Minimal MachinePool support by justinsb · Pull Request #1506 · kubernetes-sigs/cluster-api-provider-gcp

justinsb · 2025-08-16T14:33:37Z

Initial spike: GCPMachinePool
GCPMachinePool: generated code/manifests

This continues the work started by @BrennenMM7 in #901 . I also combined in the support from cluster-api-provider-aws to see what we want to borrow from that, and will whittle the code we don't need from cluster-api-provider-aws away.


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justinsb · 2025-08-16T14:38:14Z

This PR is WIP while I whittle down the unneeded code from cluster-api-provider-aws and generally make this reviewable. But I am uploading as this is a checkpoint that works (in a limited way!)

justinsb · 2025-08-23T15:25:28Z

Removing the WIP. I will still try to whittle down the code by extracting helpers etc, but it's already approaching the reviewable ballpark!

justinsb · 2025-08-23T15:47:30Z

So the linter is blowing up on the TODO comments. How do we want to track next steps in code? If we don't want to do // TODO because golangci, maybe we do // TASK?

justinsb · 2025-12-22T20:13:02Z

Could we get this reviewed / approved?

damdo · 2025-12-22T21:11:13Z

Hey @justinsb I'm OOO but will prio this the first days of Jan as soon as I am back.
Thanks!

salasberryfin

/hold
/lgtm

Thanks @justinsb. I hold it so @damdo and @chrischdi can have time for a final review.

We should have a follow-up PR with a new section in the provider's book on how to use MachinePools. I'll create a separate issue.

damdo

Thanks a lot Justin!
This is looking good, left a couple of comments but it looks like we are already in great shape! TY

damdo · 2026-01-12T11:12:01Z

+			return nil, fmt.Errorf("creating instanceGroupManager %v: %w", selfLink, err)
+		}
+
+		actual, err = s.instanceGroupManagers.Get(ctx, igmKey)


Are you going to add the comment here or elsewhere? TY

damdo · 2026-01-12T11:23:31Z

+// ValidateCreate implements webhook.Validator so a webhook will be registered for the type.
+func (*gcpMachinePoolWebhook) ValidateCreate(_ context.Context, obj runtime.Object) (admission.Warnings, error) {
+	r, ok := obj.(*GCPMachinePool)
+	if !ok {
+		return nil, apierrors.NewBadRequest(fmt.Sprintf("expected a GCPMachinePool but got a %T", obj))
+	}
+
+	gcpMachinePoolLog.Info("Validating GCPMachinePool create", "name", r.Name)
+
+	return nil, nil
+}
+
+// ValidateUpdate implements webhook.Validator so a webhook will be registered for the type.
+func (*gcpMachinePoolWebhook) ValidateUpdate(_ context.Context, _, newObj runtime.Object) (admission.Warnings, error) {
+	r, ok := newObj.(*GCPMachinePool)
+	if !ok {
+		return nil, fmt.Errorf("expected a GCPMachinePool object but got %T", r)
+	}
+
+	gcpMachinePoolLog.Info("Validating GCPMachinePool update", "name", r.Name)
+
+	return nil, nil
+}
+
+// ValidateDelete implements webhook.Validator so a webhook will be registered for the type.
+func (*gcpMachinePoolWebhook) ValidateDelete(_ context.Context, obj runtime.Object) (admission.Warnings, error) {
+	r, ok := obj.(*GCPMachinePool)
+	if !ok {
+		return nil, apierrors.NewBadRequest(fmt.Sprintf("expected a GCPMachinePool but got a %T", obj))
+	}
+
+	gcpMachinePoolLog.Info("Validating GCPMachinePool delete", "name", r.Name)
+
+	return nil, nil
+}


Are we planning to add in the validation logic at a later stage?

I will add a few TODOs. I think we probably want to share logic with the machine validation. Does that work?

Sounds good thanks!

damdo · 2026-01-12T11:34:23Z

+	// Requeue so that we can keep the spec.providerIDList and status in sync with the MIG.
+	// This is important for scaling up and down, as the CAPI MachinePool controller relies on
+	// the providerIDList to determine which machines belong to the MachinePool.
+	return ctrl.Result{RequeueAfter: 1 * time.Minute}, nil


How are other providers that have implemented MachinePools doing this?

