feat: CPU startup boost in master #9141

kamarabbas99 · 2026-01-28T19:38:47Z

What type of PR is this?

/kind feature
/kind api-change

What this PR does / why we need it:

The CPU startup boost changes were done on experimental branch, moving this to master.

Special notes for your reviewer:

Since #8813 didnt get submitted on time, it was hard to maintain it so as @adrianmoisey suggested I created new PR from local branch directly into master. All of the commits in this PR except the last one have already been reviewed.

Does this PR introduce a user-facing change?

Users can configure a startupBoost policy in the VPA spec.

Which issue(s) this PR fixes:

#7862

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)

Fix VPA startup boost validation error messages

k8s-ci-robot · 2026-01-28T19:38:57Z

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: kamarabbas99
Once this PR has been reviewed and has the lgtm label, please assign adrianmoisey for approval. For more information see the Code Review Process.

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k8s-triage-robot · 2026-01-28T20:43:43Z

This PR may require API review.

If so, when the changes are ready, complete the pre-review checklist and request an API review.

Status of requested reviews is tracked in the API Review project.

kamarabbas99 · 2026-01-28T20:56:05Z

/cc @soltysh
Do you mind doing API review(if left) on this instead of #8813 where you previously left comments?

vertical-pod-autoscaler/docs/features.md

soltysh · 2026-01-29T12:57:46Z

/label api-review

soltysh

I left a few comments for logic. From API shadow perspective this lgtm, I'll try to get API approval on it timely :)

soltysh · 2026-01-29T13:18:55Z

vertical-pod-autoscaler/pkg/updater/inplace/resource_updates.go

+	if vpa_api_util.GetUpdateMode(vpa) == vpa_types.UpdateModeOff {
+		// If update mode is "Off", we don't want to apply any recommendations,
+		// but we still want to unboost.
+		original, err := annotations.GetOriginalResourcesFromAnnotation(pod)


Since you're using annotations for keeping values from before the boost, what happens when the annotation is removed? Do you inform/warn users in some way about that fact?

When the annotations gets removed we just apply the recommendations which isnt too bad but if the vpa mode is
set to UpdateModeOff, the pod will remain boosted forever(but i think it might not be too common to use startup boost with update mode off).

Is there a way to warn users when they remove annotations?

soltysh · 2026-01-29T13:26:04Z

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

+	}
+}
+
+func TestGetOriginalResourcesFromAnnotation(t *testing.T) {


I'd suggest adding an error test case, where the annotation read will fail as well.

There are already test cases that cover all scenarios:

no annotation

Invalid json annotation

successful

vertical-pod-autoscaler/pkg/utils/vpa/api.go

vertical-pod-autoscaler/pkg/apis/autoscaling.k8s.io/v1/types.go

adrianmoisey · 2026-02-03T09:03:39Z

vertical-pod-autoscaler/pkg/apis/autoscaling.k8s.io/v1/types.go

+	// durationSeconds indicates for how long to keep the pod boosted after it goes to Ready.
+	// Defaults to 0.
+	// +optional
+	DurationSeconds *int32 `json:"durationSeconds,omitempty" protobuf:"varint,4,opt,name=durationSeconds"`


Can you also update the AEP to reflect this?
(In another PR I guess)

I updated in the same commit, should I make a new PR just for AEP?

Yes please.

liggitt · 2026-02-03T22:53:25Z

vertical-pod-autoscaler/charts/vertical-pod-autoscaler/crds/vpa-v1-crd-gen.yaml

+                                factor:
+                                  description: |-
+                                    factor specifies the factor to apply to the resource request.
+                                    This field is required when Type is "Factor".


where is this requirement enforced? I expected to see x-kubernetes-validations at the cpu level or something similar to enforce this

liggitt · 2026-02-03T22:53:30Z

vertical-pod-autoscaler/charts/vertical-pod-autoscaler/crds/vpa-v1-crd-gen.yaml

+                                  description: |-
+                                    quantity specifies the absolute resource quantity to be used as the
+                                    resource request and limit during the boost phase.
+                                    This field is required when Type is "Quantity".


where is this requirement enforced? I expected to see x-kubernetes-validations at the cpu level or something similar to enforce this

kamarabbas99 and others added 10 commits January 28, 2026 19:28

Introduce API changes and fetaure gate CPU startup boost

a8f8d7c

Apply CPU startup boost in admission controller if its set

850d274

Fix VPA startup boost validation error messages

081f7ab

Fix VPA startup boost validation error messages

Make changes to updater to add the unboosting logic

7b089fd

Fix test failure after rebase

c681156

Add e2e tests for CPU startup boost

6969a9f

Update VPA version for startupboost feature

5559d06

Address comments on kubernetes#8813

7daa9d5

Allow unboost even if pod replicas less than "min-replicas" flag

8e1b806

Fix startup boost workflow when limit is not set

68dfbad

k8s-ci-robot removed the do-not-merge/needs-area label Jan 28, 2026

k8s-ci-robot requested review from adrianmoisey and omerap12 January 28, 2026 19:38

k8s-ci-robot added the size/XXL Denotes a PR that changes 1000+ lines, ignoring generated files. label Jan 28, 2026

kamarabbas99 mentioned this pull request Jan 28, 2026

feat: CPU startup boost in master #8813

Closed

kamarabbas99 force-pushed the resolve-conflicts-cpu-boost branch 5 times, most recently from a687d83 to 419eedc Compare January 28, 2026 20:14

k8s-ci-robot requested a review from soltysh January 28, 2026 20:56

adrianmoisey reviewed Jan 29, 2026

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k8s-ci-robot added the api-review Categorizes an issue or PR as actively needing an API review. label Jan 29, 2026

github-project-automation bot added this to API Reviews Jan 29, 2026

soltysh moved this to Backlog in API Reviews Jan 29, 2026

soltysh reviewed Jan 29, 2026

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liggitt moved this from Backlog to Changes requested in API Reviews Jan 29, 2026

omerap12 mentioned this pull request Jan 29, 2026

Fix VPA verify scripts path resolution #9146

Merged

adrianmoisey mentioned this pull request Jan 30, 2026

Enable noduration and nobools kube-api-linter rule for VPA #9147

Merged

kamarabbas99 force-pushed the resolve-conflicts-cpu-boost branch 2 times, most recently from 9808ee6 to 245ad93 Compare February 2, 2026 19:52

Address new comments and Rebase on top of master

d8edd78

kamarabbas99 force-pushed the resolve-conflicts-cpu-boost branch from 245ad93 to d8edd78 Compare February 2, 2026 21:31

adrianmoisey reviewed Feb 3, 2026

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kamarabbas99 requested a review from liggitt February 3, 2026 15:56

kamarabbas99 mentioned this pull request Feb 3, 2026

Update Startup boost AEP after API review #9164

Open

liggitt reviewed Feb 3, 2026

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feat: CPU startup boost in master #9141

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feat: CPU startup boost in master #9141

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kamarabbas99 commented Jan 28, 2026

What type of PR is this?

What this PR does / why we need it:

Special notes for your reviewer:

Does this PR introduce a user-facing change?

Which issue(s) this PR fixes:

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

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