fix default branch detection when no ref passed (#437)

Author: SUSTAPLE117

analyze/analyze.go

@@ -175,7 +175,7 @@ func (a *Analyzer) AnalyzeOrg(ctx context.Context, org string, numberOfGoroutine
 				defer reposWg.Done()
 				repoNameWithOwner := repo.GetRepoIdentifier()
 				obs.OnRepoStarted(repoNameWithOwner)
-				repoKey, err := a.cloneRepo(ctx, repo.BuildGitURL(a.ScmClient.GetProviderBaseURL()), a.ScmClient.GetToken(), "HEAD")
+				repoKey, err := a.cloneRepo(ctx, repo.BuildGitURL(a.ScmClient.GetProviderBaseURL()), a.ScmClient.GetToken(), defaultBranchCloneRef(repo))
 				if err != nil {
 					log.Error().Err(err).Str("repo", repoNameWithOwner).Msg("failed to clone repo")
 					obs.OnRepoError(repoNameWithOwner, err)
@@ -450,7 +450,11 @@ func (a *Analyzer) AnalyzeRepo(ctx context.Context, repoString string, ref strin
 	log.Debug().Msgf("Starting repository analysis for: %s/%s on %s", org, repoName, provider)
 
 	obs.OnRepoStarted(repoString)
-	repoKey, err := a.cloneRepo(ctx, repo.BuildGitURL(a.ScmClient.GetProviderBaseURL()), a.ScmClient.GetToken(), ref)
+	cloneRef := ref
+	if ref == "" || ref == "HEAD" {
+		cloneRef = defaultBranchCloneRef(repo)
+	}
+	repoKey, err := a.cloneRepo(ctx, repo.BuildGitURL(a.ScmClient.GetProviderBaseURL()), a.ScmClient.GetToken(), cloneRef)
 	if err != nil {
 		obs.OnRepoError(repoString, err)
 		return nil, err
@@ -749,3 +753,15 @@ func (a *Analyzer) cloneRepo(ctx context.Context, gitURL string, token string, r
 	}
 	return key, nil
 }
+
+// defaultBranchCloneRef returns an explicit refs/heads/<branch> ref derived
+// from the SCM-provided default branch. Passing this to Clone avoids both
+// the ls-remote in the HEAD discovery path and the ls-remote in the bare-ref
+// resolver. Falls back to "HEAD" when the SCM didn't provide a default,
+// which routes through Clone's discovery path for correctness.
+func defaultBranchCloneRef(repo Repository) string {
+	if db := repo.GetDefaultBranch(); db != "" {
+		return "refs/heads/" + db
+	}
+	return "HEAD"
+}

providers/gitops/gitops.go

@@ -138,37 +138,47 @@ func (g *GitClient) Clone(ctx context.Context, clonePath string, url string, tok
 
 	switch {
 	case ref == "HEAD":
-		// Try "main" first (most common), then "master", then ls-remote as fallback
-		for _, branch := range []string{"main", "master"} {
+		// Discover the actual default branch via ls-remote HEAD symref.
+		// Doing this first (rather than fast-pathing to main/master) avoids
+		// analyzing the wrong branch on repositories whose default is not main.
+		discovered := discoverDefaultBranch(repo, token)
+		if discovered != "" {
 			fetchOpts.RefSpecs = []config.RefSpec{
-				config.RefSpec(fmt.Sprintf("+refs/heads/%s:refs/remotes/origin/%s", branch, branch)),
+				config.RefSpec(fmt.Sprintf("+refs/heads/%s:refs/remotes/origin/%s", discovered, discovered)),
 			}
 			err = repo.FetchContext(ctx, fetchOpts)
 			if err == nil {
-				defaultBranch = branch
-				resolved.localRef = plumbing.ReferenceName("refs/remotes/origin/" + branch)
-				break
-			}
-			if classifyFetchError(err) != nil && !strings.Contains(err.Error(), "couldn't find remote ref") {
-				return classifyFetchError(err)
+				defaultBranch = discovered
+				resolved.localRef = plumbing.ReferenceName("refs/remotes/origin/" + discovered)
+			} else if cerr := classifyFetchError(err); cerr != nil && !strings.Contains(err.Error(), "couldn't find remote ref") {
+				return cerr
 			}
 		}
 		if defaultBranch == "" {
-			// Neither main nor master — ls-remote to find actual default
-			discovered := discoverDefaultBranchFromURL(url, token)
-			if discovered != "" {
+			// Discovery failed (e.g. server didn't advertise HEAD, or fetch of
+			// discovered branch failed). Try common defaults before falling
+			// back to fetching all branches.
+			for _, branch := range []string{"main", "master"} {
 				fetchOpts.RefSpecs = []config.RefSpec{
-					config.RefSpec(fmt.Sprintf("+refs/heads/%s:refs/remotes/origin/%s", discovered, discovered)),
+					config.RefSpec(fmt.Sprintf("+refs/heads/%s:refs/remotes/origin/%s", branch, branch)),
+				}
+				err = repo.FetchContext(ctx, fetchOpts)
+				if err == nil {
+					defaultBranch = branch
+					resolved.localRef = plumbing.ReferenceName("refs/remotes/origin/" + branch)
+					break
+				}
+				if cerr := classifyFetchError(err); cerr != nil && !strings.Contains(err.Error(), "couldn't find remote ref") {
+					return cerr
 				}
-				resolved.localRef = plumbing.ReferenceName("refs/remotes/origin/" + discovered)
-			} else {
-				fetchOpts.RefSpecs = []config.RefSpec{config.RefSpec("+refs/heads/*:refs/remotes/origin/*")}
 			}
+		}
+		if defaultBranch == "" {
+			fetchOpts.RefSpecs = []config.RefSpec{config.RefSpec("+refs/heads/*:refs/remotes/origin/*")}
 			err = repo.FetchContext(ctx, fetchOpts)
 			if err := classifyFetchError(err); err != nil {
 				return err
 			}
-			defaultBranch = discovered
 		}
 	default:
 		resolved, err = resolveRemoteRef(repo, url, token, ref)
@@ -772,20 +782,10 @@ func peelToCommit(store storer.EncodedObjectStorer, hash plumbing.Hash) (plumbin
 	}
 }
 
