feat(api): introduce OptimizationJob CRD under Trainer by aniket2405 · Pull Request #3552 · kubeflow/trainer

aniket2405 · 2026-05-26T13:55:11Z

What this PR does / why we need it:

This PR introduces the core API schema for the OptimizationJob CRD. This is a foundational step in the consolidation of Katib hyperparameter tuning into the Trainer v2 ecosystem.

By integrating OptimizationJob natively under the trainer.kubeflow.org API group, we unify the user experience and enable shared observability with TrainJobs.

Key features of this API schema:

CEL-Native Validation: Implements server-side CEL validation for SearchSpace and TrialConfig constraints, ensuring high-quality hyperparameter search configurations at the API layer.

Declarative HPO: Enables the OptimizationJob -> TrainJob hierarchy, leveraging TrainJob's native progress tracking to eliminate the legacy Katib DB dependency.

Manifests & Tooling: Scaffolds all necessary deepcopy, clientset, RBAC, and CRD manifests.

Which issue(s) this PR fixes:
Fixes #3749

Checklist:

API design documentation (KEP) submitted in feat: KEP-3562: Introduce OptimizationJob CRD #3565.
Docs included if any changes are user facing.

Special notes for reviewers:

Autogenerated Code: Please note that ~18k lines of this PR consist of autogenerated manifests, zz_generated.deepcopy.go, and clientset code.

Core Logic: Focus your review efforts on api/v1alpha1/optimizationjob_types.go (the API schema), pkg/webhooks/ and the test/integration/webhooks directory (the validation and defaulting logic).

github-actions · 2026-05-26T13:56:45Z

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Copilot

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

This PR introduces the OptimizationJob v1alpha1 API surface and wires it through the generated Kubernetes clients (clientset, informer, lister), CRDs, OpenAPI, applyconfigurations, and the generated Python SDK models.

Changes:

Add OptimizationJob CRD + Go API types (OptimizationJobSpec/Status and related structs like Algorithm, SearchSpace, TrialConfig).
Generate/extend Go clientset, informers, listers, applyconfiguration helpers, and OpenAPI definitions for the new resource.
Generate Python OpenAPI client models for the new types.

