are required or not See https://github.com/kubernetes/kubernetes/blob/master/pkg/apis/batch/v1/zz_generated.conversion.go

[danehans]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: capri-xiyue, danehans

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