fix(gh): fix re-run button on Pull Requests by chmouel · Pull Request #2597 · tektoncd/pipelines-as-code

chmouel · 2026-03-19T13:51:52Z

📝 Description of the Change

GitHub check_run and check_suite rerequests for fork PRs can have
a null head_branch and an empty pull_requests list. PAC was falling
back to treating these events as push events, causing the Re-run
button on PRs to have no effect.

When head_branch is null, fall back to looking up the associated PR
by commit SHA before deciding the event type. If a PR is found,
process as a PR rerequest. If not, return a clear error.

output.mp4

🔗 Linked Issue

Jira https://redhat.atlassian.net/browse/SRVKP-11161

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✅ Submitter Checklist

chmouel · 2026-03-19T14:42:14Z

/gemini review

Copilot

Pull request overview

This PR fixes GitHub check_run / check_suite “rerequested” handling for fork PRs where the webhook payload can have head_branch: null and an empty pull_requests list, by falling back to resolving the PR via commit SHA instead of misclassifying the event as a push.

Changes:

Update GitHub payload parsing to resolve PR rerequests by commit SHA when head_branch is missing.
Add unit tests covering the new SHA-resolution behavior and the error case when no PR is found.
Extend the GitHub GHE e2e rerequest test to exercise the null-head_branch check_run scenario; add a new JSON fixture.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 5 comments.

File	Description
`pkg/provider/github/parse_payload.go`	Adds SHA-based PR lookup fallback for rerequest events when `head_branch` is missing.
`pkg/provider/github/parse_payload_test.go`	Adds unit tests for null-`head_branch` rerequest behavior (success + failure).
`test/github_pullrequest_rerequest_test.go`	Adds an e2e scenario sending a `check_run` rerequest with null `head_branch` and empty PR list.
`test/fixtures/check_suite_rerequest_null_branch.json`	Adds a fixture representing a null-`head_branch` check_suite/check_run rerequest payload.

Comments suppressed due to low confidence (1)

pkg/provider/github/parse_payload.go:495

In the check_run rerequest fallback where this is treated as a push event, runevent.TriggerTarget is never set (unlike handleCheckSuites, which sets it to "push"). Downstream logic (e.g., changed-files fetching/switches on TriggerTarget) may treat an empty TriggerTarget as unknown and skip important behavior. Set runevent.TriggerTarget = triggertype.Push (or "push") alongside runevent.EventType = "push" for consistency.

		runevent.BaseBranch = runevent.HeadBranch
		runevent.BaseURL = runevent.HeadURL
		runevent.EventType = "push"
		// we allow the rerequest user here, not the push user, i guess it's
		// fine because you can't do a rereq without being a github owner?
		runevent.Sender = event.GetSender().GetLogin()
		v.userType = event.GetSender().GetType()
		return runevent, nil

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pkg/provider/github/parse_payload.go

test/fixtures/check_suite_rerequest_null_branch.json

chmouel · 2026-03-19T16:52:47Z

Review from Gemini Code

I've taken a deep look at this pull request. Here is my assessment:

The Problem:
GitHub's check_run and check_suite rerequested webhook payloads occasionally arrive with a null head_branch, particularly when triggered from the UI for pull requests without a full suite context. This caused the provider payload parser to either error out or incorrectly assume a push event when it shouldn't.

The Fix:
The introduced changes in pkg/provider/github/parse_payload.go correctly intercept cases where HeadBranch is empty and SHA is present. By falling back to getPullRequestsWithCommit, the code resolves the associated pull request directly via the GitHub API, reconstructing the missing context before continuing with v.getPullRequest(ctx, runevent). This is a clean and robust fallback.

Testing:

Unit Tests: Excellent additions in pkg/provider/github/parse_payload_test.go covering both check_run and check_suite scenarios where HeadBranch is null.
E2E Tests: A new test case in test/github_pullrequest_rerequest_test.go specifically verifies the "null head_branch" scenario dynamically, which is great for catching future regressions.
Test Fixtures: test/fixtures/check_suite_rerequest_null_branch.json correctly models the problematic webhook payload.