Reviewed changes

Copilot reviewed 33 out of 43 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
pkg/client/listers/trainer/v1alpha1/optimizationjob.go	Adds lister interfaces/implementations for `OptimizationJob`.
pkg/client/listers/trainer/v1alpha1/expansion_generated.go	Adds lister expansion hooks for `OptimizationJob`.
pkg/client/informers/externalversions/trainer/v1alpha1/optimizationjob.go	Adds shared informer for `OptimizationJob`.
pkg/client/informers/externalversions/trainer/v1alpha1/interface.go	Exposes `OptimizationJobs()` informer on the v1alpha1 interface.
pkg/client/informers/externalversions/generic.go	Enables generic informer lookup for `optimizationjobs`.
pkg/client/clientset/versioned/typed/trainer/v1alpha1/trainer_client.go	Exposes typed client method `OptimizationJobs(namespace)`.
pkg/client/clientset/versioned/typed/trainer/v1alpha1/optimizationjob.go	Adds typed REST client for `OptimizationJob` including Apply/Status.
pkg/client/clientset/versioned/typed/trainer/v1alpha1/generated_expansion.go	Adds typed client expansion hook for `OptimizationJob`.
pkg/client/clientset/versioned/typed/trainer/v1alpha1/fake/fake_trainer_client.go	Adds fake typed client method `OptimizationJobs(namespace)`.
pkg/client/clientset/versioned/typed/trainer/v1alpha1/fake/fake_optimizationjob.go	Adds fake typed client implementation for `OptimizationJob`.
pkg/client/applyconfiguration/utils.go	Registers applyconfiguration `ForKind` mappings for new types.
pkg/client/applyconfiguration/trainer/v1alpha1/trialconfig.go	Adds applyconfiguration builder for `TrialConfig`.
pkg/client/applyconfiguration/trainer/v1alpha1/settingkv.go	Adds applyconfiguration builder for `SettingKV`.
pkg/apis/trainer/v1alpha1/zz_generated.openapi.go	Adds OpenAPI definitions for `OptimizationJob` and related types.
pkg/apis/trainer/v1alpha1/optimizationjob_types.go	Introduces the `OptimizationJob` API types and validation markers.
pkg/apis/trainer/v1alpha1/groupversion_info.go	Registers `OptimizationJob` types into the scheme.
manifests/base/crds/trainer.kubeflow.org_optimizationjobs.yaml	Adds CRD manifest for `OptimizationJob` (base manifests).
charts/kubeflow-trainer/crds/trainer.kubeflow.org_optimizationjobs.yaml	Adds CRD manifest for `OptimizationJob` (Helm chart).
hack/violation_exception_v1alpha1.list	Adds API rule violation exceptions for missing list-type markers.
api/openapi-spec/swagger.json	Updates swagger spec with new schemas.
api/python_api/kubeflow_trainer_api/models/trainer_v1alpha1_trial_config.py	Adds Python model for `TrialConfig`.
api/python_api/kubeflow_trainer_api/models/trainer_v1alpha1_setting_kv.py	Adds Python model for `SettingKV`.
api/python_api/kubeflow_trainer_api/models/trainer_v1alpha1_search_space.py	Adds Python model for `SearchSpace`.
api/python_api/kubeflow_trainer_api/models/trainer_v1alpha1_parameter_assignment.py	Adds Python model for `ParameterAssignment`.
api/python_api/kubeflow_trainer_api/models/trainer_v1alpha1_parameter.py	Adds Python model for `Parameter`.
api/python_api/kubeflow_trainer_api/models/trainer_v1alpha1_optimization_job_status.py	Adds Python model for `OptimizationJobStatus`.
api/python_api/kubeflow_trainer_api/models/trainer_v1alpha1_optimization_job_spec.py	Adds Python model for `OptimizationJobSpec`.
api/python_api/kubeflow_trainer_api/models/trainer_v1alpha1_optimization_job_list.py	Adds Python model for `OptimizationJobList`.
api/python_api/kubeflow_trainer_api/models/trainer_v1alpha1_optimization_job.py	Adds Python model for `OptimizationJob`.
api/python_api/kubeflow_trainer_api/models/trainer_v1alpha1_objective.py	Adds Python model for `Objective`.
api/python_api/kubeflow_trainer_api/models/trainer_v1alpha1_best_trial.py	Adds Python model for `BestTrial`.
api/python_api/kubeflow_trainer_api/models/trainer_v1alpha1_algorithm.py	Adds Python model for `Algorithm`.
api/python_api/kubeflow_trainer_api/models/init.py	Exports the newly generated Python models.

Files not reviewed (10)

pkg/apis/trainer/v1alpha1/zz_generated.deepcopy.go: Language not supported
pkg/client/applyconfiguration/trainer/v1alpha1/algorithm.go: Language not supported
pkg/client/applyconfiguration/trainer/v1alpha1/besttrial.go: Language not supported
pkg/client/applyconfiguration/trainer/v1alpha1/objective.go: Language not supported
pkg/client/applyconfiguration/trainer/v1alpha1/optimizationjob.go: Language not supported
pkg/client/applyconfiguration/trainer/v1alpha1/optimizationjobspec.go: Language not supported
pkg/client/applyconfiguration/trainer/v1alpha1/optimizationjobstatus.go: Language not supported
pkg/client/applyconfiguration/trainer/v1alpha1/parameter.go: Language not supported
pkg/client/applyconfiguration/trainer/v1alpha1/parameterassignment.go: Language not supported
pkg/client/applyconfiguration/trainer/v1alpha1/searchspace.go: Language not supported

Comments suppressed due to low confidence (1)

pkg/client/informers/externalversions/trainer/v1alpha1/interface.go:1

Grammar: change 'a OptimizationJobInformer' to 'an OptimizationJobInformer'.

