feat: add HostnamePolicy field to CollaSetSpec

[ColdsteelRail]

Add HostnamePolicyType and HostnamePolicyPodName constant to support configuring pod hostname based on pod name in CollaSet.

1. Does this PR affect any open issues?(Y/N) and add issue references (e.g. "fix #123", "re #123".):

• N
• Y

2. What is the scope of this PR (e.g. component or file name):

3. Provide a description of the PR(e.g. more details, effects, motivations or doc link):

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Other

4. Are there any breaking changes?(Y/N) and describe the breaking changes(e.g. more details, motivations or doc link):

• N
• Y

5. Are there test cases for these changes?(Y/N) select and add more details, references or doc links:

• Unit test
• Integration test
• Benchmark (add benchmark stats below)
• Manual test (add detailed scripts or steps below)
• Other

6. Release note

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[Copilot]

Pull request overview

Adds a new HostnamePolicy field (with constant HostnamePolicyPodName) to CollaSetSpec so a CollaSet can declare that each pod's spec.hostname should match its pod name. The change is type-only at the moment — the Go change is limited to API definitions, and the CRD YAMLs reflect both the new field and a large amount of unrelated controller-gen/schema regeneration.

Changes:

• Introduce HostnamePolicyType and HostnamePolicyPodName constant in apps/v1alpha1/collaset_types.go, and add HostnamePolicy field to CollaSetSpec.
• Regenerate apps.kusionstack.io_collasets.yaml to include the new hostnamePolicy schema (plus large unrelated upstream schema updates for PVC templates).
• Unrelated CRD schema regenerations in apps.kusionstack.io_poddecorations.yaml and rollout.kusionstack.io_backendroutings.yaml (gRPC probes, resizePolicy, claims, dataSourceRef.namespace, description text refreshes, etc.).

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 2 comments.

File	Description
apps/v1alpha1/collaset_types.go	Adds the HostnamePolicyType enum type, HostnamePolicyPodName constant, and the new HostnamePolicy field on CollaSetSpec. No consumer logic is added.
config/crd/apps/apps.kusionstack.io_collasets.yaml	Adds the hostnamePolicy property to the CRD; also includes unrelated PVC template schema regeneration (claims, dataSourceRef.namespace, resizeStatus, allocatedResources, etc.).
config/crd/apps/apps.kusionstack.io_poddecorations.yaml	Unrelated CRD regeneration: adds gRPC probe, resizePolicy, resources.claims, dataSourceRef.namespace, and description refreshes throughout the pod template schema.
config/crd/rollout/rollout.kusionstack.io_backendroutings.yaml	Unrelated CRD regeneration: reformats the Condition description to a single-line YAML string.

Comments suppressed due to low confidence (2)

apps/v1alpha1/collaset_types.go:140

• The new HostnamePolicy field is declared in the API type and exposed in the CRD, but a search of the repository shows no consumer of this field anywhere. There is no controller logic that reads HostnamePolicy and sets pod.Spec.Hostname to the pod name, so setting hostnamePolicy: PodName on a CollaSet will currently have no effect. As-shipped, this is a non-functional API addition. The implementation that actually applies the hostname to created pods (and any unit/e2e tests covering it) needs to be included before this field is exposed to users.

	// HostnamePolicy indicates how the pod's hostname is determined.
	// When set to "PodName", the pod's spec.hostname will be set to the pod name.
	// This requires NamingStrategy.PodNamingSuffixPolicy to be PersistentSequence.
	// +optional
	HostnamePolicy HostnamePolicyType `json:"hostnamePolicy,omitempty"`

apps/v1alpha1/collaset_types.go:140

• The doc comment states "This requires NamingStrategy.PodNamingSuffixPolicy to be PersistentSequence", but there is no validation enforcing this precondition (no webhook check, no CEL rule on the CRD field, no controller-side guard). A user can set hostnamePolicy: PodName together with the default Random suffix policy (or with no NamingStrategy at all), in which case pod names are generated server-side and the stated invariant is silently violated. Add an admission/validation check that rejects this combination, or document the behavior when the precondition is not met.

	// HostnamePolicy indicates how the pod's hostname is determined.
	// When set to "PodName", the pod's spec.hostname will be set to the pod name.
	// This requires NamingStrategy.PodNamingSuffixPolicy to be PersistentSequence.
	// +optional
	HostnamePolicy HostnamePolicyType `json:"hostnamePolicy,omitempty"`

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