use revision flag to simplify repo cloning

Dockerfile

@@ -3,7 +3,9 @@ FROM golang:1.24-alpine AS builder
 ARG TARGETOS
 ARG TARGETARCH
 
-RUN apk --no-cache add git openssh-client
+# '--repository' flag used to install latest git v 2.49
+# can be removed once alpine is updated to 3.22
+RUN apk --no-cache add git openssh-client --repository=https://dl-cdn.alpinelinux.org/alpine/edge/main
 
 WORKDIR /workspace
 # Copy the Go Modules manifests

pkg/mirror/repo_pool.go

@@ -303,12 +303,12 @@ func (rp *RepoPool) ObjectExists(ctx context.Context, remote, obj string) error
 }
 
 // Clone is wrapper around repositories Clone method
-func (rp *RepoPool) Clone(ctx context.Context, remote, dst, branch, pathspec string, rmGitDir bool) (string, error) {
+func (rp *RepoPool) Clone(ctx context.Context, remote, dst, branch string, pathspecs []string, rmGitDir bool) (string, error) {
 	repo, err := rp.Repository(remote)
 	if err != nil {
 		return "", err
 	}
-	return repo.Clone(ctx, dst, branch, pathspec, rmGitDir)
+	return repo.Clone(ctx, dst, branch, pathspecs, rmGitDir)
 }
 
 // MergeCommits is wrapper around repositories MergeCommits method

pkg/mirror/repository.go

@@ -302,7 +302,7 @@ func (r *Repository) ObjectExists(ctx context.Context, obj string) error {
 // if ref is commit hash then pathspec will be ignored.
 // if rmGitDir is true `.git` folder will be deleted after the clone.
 // if dst not empty all its contents will be removed.
-func (r *Repository) Clone(ctx context.Context, dst, ref, pathspec string, rmGitDir bool) (string, error) {
+func (r *Repository) Clone(ctx context.Context, dst, ref string, pathspecs []string, rmGitDir bool) (string, error) {
 	if ref == "" {
 		ref = "HEAD"
 	}
@@ -330,26 +330,17 @@ func (r *Repository) Clone(ctx context.Context, dst, ref, pathspec string, rmGit
 	r.lock.RLock()
 	defer r.lock.RUnlock()
 
-	if IsCommitHash(ref) {
-		return r.cloneByRef(ctx, dst, ref, pathspec, rmGitDir)
-	}
-	return r.cloneByBranch(ctx, dst, ref, pathspec, rmGitDir)
-}
-
-func (r *Repository) cloneByBranch(ctx context.Context, dst, branch, pathspec string, rmGitDir bool) (string, error) {
-	args := []string{"clone", "--no-checkout", "--single-branch"}
-	if branch != "HEAD" {
-		args = append(args, "-b", branch)
-	}
-	args = append(args, r.dir, dst)
-	// git clone --no-checkout --single-branch [-b <branch>] <remote> <dst>
+	// create a thin clone of a repository that only contains the history of the given revision
+	// git clone --no-checkout --revision <ref> <repo_src> <dst>
+	args := []string{"clone", "--no-checkout", "--revision", ref, r.dir, dst}
 	if _, err := runGitCommand(ctx, r.log, nil, "", args...); err != nil {
 		return "", err
 	}
 
-	args = []string{"checkout", branch}
-	if pathspec != "" {
-		args = append(args, "--", pathspec)
+	args = []string{"checkout", "HEAD"}
+	if len(pathspecs) > 0 {
+		args = append(args, "--")
+		args = append(args, pathspecs...)
 	}
 	// git checkout <branch> -- <pathspec>
 	if _, err := runGitCommand(ctx, r.log, nil, dst, args...); err != nil {
@@ -358,43 +349,7 @@ func (r *Repository) cloneByBranch(ctx context.Context, dst, branch, pathspec st
 
 	// get the hash of the repos HEAD
 	args = []string{"log", "--pretty=format:%H", "-n", "1", "HEAD"}
-	if pathspec != "" {
-		args = append(args, "--", pathspec)
-	}
-	// git log --pretty=format:%H -n 1 HEAD [-- <path>]
-	hash, err := runGitCommand(ctx, r.log, nil, dst, args...)
-	if err != nil {
-		return "", err
-	}
-
-	if rmGitDir {
-		if err := os.RemoveAll(filepath.Join(dst, ".git")); err != nil {
-			return "", fmt.Errorf("unable to delete git dir err:%w", err)
-		}
-	}
-
-	return hash, nil
-}
-
-func (r *Repository) cloneByRef(ctx context.Context, dst, ref, pathspec string, rmGitDir bool) (string, error) {
-	// git clone --no-checkout <remote> <dst>
-	if _, err := runGitCommand(ctx, r.log, nil, "", "clone", "--no-checkout", r.dir, dst); err != nil {
-		return "", err
-	}
-
-	args := []string{"reset", "--hard", ref}
-	// git reset --hard <ref>
-	if _, err := runGitCommand(ctx, r.log, nil, dst, args...); err != nil {
-		return "", err
-	}
-
-	// get the hash of the repos HEAD
-	args = []string{"log", "--pretty=format:%H", "-n", "1", "HEAD"}
-	if pathspec != "" {
-		args = append(args, "--", pathspec)
-	}
-
-	// git log --pretty=format:%H -n 1 HEAD [-- <path>]
+	// git log --pretty=format:%H -n 1 HEAD
 	hash, err := runGitCommand(ctx, r.log, nil, dst, args...)
 	if err != nil {
 		return "", err

pkg/mirror/z_e2e_race_test.go

@@ -93,7 +93,7 @@ func Test_mirror_detect_race_clone(t *testing.T) {
 				tempClone := mustTmpDir(t)
 				defer os.RemoveAll(tempClone)
 
-				if cloneSHA, err := repo.Clone(ctx, tempClone, testMainBranch, "", i%2 == 0); err != nil {
+				if cloneSHA, err := repo.Clone(ctx, tempClone, testMainBranch, nil, i%2 == 0); err != nil {
 					t.Fatalf("unexpected error %s", err)
 				} else {
 					if cloneSHA != fileSHA2 {