@@ -0,0 +1,170 @@
+/*
+Copyright 2026 The Kubeflow Authors.
+


+API rule violation: list_type_missing,github.com/kubeflow/trainer/v2/pkg/apis/trainer/v1alpha1,OptimizationJobSpec,Objectives
+API rule violation: list_type_missing,github.com/kubeflow/trainer/v2/pkg/apis/trainer/v1alpha1,OptimizationJobSpec,Parameters
+API rule violation: list_type_missing,github.com/kubeflow/trainer/v2/pkg/apis/trainer/v1alpha1,OptimizationJobStatus,Conditions
+API rule violation: list_type_missing,github.com/kubeflow/trainer/v2/pkg/apis/trainer/v1alpha1,SearchSpace,List


akshaychitneni · 2026-06-01T23:41:52Z

+// +kubebuilder:validation:XValidation:rule="self.type != 'categorical' || has(self.list)",message="list must be provided when type is categorical"
+// +kubebuilder:validation:XValidation:rule="self.type == 'categorical' || (has(self.min) && has(self.max))",message="min and max must be provided for int or double types"
+type SearchSpace struct {
+	// +kubebuilder:validation:Enum=int;double;categorical
+	Type string `json:"type"` // e.g., int, double, categorical
+
+	Max string `json:"max,omitempty"`
+	Min string `json:"min,omitempty"`
+
+	// +optional


Could you look into above validations?

Addressed. Updated the CEL rules to check list sizes and added MinLength=1 / MinItems=1 markers to ensure empty strings and arrays are blocked.

+            "name": obj.get("name") if obj.get("name") is not None else '',
+            "value": obj.get("value") if obj.get("value") is not None else ''


akshaychitneni · 2026-06-01T22:58:11Z

+	// TrialTemplate acts as a generic wrapper for the underlying workload.
+	// Parameters are injected via native Kubernetes Environment Variables, replacing regex.
+	// +kubebuilder:pruning:PreserveUnknownFields
+	TrialTemplate runtime.RawExtension `json:"trialTemplate"`


Should we just use trainJobSpec here?

Since our MVP focuses on orchestrating TrainJobs, embedding the TrainJobSpec directly makes sense. But do you think this should be out long-term thought as well? I believe we discussed we want to keep it tightly coupled with TrainJob, but should we not consider keeping our option open for other types of Jobs?

akshaychitneni · 2026-06-02T00:02:04Z

+	// optimalParameters is a list of the hyperparameter assignments that won.
+	// +listType=atomic
+	// +optional
+	OptimalParameters []ParameterAssignment `json:"optimalParameters,omitempty"`


Should we just say parameters here? it should implicitly be optimal as it is part of besttrial

Makes sense, it was redundant.

akshaychitneni · 2026-06-02T00:12:14Z

Thanks for your work @aniket2405. Added a few comments on the api spec. please take a look

akshaychitneni · 2026-06-02T16:01:00Z

+// SearchSpace defines the type and exact boundaries for the algorithm to search.
+// +kubebuilder:validation:XValidation:rule="self.type != 'categorical' || (has(self.list) && size(self.list) > 0)",message="list must be provided and contain at least one item when type is categorical"
+// +kubebuilder:validation:XValidation:rule="self.type == 'categorical' || (has(self.min) && has(self.max) && self.min != ” && self.max != ”)",message="min and max must be provided and be non-empty for int or double types"
+type SearchSpace struct {


Explore concrete types that can be extended

google-oss-prow · 2026-06-29T14:54:34Z

@andreyvelich: GitHub didn't allow me to request PR reviews from the following users: mimowo.

Note that only kubeflow members and repo collaborators can review this PR, and authors cannot review their own PRs.

Details

In response to this:

Yeah, we can introduce the suspend fields in the later phases, once we integrate OptimizationJob with Kueue!

/cc @tenzen-y @kannon92 @mimowo @kaisoz

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andreyvelich · 2026-08-06T01:17:09Z

+	Direction ObjectiveDirection `json:"direction,omitempty"`
+}
+
+// +kubebuilder:validation:ExactlyOneOf=random;grid


Would be good to migrate to ExactlyOneOf in TrainingRuntime APIs too in the future PRs: https://github.com/kubeflow/trainer/blob/master/pkg/apis/trainer/v1alpha1/trainingruntime_types.go#L172

cc @tariq-hasan @Sridhar1030 @robert-bell @aniket2405

+1 , one doubt: since the current MLPolicy rule is <= 1 (zero policies allowed), wouldn't AtMostOneOf be the right fit here instead of ExactlyOneOf? Or do we want to tighten it?

Right.
ExactlyOneOf will be breaking change, given MLPolicy rule is <= 1. AtMostOneOf should be the right way forward imo.

Good point.

andreyvelich · 2026-08-06T01:25:03Z

+	// +kubebuilder:validation:MinLength=1
+	// +kubebuilder:validation:MaxLength=64
+	// +required
+	Value string `json:"value,omitempty"`


Good point, @aniket2405 let's define // +kubebuilder:validation:items:MaxLength=64 for categorical choices too.

Krishna-kg732 · 2026-08-06T09:58:41Z

Was reading through the status types and had a few thoughts, all in the "cheaper now than after v1alpha1" bucket. Push back if these were already considered.

status.result as a single struct — with multi-objective on the roadmap (#3799) that eventually becomes a Pareto set. Worth making it Results []Result now so the change stays additive?

Should Result also carry the objective value? Katib's OptimalTrial has Observation. Right now the winning score lives only on the TrainJob, and if that gets GC'd — which is the premise of #3744 — it's gone. Could reuse Metric from trainjob_types.go:593 so it costs no new schema.

Status *OptimizationJobStatus (L49) — any reason for the pointer? TrainJob uses a value with omitzero (trainjob_types.go:53), which I think is the more usual shape for a status subresource, but I may be missing context.

Smaller ones: no +kubebuilder:printcolumn (cf. trainjob_types.go:34), so kubectl get optimizationjobs won't show progress or outcome. And the condition type/reason constants — #3828 declares them in pkg/controller while TrainJob keeps them in the API package (trainjob_types.go:56); worth pulling them here? That'd also be a natural moment to reconcile the Running condition #3828 sets with the Created one KEP §7.4 describes, since the two currently disagree.

Probably just a doc nit: Objective.Metric says Defaults to "loss" (L111) but it's +required with no default marker — stale comment, or missing marker?

First two overlap with what @Sridhar1030 is proposing in #3856, cross-posting there so we don't end up with two status designs.

Signed-off-by: aniket2405 <aniketshaha2001@gmail.com>

andreyvelich · 2026-08-06T18:44:18Z

Thanks for the updates @aniket2405!
/lgtm
/assign @akshaychitneni @robert-bell @Sridhar1030

robert-bell

/lgtm

Thanks everyone! Excited to see this feature!

akshaychitneni · 2026-08-07T15:51:32Z

Great work @aniket2405
/lgtm

andreyvelich · 2026-08-07T16:08:16Z

Super excited to see this moving forward!
/lgtm
/approve

google-oss-prow · 2026-08-07T16:08:26Z

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Signed-off-by: aniket2405 <aniketshaha2001@gmail.com> (cherry picked from commit 0cd558c)

Copilot AI review requested due to automatic review settings May 26, 2026 13:55

google-oss-prow Bot requested review from akshaychitneni and jinchihe May 26, 2026 13:56

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aniket2405 changed the title ~~Introduce OptimizationJob API types under Trainer group~~ feat(api): introduce OptimizationJob CRD under Trainer Jun 10, 2026

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