fix(gitlab): trigger PipelineRun only on label change

Before this patch pipeline was triggered on any merge request update,
regardless of what changed such as title, description or assigne changes

With the current change, pipeline will be triggered only when labels
are added or removed

Signed-off-by: PuneetPunamiya <[email protected]>

Author: PuneetPunamiya

pkg/provider/gitlab/detect.go

@@ -38,6 +38,14 @@ func (v *Provider) Detect(req *http.Request, payload string, logger *zap.Sugared
 
 	switch gitEvent := eventInt.(type) {
 	case *gitlab.MergeEvent:
+		// on a MR update, react only if OldRev is empty (no new commits pushed).
+		// If OldRev is empty, it's a metadata-only update (e.g., label changes).
+		if gitEvent.ObjectAttributes.Action == "update" && gitEvent.ObjectAttributes.OldRev == "" {
+			if !hasOnlyLabelsChanged(gitEvent) {
+				return setLoggerAndProceed(false, "this 'Merge Request' update event changes are not supported; cannot proceed", nil)
+			}
+		}
+
 		if provider.Valid(gitEvent.ObjectAttributes.Action, []string{"open", "reopen", "update"}) {
 			return setLoggerAndProceed(true, "", nil)
 		}
@@ -76,3 +84,27 @@ func (v *Provider) Detect(req *http.Request, payload string, logger *zap.Sugared
 		return setLoggerAndProceed(false, "", fmt.Errorf("gitlab: event \"%s\" is not supported", event))
 	}
 }
+
+// hasOnlyLabelsChanged checks if the only change in the merge request is to its labels.
+// This function ensures that other fields remain unchanged.
+func hasOnlyLabelsChanged(gitEvent *gitlab.MergeEvent) bool {
+	changes := gitEvent.Changes
+
+	labelsChanged := len(changes.Labels.Previous) > 0 || len(changes.Labels.Current) > 0
+
+	// Only Labels can change — everything else must be zero or nil
+	onlyUpdatedAtOrLabels := labelsChanged &&
+		changes.Assignees.Previous == nil && changes.Assignees.Current == nil &&
+		changes.Reviewers.Previous == nil && changes.Reviewers.Current == nil &&
+		changes.Description.Previous == "" && changes.Description.Current == "" &&
+		changes.MergeStatus.Previous == "" && changes.MergeStatus.Current == "" &&
+		changes.MilestoneID.Previous == 0 && changes.MilestoneID.Current == 0 &&
+		changes.SourceBranch.Previous == "" && changes.SourceBranch.Current == "" &&
+		changes.SourceProjectID.Previous == 0 && changes.SourceProjectID.Current == 0 &&
+		changes.StateID.Previous == 0 && changes.StateID.Current == 0 &&
+		changes.TargetBranch.Previous == "" && changes.TargetBranch.Current == "" &&
+		changes.TargetProjectID.Previous == 0 && changes.TargetProjectID.Current == 0 &&
+		changes.Title.Previous == "" && changes.Title.Current == ""
+
+	return onlyUpdatedAtOrLabels
+}

pkg/provider/gitlab/detect_test.go

@@ -72,6 +72,20 @@ func TestProvider_Detect(t *testing.T) {
 			isGL:       true,
 			processReq: true,
 		},
+		{
+			name:       "good/mergeRequest update Event with title",
+			event:      sample.MREventAsJSON("update", `"title": "test"`),
+			eventType:  gitlab.EventTypeMergeRequest,
+			isGL:       true,
+			processReq: false,
+		},
+		{
+			name:       "good/mergeRequest update Event with description",
+			event:      sample.MREventAsJSON("update", `"description": "test pac"`),
+			eventType:  gitlab.EventTypeMergeRequest,
+			isGL:       true,
+			processReq: false,
+		},
 		{
 			name:       "good/note event",
 			event:      sample.NoteEventAsJSON("abc"),

test/gitlab_merge_request_test.go

@@ -616,6 +616,80 @@ func TestGitlabDisableCommentsOnMR(t *testing.T) {
 	assert.Equal(t, 2, successCommentsPost)
 }
 
