Export mutateSparkPodOption and its implementations

[everpeace]

Purpose of this PR

Proposed changes:

• Export mutateSparkPodOption, which was originally defined in internal/webhook, in pkg/webhook so that so that external tools(e.g. kueue) can re-use the mutation logic

Change Category

• Bugfix (non-breaking change which fixes an issue)
• Feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that could affect existing functionality)
• Documentation update

Rationale

Spark operator integration in Kueue should calculate spark driver/executor pods' shape(resource requests/limits, volume, etc.) so that kueue correctly decide the workload should be admitted or not.

Thus, mutateSparkPodOption logics are needed to re-use in Kueue integration.

ref: kubernetes-sigs/kueue#7268 (comment)

Checklist

• I have conducted a self-review of my own code.
• I have updated documentation accordingly.
• I have added tests that prove my changes are effective or that my feature works.
• Existing unit tests pass locally with my changes.

Additional Notes

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[Copilot]

Pull request overview

This PR moves the Spark pod mutation option type and its mutation implementations out of internal/webhook into pkg/webhook, so external integrations (e.g., Kueue) can reuse the same driver/executor pod shaping logic as the operator’s mutating webhook.

Changes:

• Added a new public pkg/webhook package file that contains MutateSparkPodOption and the Spark pod mutation functions.
• Refactored internal/webhook Spark pod defaulter to call the exported mutation functions from pkg/webhook.

Reviewed changes

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

File	Description
pkg/webhook/mutate_spark_option.go	Introduces exported pod mutation option type and exported mutation/helper functions for reuse by external tools.
internal/webhook/sparkpod_defaulter.go	Switches the internal webhook to use the exported mutation options from pkg/webhook.

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[kannon92]

Since we are exporting mutate_spark_operaton, we should make sure to have unit tests.

[everpeace]

Since we are exporting mutate_spark_operaton, we should make sure to have unit tests.

Actually, these methods are well tested here: https://github.com/kubeflow/spark-operator/blob/master/internal/webhook/sparkpod_defaulter_test.go

I will move the tests into pkg/webhook package from internal/webhook.