Co-authored-by: Christian Schlotter <christi.schlotter@gmail.com> Co-authored-by: Carlos Salas <salash66@gmail.com>

In order for nodes to be associated to the MachinePool, we need to populate the spec.providerIDList field. This field is known to the MachinePool controller. Co-authored-by: Christian Schlotter <christi.schlotter@gmail.com>

justinsb · 2026-01-15T15:19:39Z

So I think this looks pretty good (IMO) as a way to introduce the feature. I'm happy to split out InstanceNetworkInterfaceAliasIPRangesSpec into its own PR if we want more confidence that this is additive.

I think cleanup/deletion is tricky, but I think that machinepool has some logic to ensure that the gcpmachinepool is deleted first:
https://github.com/kubernetes-sigs/cluster-api/blob/main/internal/controllers/machinepool/machinepool_controller.go#L305-L340

So it looks like we are OK here, though I agree it's not the most obvious logic.

salasberryfin

Thanks @justinsb.

Overall this looks good to me as a first iteration of machine pools. I'll wait for others to resolve their comments but we're good to go in my opinion.

We should also create issues for all of the follow-up improvements, additions, etc. to keep track of what needs further refinement.

damdo

Thanks @justinsb

/approve
/lgtm

Thanks @justinsb
I think we are good here!

justinsb · 2026-01-30T15:43:53Z

Awesome thank you all! I opened issues for the follow ups that I identified (though I have likely missed some, and I'm sure we'll find more)

@salasberryfin I think you have a hold on this PR (which is why it is not merging) - is it OK to remove now?

salasberryfin

Sure, thanks @justinsb!

/lgtm
/unhold

k8s-ci-robot · 2026-01-30T15:46:09Z

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: damdo, justinsb, salasberryfin

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justinsb force-pushed the machinepool branch 5 times, most recently from 428790f to 5906e99 Compare August 16, 2025 19:42

justinsb mentioned this pull request Aug 16, 2025

chore: refactor InstanceAdditionalDiskSpec for reuse in MachinePool #1507

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justinsb changed the title ~~WIP: Minimal MachinePool support~~ Minimal MachinePool support Aug 23, 2025

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justinsb force-pushed the machinepool branch from 5906e99 to 5a021b8 Compare August 23, 2025 15:44

justinsb force-pushed the machinepool branch from 5a021b8 to 878060d Compare August 29, 2025 13:15

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justinsb force-pushed the machinepool branch from 878060d to 6449078 Compare August 29, 2025 16:09

justinsb mentioned this pull request Sep 5, 2025

tests: test with kubernetes 1.33.2 #1527

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justinsb force-pushed the machinepool branch from 6449078 to 2b81034 Compare September 6, 2025 00:25

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salasberryfin reviewed Dec 23, 2025

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Comment thread cloud/scope/machinepool.go

Comment thread exp/controllers/gcpmachinepool_controller.go

Comment thread exp/api/v1beta1/conditions_consts.go Outdated

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This was referenced Dec 23, 2025

Document how to use MachinePool #1574

Open

feat: implement proper context in scope methods #1575

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damdo reviewed Jan 12, 2026

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justinsb force-pushed the machinepool branch from 748e972 to cd6378b Compare January 15, 2026 13:59

justinsb commented Jan 15, 2026

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Comment thread cloud/scope/machine_test.go

justinsb and others added 4 commits January 15, 2026 14:26

Initial spike: GCPMachinePool

0cc301e

Co-authored-by: Christian Schlotter <christi.schlotter@gmail.com> Co-authored-by: Carlos Salas <salash66@gmail.com>

GCPMachinePool: generated code/manifests

4e85215

MachinePool: populate providerIDList

a51c644

In order for nodes to be associated to the MachinePool, we need to populate the spec.providerIDList field. This field is known to the MachinePool controller. Co-authored-by: Christian Schlotter <christi.schlotter@gmail.com>

MachinePool: support aliasIPRanges

793ea56

justinsb force-pushed the machinepool branch from cd6378b to 793ea56 Compare January 15, 2026 14:26

salasberryfin reviewed Jan 25, 2026

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damdo reviewed Jan 30, 2026

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This was referenced Jan 30, 2026

Implement Webhook Validation for GCPMachinePool #1603

Open

Fix Kube API Linter (KAL) Findings for GCPMachinePool #1604

Open

Refactor controllers to use paused.EnsurePausedCondition #1605

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salasberryfin approved these changes Jan 30, 2026

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k8s-ci-robot merged commit 6801574 into kubernetes-sigs:main Jan 30, 2026
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barbacbd mentioned this pull request Apr 8, 2026

REQUEST: New membership for barbacbd kubernetes/org#6277

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