`rifle`: smart reviewer selection; alternative to `blunderbuss` by smg247 · Pull Request #787 · kubernetes-sigs/prow

smg247 · 2026-06-30T17:54:37Z

rifle acts as a, mutually exclusive, smart alternative plugin to blunderbuss. It replaces random reviewer selection with blame-based scoring that ranks OWNERS candidates by code contribution to changed files.

Add GetBlame to GitHub client (GraphQL blame API with Apps auth)
Score reviewers: (lines × 10) + (recency × 5) + owner bonus
Smart fallback: when not enough reviewers found, search broader OWNERS scope ranked by blame scores, fill remaining slots randomly

Implements: #780

kubernetes-prow · 2026-06-30T17:54:40Z

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

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smg247 · 2026-06-30T18:46:44Z

/hold going to make this into a new plugin so the old algorithm can be used by those that want it

linux-foundation-easycla · 2026-06-30T19:54:17Z

The committers listed above are authorized under a signed CLA.

✅ login: smg247 / name: Stephen Goeddel (76112a6, 8d69f90, 9172af1, ccdbac4)

Split the blunderbuss plugin into two mutually exclusive plugins in a shared review_assignment package: blunderbuss (random selection, original behavior) and rifle (blame-based scoring). This addresses review feedback that changing blunderbuss defaults would concentrate review load and work against the contributor-ladder model.

Move shared reviewer-selection infrastructure (interfaces, GetReviewers, FindReviewer, IsUserBusy, etc.) to pkg/reviewer/ as exported symbols. Restore pkg/plugins/blunderbuss/ for random selection and create pkg/plugins/rifle/ for blame-based selection as independent plugin packages that import from pkg/reviewer/.

…tyQuery

- Aggregate errors in handleStatus loop instead of returning only the last iteration's error. Also change early returns to continues so all matching PRs are processed. - Handle org/repo inheritance in validateMutuallyExclusivePlugins so configuring blunderbuss at org level and rifle at repo level (or vice versa) is caught, respecting ExcludedRepos.

smg247 · 2026-07-01T12:36:31Z

/hold cancel

- Fix alphabetical import ordering for rifle in checkconfig and plugin-imports files - Fix orphaned doc comment on GetBlame in fakegithub, add BlameData field so tests can configure blame responses - Add defaultRifleReviewerCount constant instead of reusing defaultBlunderbussReviewerCount - Rewrite TestReviewerScorer to call scoreReviewers instead of manually replicating scoring logic - Add MostRecentDate assertions to TestIntersectBlameWithChanges

stevekuznetsov · 2026-07-05T17:30:57Z

What's the additional GitHub API quota load of this approach?

smg247 · 2026-07-22T16:36:07Z

What's the additional GitHub API quota load of this approach?

Up to 20 additional REST API calls for GetBlame per PR (capped by maxBlameFiles). The IsUserBusy GraphQL calls are the same as blunderbuss and are cached via busyReviewers to avoid duplicates.

Keep in mind, utilizing rifle instead of blunderbuss is optional, and would not be recommended if API token budget is low.

I will look into adding docs to clarify this.

When all candidates are busy, the selector returns "" without modifying the candidate set, causing the loop condition to remain true forever. Break out of both reviewer selection loops when the selector returns empty to prevent this.

Document the rifle plugin as a blame-based alternative to blunderbuss for reviewer selection, including its algorithm, GitHub API quota impact, and fallback behavior.

kubernetes-prow · 2026-07-22T16:51:23Z

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: smg247

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kubernetes-prow Bot added the do-not-merge/work-in-progress Indicates that a PR should not merge because it is a work in progress. label Jun 30, 2026

smg247 marked this pull request as ready for review June 30, 2026 17:54

kubernetes-prow Bot removed the do-not-merge/work-in-progress Indicates that a PR should not merge because it is a work in progress. label Jun 30, 2026

kubernetes-prow Bot requested review from MadhavJivrajani and cjwagner June 30, 2026 17:54

kubernetes-prow Bot added the area/plugins Issues or PRs related to prow's plugins for the hook component label Jun 30, 2026

kubernetes-prow Bot requested review from Priyankasaggu11929 and stevekuznetsov June 30, 2026 17:54

kubernetes-prow Bot added the approved Indicates a PR has been approved by an approver from all required OWNERS files. label Jun 30, 2026

kubernetes-prow Bot requested a review from Prucek June 30, 2026 17:54

kubernetes-prow Bot added cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. size/XL Denotes a PR that changes 500-999 lines, ignoring generated files. labels Jun 30, 2026

smg247 force-pushed the smart-blunderbuss branch from b878716 to 1882614 Compare June 30, 2026 18:12

blunderbuss: smart reviewer selection using git blame scoring

9172af1

smg247 force-pushed the smart-blunderbuss branch from 1882614 to 9172af1 Compare June 30, 2026 18:37

kubernetes-prow Bot added size/XXL Denotes a PR that changes 1000+ lines, ignoring generated files. and removed size/XL Denotes a PR that changes 500-999 lines, ignoring generated files. labels Jun 30, 2026

kubernetes-prow Bot added do-not-merge/hold Indicates that a PR should not merge because someone has issued a /hold command. area/hook Issues or PRs related to prow's hook component labels Jun 30, 2026

kubernetes-prow Bot added cncf-cla: no Indicates the PR's author has not signed the CNCF CLA. and removed cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. labels Jun 30, 2026

smg247 added 3 commits July 1, 2026 07:13

Fix spelling lint: rename GithubAvailabilityQuery to GitHubAvailabili…

8d69f90

…tyQuery

smg247 force-pushed the smart-blunderbuss branch from 9a8fdc4 to 8d69f90 Compare July 1, 2026 11:16

kubernetes-prow Bot removed the cncf-cla: no Indicates the PR's author has not signed the CNCF CLA. label Jul 1, 2026

kubernetes-prow Bot added the cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. label Jul 1, 2026

kubernetes-prow Bot removed the do-not-merge/hold Indicates that a PR should not merge because someone has issued a /hold command. label Jul 1, 2026

smg247 changed the title ~~blunderbuss: smart reviewer selection using git blame scoring~~ rifle: smart reviewer; alternative to blunderbuss Jul 1, 2026

smg247 changed the title ~~rifle: smart reviewer; alternative to blunderbuss~~ rifle: smart reviewer selection; alternative to blunderbuss Jul 1, 2026

Prucek reviewed Jul 3, 2026

View reviewed changes

Comment thread pkg/plugins/rifle/rifle.go

smg247 added 2 commits July 22, 2026 12:43

Add rifle plugin documentation to reviewers and approvers doc

6bb540d

Document the rifle plugin as a blame-based alternative to blunderbuss for reviewer selection, including its algorithm, GitHub API quota impact, and fallback behavior.

kubernetes-prow Bot added the area/documentation Issues or PRs related to documentation label Jul 22, 2026

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`rifle`: smart reviewer selection; alternative to `blunderbuss` - #787

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