-// looksLikeSHA returns true if s looks like a full-length git commit SHA.
-// discoverDefaultBranch uses remote.List to find the HEAD symref target.
-// Returns empty string if it can't be determined.
-// discoverDefaultBranchFromURL does a lightweight ls-remote to find the HEAD symref.
-func discoverDefaultBranchFromURL(url string, token string) string {
-	store := memory.NewStorage()
-	repo, err := gogit.Init(store, nil)
-	if err != nil {
-		return ""
-	}
-	_, err = repo.CreateRemote(&config.RemoteConfig{Name: "origin", URLs: []string{url}})
-	if err != nil {
-		return ""
-	}
+// discoverDefaultBranch performs a lightweight ls-remote on the repo's origin
+// remote and returns the branch name that HEAD points to. Returns "" when the
+// server doesn't advertise a HEAD symref or the listing fails.
+func discoverDefaultBranch(repo *gogit.Repository, token string) string {
 	remote, err := repo.Remote("origin")
 	if err != nil {
 		return ""

providers/gitops/gitops_test.go

@@ -157,6 +157,34 @@ func TestClassifyFetchError(t *testing.T) {
 	assert.Error(t, err)
 }
 
+// TestDiscoverDefaultBranchPrefersRemoteHEAD is the regression for #436:
+// when a repo has both `main` and another branch, and HEAD points to the
+// other branch, discoverDefaultBranch must report the HEAD-pointed branch
+// rather than fast-pathing to "main". Clone() consults this helper before
+// falling back to "main"/"master", so getting this right ensures HEAD
+// analysis follows the actual default branch.
+func TestDiscoverDefaultBranchPrefersRemoteHEAD(t *testing.T) {
+	dir := t.TempDir()
+	remote, err := gogit.PlainInit(dir, false)
+	require.NoError(t, err)
+
+	writeRepoFile(t, dir, "action.yml", "name: initial\n")
+	initialCommit := commitAll(t, remote, "initial commit")
+
+	require.NoError(t, remote.Storer.SetReference(
+		plumbing.NewHashReference(plumbing.ReferenceName("refs/heads/main"), initialCommit),
+	))
+	require.NoError(t, remote.Storer.SetReference(
+		plumbing.NewHashReference(plumbing.ReferenceName("refs/heads/zip-zip"), initialCommit),
+	))
+	require.NoError(t, remote.Storer.SetReference(
+		plumbing.NewSymbolicReference(plumbing.HEAD, plumbing.ReferenceName("refs/heads/zip-zip")),
+	))
+
+	client := createTestClientRepo(t, dir)
+	assert.Equal(t, "zip-zip", discoverDefaultBranch(client, ""))
+}
+
 func TestResolveRemoteRefBareTagPrefersTag(t *testing.T) {
 	remotePath, _ := createTestRemoteRepo(t)
 	repo := createTestClientRepo(t, remotePath)