Introduce API changes and feature gate CPU startup boost #8417

kamarabbas99 · 2025-08-07T19:14:26Z

What type of PR is this?

/kind feature
/kind api-change

What this PR does / why we need it:

API Extension: Adds a startupBoost field to the VerticalPodAutoscalerSpec and ContainerResourcePolicy to allow users to define a boost factor or quantity and a
duration.

Which issue(s) this PR fixes:

Fixes #7862

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)

k8s-ci-robot · 2025-08-07T19:14:36Z

Hi @kamarabbas99. Thanks for your PR.

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adrianmoisey · 2025-08-07T19:22:38Z

/ok-to-test

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

kamarabbas99 · 2025-08-07T20:31:36Z

/cc omerap12 laoj2

omerap12

Also missing validation: https://github.com/kubernetes/autoscaler/tree/master/vertical-pod-autoscaler/enhancements/7862-cpu-startup-boost#validation

This PR introduces API changes - so we need to adjust all API related stuff including validation.

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

omerap12 · 2025-08-08T08:20:00Z

vertical-pod-autoscaler/pkg/features/versioned_features.go


 // Entries are alphabetized.
 var defaultVersionedFeatureGates = map[featuregate.Feature]featuregate.VersionedSpecs{
+	CPUStartupBoost: {


Does CPUStartupBoost correct? I will never understand this stuff .. lol
@adrianmoisey, you are the expert on this

Yup, in this place it's correct (from what I understand)

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

adrianmoisey · 2025-08-09T09:00:00Z

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

+	// Defaults to "Factor".
+	// +unionDiscriminator
+	// +required
+	Type *StartupBoostType `json:"type,omitempty" protobuf:"bytes,1,opt,name=type"`


Required field shouldn't have omitempty: https://github.com/kubernetes-sigs/kube-api-linter/blob/main/docs/linters.md#requiredfields

Suggested change

Type *StartupBoostType `json:"type,omitempty" protobuf:"bytes,1,opt,name=type"`

Type *StartupBoostType `json:"type" protobuf:"bytes,1,opt,name=type"`

Made it optional with a default value.

You should make the unionDiscriminator required field, to avoid any defaulting logic and unexpected outcomes. So change +optional to Required and make this not pointer.

Another important question, are you planning other boost types? The reason I'm asking is on one had you're creating a targetted type CPUStartupBoost but inside it you're using generic StartupBoostType. The CPUStartupBoost as I'm reading doesn't have any cpu-specific elements. Hence my question, if you only plan to support CPU, I'd use CPUStartupBoostType. If you're planning to expand StartupBoost in the future with memory, will MemoryStartupBoostType look similar or differently from the current CPUStartupBoost? In general several nested structures (like here) don't play well. For example compare Device in resource/v1beta1 vs Device in resource/v1, in the latter case we squashed the BasicDevice to simplify the nesting. That's why I'm asking for future plans, before going with too many levels in the API.

adrianmoisey · 2025-08-09T09:00:50Z

vertical-pod-autoscaler/pkg/features/versioned_features.go


 // Entries are alphabetized.
 var defaultVersionedFeatureGates = map[featuregate.Feature]featuregate.VersionedSpecs{
+	CPUStartupBoost: {


Yup, in this place it's correct (from what I understand)

vertical-pod-autoscaler/pkg/features/features.go

adrianmoisey · 2025-08-09T09:05:42Z

vertical-pod-autoscaler/pkg/admission-controller/resource/vpa/handler.go

+	if boostType == nil {
+		// Default to Factor when type is not specified.
+		defaultType := vpa_types.FactorStartupBoostType
+		boostType = &defaultType
+	}


I see that in the API type is marked as required, I'm wondering if that is incorrect?

Made the API field optional with default value of Factor.

vertical-pod-autoscaler/pkg/admission-controller/resource/vpa/handler.go

laoj2 · 2025-08-11T13:33:22Z

vertical-pod-autoscaler/pkg/features/versioned_features.go

 // Entries are alphabetized.
 var defaultVersionedFeatureGates = map[featuregate.Feature]featuregate.VersionedSpecs{
+	CPUStartupBoost: {
+		{Version: version.MustParse("1.5"), Default: false, PreRelease: featuregate.Alpha},


@adrianmoisey with InPlaceOrRecreate graduating to Beta in 1.5 (https://github.com/kubernetes/autoscaler/pull/8423/files), does it make sense to make CPU boost available in 1.6+? So it doesn't block the graduation?

Not sure I understand, are you suggestion that CPUStartupBoost be available in 1.6 as alpha (default off) or as something else?
Why can't CPUStartupBoost be available as alpha (default off) in 1.5?

It could be available as alpha in 1.5. I'm suggesting that we could release CPU boost in another version (e.g 1.6), because CPU boost is not code complete/(stable too?) yet and we may want to cut a new VPA 1.5.0 release soon (to introduce InPlaceOrRecreate beta) without being blocked by this feature.

I see.
Well, if this feature is ready by the time we cut 1.5.0 (which may be soon after Kubernetes 1.34, I assume?), then it can go into 1.5.0.
If the feature is not code complete, and PRs not merged into 1.5.0, that's fine too, we just wait until 1.6.0

Agree with Adrian.

vertical-pod-autoscaler/pkg/admission-controller/resource/vpa/handler_test.go

kamarabbas99 · 2025-08-14T21:14:46Z

Made some API changes to address concerns by @soltysh.

Now we use GenericStartupBoost which can also be used by memory boost in case we plan to extend. Also Factor is not default based on @soltysh suggestion and I will update KEP on master in a seperate PR.

adrianmoisey · 2025-08-21T15:05:36Z

The tests are still failing with:

VPA flags documentation has been generated in /home/runner/work/autoscaler/autoscaler/go/src/k8s.io/autoscaler/vertical-pod-autoscaler/hack/../docs/flags.md
VPA flags are not up to date. Please run /home/runner/work/autoscaler/autoscaler/go/src/k8s.io/autoscaler/vertical-pod-autoscaler/hack/../hack/generate-flags.sh

kamarabbas99 · 2025-08-21T15:53:36Z

Thanks @adrianmoisey!! I thought those are unrelated formatting errors.

omerap12

Thanks!
Seems ok to me.
/lgtm

adrianmoisey · 2025-08-23T12:08:44Z

/retitle Introduce API changes and feature gate CPU startup boost

adrianmoisey · 2025-08-23T12:08:57Z

/approve

k8s-ci-robot · 2025-08-23T12:09:26Z

[APPROVALNOTIFIER] This PR is APPROVED

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

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omerap12 · 2025-08-23T15:57:08Z

/release-note-none

alextarasov-spot · 2025-11-13T11:10:24Z

Hello guys, when is this change scheduled to be released? Thanks!

adrianmoisey · 2025-11-13T12:01:32Z

Hey,
There is no timeline. It could be close to when the next version of Kubernetes is released, or the one after that. But no promises on when it will be released.

alextarasov-spot · 2025-11-13T16:21:12Z

Hey, There is no timeline. It could be close to when the next version of Kubernetes is released, or the one after that. But no promises on when it will be released.

Thank you for your response. I came across this draft PR #8413 and wanted to check if it's still relevant. I noticed there are some changes concerning the updater that haven't been implemented in that PR.

omerap12 · 2025-11-13T16:33:11Z

Hey, There is no timeline. It could be close to when the next version of Kubernetes is released, or the one after that. But no promises on when it will be released.

Thank you for your response. I came across this draft PR #8413 and wanted to check if it's still relevant. I noticed there are some changes concerning the updater that haven't been implemented in that PR.

I think this feature will be available soon, we have a dedicated branch for this work (which will be merged to master after the work is done ). there is currently a live PR for e2e test here: #8672
So most of the work is already done

k8s-ci-robot requested review from jbartosik and raywainman August 7, 2025 19:14

k8s-ci-robot added size/L Denotes a PR that changes 100-499 lines, ignoring generated files. and removed do-not-merge/needs-area labels Aug 7, 2025

kamarabbas99 mentioned this pull request Aug 7, 2025

VPA: Implement startup CPU boost support #8413

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kamarabbas99 mentioned this pull request Aug 18, 2025

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

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Introduce API changes and fetaure gate CPU startup boost

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k8s-ci-robot changed the title ~~Introduce API changes and fetaure gate CPU startup boost~~ Introduce API changes and feature gate CPU startup boost Aug 23, 2025

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This was referenced Oct 5, 2025

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

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REQUEST: New membership for kamarabbas99 kubernetes/org#5904

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adrianmoisey mentioned this pull request Nov 14, 2025

feat: CPU startup boost in master #8813

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	Type *StartupBoostType `json:"type,omitempty" protobuf:"bytes,1,opt,name=type"`
	Type *StartupBoostType `json:"type" protobuf:"bytes,1,opt,name=type"`

Introduce API changes and feature gate CPU startup boost #8417

Introduce API changes and feature gate CPU startup boost #8417

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kamarabbas99 commented Aug 7, 2025

What type of PR is this?

What this PR does / why we need it:

Which issue(s) this PR fixes:

Does this PR introduce a user-facing change?

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

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