+func TestGitlabMergeRequestOnUpdateAtAndLabelChange(t *testing.T) {
+	targetNS := names.SimpleNameGenerator.RestrictLengthWithRandomSuffix("pac-e2e-ns")
+	ctx := context.Background()
+	runcnx, opts, glprovider, err := tgitlab.Setup(ctx)
+	assert.NilError(t, err)
+	ctx, err = cctx.GetControllerCtxInfo(ctx, runcnx)
+	assert.NilError(t, err)
+	runcnx.Clients.Log.Info("Testing with Gitlab")
+
+	projectinfo, resp, err := glprovider.Client().Projects.GetProject(opts.ProjectID, nil)
+	assert.NilError(t, err)
+	if resp != nil && resp.StatusCode == http.StatusNotFound {
+		t.Errorf("Repository %s not found in %s", opts.Organization, opts.Repo)
+	}
+
+	err = tgitlab.CreateCRD(ctx, projectinfo, runcnx, opts, targetNS, nil)
+	assert.NilError(t, err)
+
+	entries, err := payload.GetEntries(map[string]string{
+		".tekton/pipelinerun.yaml":       "testdata/pipelinerun.yaml",
+		".tekton/pipelinerun-clone.yaml": "testdata/pipelinerun-clone.yaml",
+	}, targetNS, projectinfo.DefaultBranch,
+		triggertype.PullRequest.String(), map[string]string{})
+	assert.NilError(t, err)
+
+	targetRefName := names.SimpleNameGenerator.RestrictLengthWithRandomSuffix("pac-e2e-test")
+
+	gitCloneURL, err := scm.MakeGitCloneURL(projectinfo.WebURL, opts.UserName, opts.Password)
+	assert.NilError(t, err)
+	commitTitle := "Committing files from test on " + targetRefName
+	scmOpts := &scm.Opts{
+		GitURL:        gitCloneURL,
+		CommitTitle:   commitTitle,
+		Log:           runcnx.Clients.Log,
+		WebURL:        projectinfo.WebURL,
+		TargetRefName: targetRefName,
+		BaseRefName:   projectinfo.DefaultBranch,
+	}
+	_ = scm.PushFilesToRefGit(t, scmOpts, entries)
+
+	runcnx.Clients.Log.Infof("Branch %s has been created and pushed with files", targetRefName)
+	mrTitle := "TestMergeRequest - " + targetRefName
+	mrID, err := tgitlab.CreateMR(glprovider.Client(), opts.ProjectID, targetRefName, projectinfo.DefaultBranch, mrTitle)
+	assert.NilError(t, err)
+	runcnx.Clients.Log.Infof("MergeRequest %s/-/merge_requests/%d has been created", projectinfo.WebURL, mrID)
+	defer tgitlab.TearDown(ctx, t, runcnx, glprovider, mrID, targetRefName, targetNS, opts.ProjectID)
+
+	sopt := twait.SuccessOpt{
+		Title:           commitTitle,
+		OnEvent:         "Merge Request",
+		TargetNS:        targetNS,
+		NumberofPRMatch: 2,
+		SHA:             "",
+	}
+	twait.Succeeded(ctx, t, runcnx, opts, sopt)
+	prsNew, err := runcnx.Clients.Tekton.TektonV1().PipelineRuns(targetNS).List(ctx, metav1.ListOptions{})
+	assert.NilError(t, err)
+	assert.Assert(t, len(prsNew.Items) == 2)
+
+	runcnx.Clients.Log.Infof("Changing Title on MergeRequest %s/-/merge_requests/%d", projectinfo.WebURL, mrID)
+	_, _, err = glprovider.Client().MergeRequests.UpdateMergeRequest(opts.ProjectID, mrID, &clientGitlab.UpdateMergeRequestOptions{
+		Title: clientGitlab.Ptr("test"),
+	})
+	assert.NilError(t, err)
+
+	// let's wait 10 secs and check every second that a PipelineRun is created or not.
+	for i := 0; i < 10; i++ {
+		prs, err := runcnx.Clients.Tekton.TektonV1().PipelineRuns(targetNS).List(ctx, metav1.ListOptions{})
+		assert.NilError(t, err)
+		assert.Assert(t, len(prs.Items) == 2)
+		time.Sleep(1 * time.Second)
+	}
+}
+
 // Local Variables:
 // compile-command: "go test -tags=e2e -v -run ^TestGitlabMergeRequest$"
 // End: