Add dependency policy event: DependencyPolicyConflict

[Kexin2000]

What type of PR is this?

/kind feature

What this PR does / why we need it:

Adds observability for dependency policy conflicts. When multiple independent resources define divergent policies on the same dependent resource, Karmada now emits a single warning event to surface the behavior.

Which issue(s) this PR fixes:
Fixes #6000
Part of #6803

Special notes for your reviewer:

• Adds the following event reason in pkg/events/events.go:

  • DependencyPolicyConflict: emitted when a dependency policy conflict is detected.

• Updates createOrUpdateAttachedBinding in pkg/dependenciesdistributor/dependencies_distributor.go to:

  • Treat RBs with Spec.Placement == nil as dependency-generated:
    • Detect conflicts and emit a Warning event (DependencyPolicyConflict).
  • For policy-owned RBs (Spec.Placement != nil), leave Spec.ConflictResolution unchanged

Does this PR introduce a user-facing change?:

`karmada-controller-manager`: Added a new Warning event `DependencyPolicyConflict` to surface when dependency policy have conflicts.

[karmada-bot]

Welcome @Kexin2000! It looks like this is your first PR to karmada-io/karmada 🎉

[gemini-code-assist]

Summary of Changes

Hello @Kexin2000, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly improves the stability and predictability of resource management in Karmada by addressing issues related to multi-path distribution. It enhances the system's ability to communicate dependency policy states through new event reasons and rectifies a behavioral flaw where dependency mechanisms could inadvertently override explicitly defined resource binding configurations. These changes collectively aim to prevent field flapping and ensure that explicit policies are respected, leading to more robust and understandable resource propagation.

Highlights

• Enhanced Observability: Introduced new event reasons (DependencyPolicyConflict, DependencyPolicyAggregated, DependencyOverriddenByExplicitPolicy) to provide better visibility into dependency policy conflicts and aggregation within Karmada's dependency distribution mechanism.
• Behavioral Fix for ResourceBindings: Prevented the dependency controller from overwriting ConflictResolution and PreserveResourcesOnDeletion fields on ResourceBindings (RBs) that are explicitly governed by PropagationPolicy or ClusterPropagationPolicy, ensuring explicit policies take precedence.

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[Copilot]

Pull Request Overview

This PR enhances the dependency distribution mechanism in Karmada by adding observability events and preventing field overrides on explicitly governed ResourceBindings. The changes address issues with multi-path distribution causing field flapping and unpredictable behavior.

• Adds three new event reasons for better visibility into dependency policy conflicts and aggregation
• Modifies dependency controller to respect explicit policy ownership of ResourceBindings
• Prevents overwriting of ConflictResolution and PreserveResourcesOnDeletion fields when ResourceBindings are governed by PropagationPolicy or ClusterPropagationPolicy

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
pkg/events/events.go	Adds three new event reason constants for dependency policy handling
pkg/dependenciesdistributor/dependencies_distributor.go	Updates binding update logic to conditionally set fields and emit warning events

---

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[gemini-code-assist]

Code Review

This pull request introduces new events for dependency policies and prevents the dependency distributor from overwriting fields on ResourceBindings that are managed by an explicit policy. The changes are logical and address the intended issue. However, I've found one issue with the implementation of the new warning event, which could lead to excessive event logging. My review includes a suggestion to refine the condition for firing this event to make it more meaningful and less noisy.

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

❌ Patch coverage is 85.48387% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 46.28%. Comparing base (f3c4376) to head (e6922db).
⚠️ Report is 66 commits behind head on master.

Files with missing lines	Patch %	Lines
...ependenciesdistributor/dependencies_distributor.go	66.66%	2 Missing and 3 partials ⚠️
pkg/dependenciesdistributor/policy_utils.go	91.48%	2 Missing and 2 partials ⚠️
❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6795      +/-   ##
==========================================
+ Coverage   45.82%   46.28%   +0.46%     
==========================================
  Files         690      693       +3     
  Lines       57242    47249    -9993     
==========================================
- Hits        26231    21871    -4360     
+ Misses      29384    23721    -5663     
- Partials     1627     1657      +30     

Flag	Coverage Δ
unittests	46.28% <85.48%> (+0.46%)	⬆️

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[XiShanYongYe-Chang]

If the PR is ready, remember to cc me.

[Kexin2000]

Hi @XiShanYongYe-Chang, the PR is now ready for review. Please take a look when you are free. 😃 This PR only adds the new event. The changes to the conflict field aggregation logic are in a separate PR #6796.

[XiShanYongYe-Chang]

Hi @XiShanYongYe-Chang, the PR is now ready for review. Please take a look when you are free. 😃 This PR only adds the new event. The changes to the conflict field aggregation logic are in a separate PR #6796.

Good.

/assign

[gemini-code-assist]

Code Review

This pull request introduces a new event, DependencyPolicyConflict, to enhance observability for dependency policy conflicts in Karmada. It modifies the createOrUpdateAttachedBinding function to detect conflicts in ConflictResolution and PreserveResourcesOnDeletion settings, emitting a warning event when discrepancies are found. Additionally, the pull request includes corresponding unit tests to validate the new functionality. No style guide was provided, so the review focuses on correctness and code clarity.

[XiShanYongYe-Chang]

Thanks~

[Kexin2000]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces a new DependencyPolicyConflict event to improve observability when multiple resources define conflicting dependency policies. The implementation correctly identifies conflicts in ConflictResolution and PreserveResourcesOnDeletion for dependency-generated resource bindings and emits a warning event. The changes are well-tested. I've provided a few suggestions to improve code quality, performance, and conciseness.

[Kexin2000]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces a new DependencyPolicyConflict event to provide observability into conflicting dependency policies. The implementation adds new logic to detect conflicts in ConflictResolution and PreserveResourcesOnDeletion settings from different ResourceBindings. The changes are well-tested with a new unit test to verify event emission.

My review focuses on improving the efficiency of the new conflict detection logic and adhering to best practices for context propagation. I've suggested merging the two conflict detection functions into one to reduce redundant API calls. I also pointed out the use of context.TODO() and a minor issue with a copyright year.

[XiShanYongYe-Chang]

Thanks~
/lgtm
/cc @RainbowMango

[XiShanYongYe-Chang]

/lgtm

[RainbowMango]

/assign

[RainbowMango]

/approve

[karmada-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: RainbowMango

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