Apply CPU startup boost in admission controller if its set #8458

kamarabbas99 · 2025-08-18T19:56:13Z

What type of PR is this?

/kind feature

What this PR does / why we need it:

Which issue(s) this PR fixes:

Introduces changes in the admission-controller component to apply cpu startup boost if its set in the vpa spec.
Also the original cpu request is added in annotation to verify if the updater correctly reverts back to original state.

Does this PR introduce a user-facing change?

Users can now configure a startupBoost policy in the VPA spec.

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

- [KEP]: (https://github.com/kubernetes/autoscaler/tree/master/vertical-pod-autoscaler/enhancements/7862-cpu-startup-boost#aep-7862-cpu-startup-boost)

Apply CPU startup boost in admission controller if its set

k8s-ci-robot · 2025-08-18T19:56:22Z

Hi @kamarabbas99. Thanks for your PR.

I'm waiting for a kubernetes 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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kamarabbas99 · 2025-08-18T19:56:57Z

/cc laoj2

adrianmoisey · 2025-08-18T20:36:14Z

/ok-to-test

adrianmoisey · 2025-08-19T08:44:52Z

This PR contains similar changes to #8417
I thought the plan was to split up into multiple changes?

Could we get #8417 merged first?

kamarabbas99 · 2025-08-19T15:27:04Z

@adrianmoisey yes I plan to rebase this once that PR is merged!

vertical-pod-autoscaler/pkg/utils/annotations/vpa_cpu_boost.go

vertical-pod-autoscaler/pkg/admission-controller/resource/pod/patch/resource_updates.go

adrianmoisey · 2025-08-27T20:23:05Z

I haven't gone over this in detail yet, just left some nits

vertical-pod-autoscaler/pkg/admission-controller/main.go

kwiesmueller · 2025-09-17T12:54:57Z

vertical-pod-autoscaler/pkg/admission-controller/resource/pod/patch/resource_updates.go

 	updatesAnnotation := []string{}
 	for i, containerResources := range containersResources {
+		// Apply startup boost if configured
+		if features.Enabled(features.CPUStartupBoost) {


This block is quite nested and complex. I'd prefer splitting it into smaller functions that reduce the cognitive complexity (less nesting) a little bit. Would make things easier to argue about.

omerap12

I need to go over the code again, but these are my initial comments

vertical-pod-autoscaler/pkg/admission-controller/resource/pod/patch/resource_updates.go

vertical-pod-autoscaler/docs/flags.md

vertical-pod-autoscaler/pkg/admission-controller/main.go

omerap12 · 2025-09-25T16:37:57Z

vertical-pod-autoscaler/pkg/admission-controller/resource/pod/patch/resource_updates.go

+	// Apply CPU Requests
+	if containerResources.Requests == nil {
+		containerResources.Requests = core.ResourceList{}
+	}
+	resourceList := core.ResourceList{core.ResourceCPU: *boostedRequest}
+	if controlledValues == vpa_types.ContainerControlledValuesRequestsOnly {
+		vpa_api_util.CapRecommendationToContainerLimit(resourceList, container.Resources.Limits)
+	}
+	containerResources.Requests[core.ResourceCPU] = resourceList[core.ResourceCPU]


Don't we need to check here the cpu is part of the controlledResources of the vpa object?

According to KEP, startupboost field takes priority over that.
https://github.com/kubernetes/autoscaler/tree/master/vertical-pod-autoscaler/enhancements/7862-cpu-startup-boost#priority-of-startupboost

Got it. thanks!

vertical-pod-autoscaler/pkg/admission-controller/main.go

adrianmoisey

It's looking good, I have a few comments

vertical-pod-autoscaler/pkg/admission-controller/resource/pod/patch/resource_updates.go

vertical-pod-autoscaler/pkg/admission-controller/resource/pod/patch/resource_updates_test.go

jackfrancis · 2025-09-30T16:48:54Z

/release-note-edit

Apply CPU startup boost in admission controller if its set

adrianmoisey · 2025-10-04T05:05:13Z

I'm good with this
/lgtm
/cc @omerap12

omerap12

Thanks! tested it and it worked ( there is one bug in the admission controller unrelated to that - will open an issue ).
/approve

k8s-ci-robot · 2025-10-04T11:14:44Z

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: kamarabbas99, omerap12

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Needs approval from an approver in each of these files:

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omerap12 · 2025-10-04T11:15:59Z

For people intests:

NAME          MODE   CPU   MEM     PROVIDED   AGE
example-vpa   Auto   25m   250Mi   True       5m43s

And if we take a look into a pod:

  kind: Pod
  metadata:
    annotations:
      startup-cpu-boost: '{"requests":{"cpu":"250m","memory":"100Mi"},"limits":{"cpu":"500m","memory":"200Mi"}}'

With:

      resources:
        limits:
          cpu: 150m
          memory: 500Mi
        requests:
          cpu: 75m
          memory: 250Mi

VPA configured as follows:

startupBoost:
    cpu:
      type: "Factor"
      factor: 3
      duration: 10s

k8s-ci-robot requested review from kwiesmueller and omerap12 August 18, 2025 19:56

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k8s-ci-robot requested a review from laoj2 August 18, 2025 19:56

kamarabbas99 changed the title ~~Feature cpu ac~~ Apply CPU startup boost in admission controller if its set Aug 18, 2025

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Apply CPU startup boost in admission controller if its set

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omerap12 mentioned this pull request Oct 4, 2025

VPA: Fix invalid VPA startupBoost example and unclear error message #8608

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Apply CPU startup boost in admission controller if its set #8458

Apply CPU startup boost in admission controller if its set #8458

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kamarabbas99 commented Aug 18, 2025 • edited by k8s-ci-robot Loading Uh oh! There was an error while loading. Please reload this page.

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