Conclusion:
The logic handles the edge case gracefully. The error handling is solid (failing fast if no PR is found). The tests are comprehensive. This looks good to merge. LGTM! 🚀

GitHub check_run and check_suite rerequests for fork PRs can have a null head_branch and an empty pull_requests list. PAC was falling back to treating these events as push events, causing the Re-run button on PRs to have no effect. When head_branch is null, fall back to looking up the associated PR by commit SHA before deciding the event type. If a PR is found, process as a PR rerequest. If not, return a clear error. Signed-off-by: Chmouel Boudjnah <chmouel@redhat.com> Assisted-by: Claude Sonnet 4.6 (via Claude Code) Signed-off-by: Chmouel Boudjnah <chmouel@redhat.com>

chmouel · 2026-03-20T15:17:29Z

/test linters

chmouel · 2026-03-20T15:18:07Z

/cancel linters

chmouel · 2026-03-20T15:23:11Z

/retest

zakisk · 2026-03-25T07:27:13Z

pkg/provider/github/parse_payload.go

 	if len(event.GetCheckSuite().PullRequests) == 0 {
+		// If head_branch is null, try to find a PR by SHA before assuming push
+		if runevent.HeadBranch == "" && runevent.SHA != "" {
+			prs, err := v.getPullRequestsWithCommit(ctx, runevent.SHA, runevent.Organization, runevent.Repository, false)


it might be possible that there are multiple pull requests associated with the commit, so can you please research more how we can figure out that first PR is the one on which re-request is clicked?

zakisk · 2026-03-25T07:29:39Z

pkg/provider/github/parse_payload.go

+				runevent.PullRequestNumber = prs[0].GetNumber()
+				runevent.TriggerTarget = triggertype.PullRequest
+				v.Logger.Infof("Rerun of all checks on PR %s/%s#%d has been requested (resolved from SHA)", runevent.Organization, runevent.Repository, runevent.PullRequestNumber)
+				return v.getPullRequest(ctx, runevent)


if we've fetched the PR from getPullRequestsWithCommit then we don't need to call getPullRequest again here because we have PR object and we have all the info. and also it will open the door for A Time-of-Check to Time-of-Use (TOCTOU) race condition attack.

zakisk · 2026-03-25T07:31:12Z

pkg/provider/github/parse_payload.go

 	if len(event.GetCheckRun().GetCheckSuite().PullRequests) == 0 {
+		// If head_branch is null, try to find a PR by SHA before assuming push
+		if runevent.HeadBranch == "" && runevent.SHA != "" {
+			prs, err := v.getPullRequestsWithCommit(ctx, runevent.SHA, runevent.Organization, runevent.Repository, false)


same concerns here and below

chmouel requested a review from Copilot March 19, 2026 14:42

Copilot AI reviewed Mar 19, 2026

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chmouel force-pushed the fix-gh-fix-re-run-button-on-pull-requests branch from 98e1889 to 7c8d958 Compare March 20, 2026 08:11

zakisk reviewed Mar 25, 2026

View reviewed changes

chmouel mentioned this pull request Mar 26, 2026

Automated release for tektoncd projects tektoncd/plumbing#58

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fix(gh): fix re-run button on Pull Requests#2597

fix(gh): fix re-run button on Pull Requests#2597
chmouel wants to merge 1 commit intotektoncd:mainfrom
chmouel:fix-gh-fix-re-run-button-on-pull-requests

chmouel commented Mar 19, 2026 •

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📝 Description of the Change

🔗 Linked Issue

🧪 Testing Strategy

🤖 AI Assistance

✅ Submitter Checklist

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Pull request overview

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chmouel commented Mar 19, 2026

Review from Gemini Code

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chmouel commented Mar 19, 2026 •

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