use lightweight checkout (#179)

gitops/git/git.go

@@ -36,11 +36,12 @@ func Clone(repo, dir, mirrorDir, primaryBranch, gitopsPath string) (*Repo, error
 	if err := os.RemoveAll(dir); err != nil {
 		return nil, fmt.Errorf("Unable to clone repo: %w", err)
 	}
+	args := []string{"clone", "--no-checkout", "--single-branch", "--branch", primaryBranch, "--filter=blob:none", "--no-tags"}
 	if mirrorDir != "" {
-		exec.Mustex("", "git", "clone", "-n", "--reference", mirrorDir, repo, dir)
-	} else {
-		exec.Mustex("", "git", "clone", "-n", repo, dir)
+		args = append(args, "--reference", mirrorDir)
 	}
+	args = append(args, repo, dir)
+	exec.Mustex("", "git", args...)
 	exec.Mustex(dir, "git", "config", "--local", "core.sparsecheckout", "true")
 	genPath := fmt.Sprintf("%s/\n", gitopsPath)
 	if err := ioutil.WriteFile(filepath.Join(dir, ".git/info/sparse-checkout"), []byte(genPath), 0644); err != nil {
@@ -65,6 +66,12 @@ func (r *Repo) Clean() error {
 	return os.RemoveAll(r.Dir)
 }
 
+// Fetch branches from the remote repository based on a specified pattern.
+func (r *Repo) Fetch(pattern string) {
+	refSpec := fmt.Sprintf("+refs/heads/%s:refs/remotes/origin/%s", pattern, pattern)
+	exec.Mustex(r.Dir, "git", "fetch", "--force", "--filter=blob:none", "--no-tags", "origin", refSpec)
+}
+
 // SwitchToBranch switch the repo to specified branch and checkout primaryBranch files over it.
 // if branch does not exist it will be created
 func (r *Repo) SwitchToBranch(branch, primaryBranch string) (new bool) {

gitops/prer/create_gitops_prs.go

@@ -65,6 +65,7 @@ var (
 	prTitle                = flag.String("gitops_pr_title", "", "a title for deployment PR")
 	branchName             = flag.String("branch_name", "unknown", "Branch name to use in commit message")
 	gitCommit              = flag.String("git_commit", "unknown", "Git commit to use in commit message")
+	deploymentBranchPrefix = flag.String("deployment_branch_prefix", "deploy/", "the prefix to add to all deployment branch names")
 	deploymentBranchSuffix = flag.String("deployment_branch_suffix", "", "suffix to add to all deployment branch names")
 	gitHost                = flag.String("git_server", "bitbucket", "the git server api to use. 'bitbucket', 'github' or 'gitlab'")
 	gitopsKind             SliceFlags
@@ -156,13 +157,14 @@ func main() {
 	if err != nil {
 		log.Fatalf("Unable to clone repo: %v", err)
 	}
+	workdir.Fetch(*deploymentBranchPrefix + "*")
 
 	var updatedGitopsTargets []string
 	var updatedGitopsBranches []string
 
 	for train, targets := range releaseTrains {
 		log.Println("train", train)
-		branch := fmt.Sprintf("deploy/%s%s", train, *deploymentBranchSuffix)
+		branch := *deploymentBranchPrefix + train + *deploymentBranchSuffix
 		newBranch := workdir.SwitchToBranch(branch, *prInto)
 		if !newBranch {
 			// Find if we need to recreate the branch because target was deleted