Allow gitaly create_repository to take a default branch argument

Currently when rails wants to ensure a default branch name, it will call
the Gitaly WriteRef RPC to manually change it. If this call happens in a
racy way eg: it gets called when another RPC is operating on the same
repository, it will fail. Rather than do this, the Gitaly
CreateRepository RPC has a default_branch parameter.

Allow rails callers to set this value. If it is not provided, then the
default branch in Gitaly will be used, which is main.

Gemfile

@@ -476,7 +476,7 @@ gem 'ssh_data', '~> 1.2'
 gem 'spamcheck', '~> 0.1.0'
 
 # Gitaly GRPC protocol definitions
-gem 'gitaly', '~> 14.9.0.pre.rc2'
+gem 'gitaly', '~> 14.9.0.pre.rc3'
 
 # KAS GRPC protocol definitions
 gem 'kas-grpc', '~> 0.0.2'

Gemfile.lock

@@ -455,7 +455,7 @@ GEM
       rails (>= 3.2.0)
     git (1.7.0)
       rchardet (~> 1.8)
-    gitaly (14.9.0.pre.rc2)
+    gitaly (14.9.0.pre.rc3)
       grpc (~> 1.0)
     github-markup (1.7.0)
     gitlab (4.16.1)
@@ -1475,7 +1475,7 @@ DEPENDENCIES
   gettext (~> 3.3)
   gettext_i18n_rails (~> 1.8.0)
   gettext_i18n_rails_js (~> 1.3)
-  gitaly (~> 14.9.0.pre.rc2)
+  gitaly (~> 14.9.0.pre.rc3)
   github-markup (~> 1.7.0)
   gitlab-chronic (~> 0.10.5)
   gitlab-dangerfiles (~> 2.10.2)

app/models/repository.rb

@@ -1085,10 +1085,10 @@ class Repository
     blob.data
   end
 
-  def create_if_not_exists
+  def create_if_not_exists(default_branch = nil)
     return if exists?
 
-    raw.create_repository
+    raw.create_repository(default_branch)
     after_create
 
     true

app/models/snippet.rb

@@ -367,7 +367,7 @@ class Snippet < ApplicationRecord
   def create_repository
     return if repository_exists? && snippet_repository
 
-    repository.create_if_not_exists
+    repository.create_if_not_exists(default_branch)
     track_snippet_repository(repository.storage)
   end
 

lib/gitlab/git/repository.rb

@@ -99,9 +99,9 @@ module Gitlab
         gitaly_repository_client.exists?
       end
 
-      def create_repository
+      def create_repository(default_branch = nil)
         wrapped_gitaly_errors do
-          gitaly_repository_client.create_repository
+          gitaly_repository_client.create_repository(default_branch)
         rescue GRPC::AlreadyExists => e
           raise RepositoryExists, e.message
         end

lib/gitlab/gitaly_client/repository_service.rb

@@ -107,8 +107,8 @@ module Gitlab
       end
       # rubocop: enable Metrics/ParameterLists
 
-      def create_repository
-        request = Gitaly::CreateRepositoryRequest.new(repository: @gitaly_repo)
+      def create_repository(default_branch = nil)
+        request = Gitaly::CreateRepositoryRequest.new(repository: @gitaly_repo, default_branch: default_branch)
         GitalyClient.call(@storage, :repository_service, :create_repository, request, timeout: GitalyClient.fast_timeout)
       end
 

spec/lib/gitlab/background_migration/backfill_snippet_repositories_spec.rb

@@ -78,6 +78,10 @@ RSpec.describe Gitlab::BackgroundMigration::BackfillSnippetRepositories, :migrat
     end
 
     shared_examples 'migration_bot user commits files' do
+      before do
+        allow(Gitlab::CurrentSettings).to receive(:default_branch_name).and_return('main')
+      end
+
       it do
         subject
 
@@ -89,6 +93,10 @@ RSpec.describe Gitlab::BackgroundMigration::BackfillSnippetRepositories, :migrat
     end
 
     shared_examples 'commits the file to the repository' do
+      before do
+        allow(Gitlab::CurrentSettings).to receive(:default_branch_name).and_return('main')
+      end
+
       context 'when author can update snippet and use git' do
         it 'creates the repository and commit the file' do
           subject
@@ -269,6 +277,10 @@ RSpec.describe Gitlab::BackgroundMigration::BackfillSnippetRepositories, :migrat
       let!(:snippet) { snippets.create!(id: 5, type: 'PersonalSnippet', author_id: other_user.id, file_name: file_name, content: content) }
       let(:ids) { [4, 5] }
 
+      before do
+        allow(Gitlab::CurrentSettings).to receive(:default_branch_name).and_return('main')
+      end
+
       after do
         raw_repository(snippet).remove
         raw_repository(invalid_snippet).remove

spec/lib/gitlab/gitaly_client/repository_service_spec.rb

@@ -218,6 +218,26 @@ RSpec.describe Gitlab::GitalyClient::RepositoryService do
     end
   end
 
+  describe '#create_repository' do
+    it 'sends a create_repository message without arguments' do
+      expect_any_instance_of(Gitaly::RepositoryService::Stub)
+        .to receive(:create_repository)
+        .with(gitaly_request_with_path(storage_name, relative_path).and(gitaly_request_with_params(default_branch: '')), kind_of(Hash))
+        .and_return(double)
+
+      client.create_repository
+    end
+
+    it 'sends a create_repository message with default branch' do
+      expect_any_instance_of(Gitaly::RepositoryService::Stub)
+        .to receive(:create_repository)
+        .with(gitaly_request_with_path(storage_name, relative_path).and(gitaly_request_with_params(default_branch: 'default-branch-name')), kind_of(Hash))
+        .and_return(double)
+
+      client.create_repository('default-branch-name')
+    end
+  end
+
   describe '#create_from_snapshot' do
     it 'sends a create_repository_from_snapshot message' do
       expect_any_instance_of(Gitaly::RepositoryService::Stub)

spec/models/repository_spec.rb

@@ -3062,6 +3062,14 @@ RSpec.describe Repository do
       repository.create_if_not_exists
     end
 
+    it 'creates a repository with a default branch name' do
+      default_branch_name = 'branch-a'
+      repository.create_if_not_exists(default_branch_name)
+      repository.create_file(user, 'file', 'content', message: 'initial commit', branch_name: default_branch_name)
+
+      expect(repository.root_ref).to eq(default_branch_name)
+    end
+
     context 'it does nothing if the repository already existed' do
       let(:project) { create(:project, :repository) }
 

spec/models/snippet_spec.rb

@@ -667,6 +667,16 @@ RSpec.describe Snippet do
       expect(snippet.repository.exists?).to be_truthy
     end
 
+    it 'sets the default branch' do
+      expect(snippet).to receive(:default_branch).and_return('default-branch-1')
+      expect(subject).to be_truthy
+
+      snippet.repository.create_file(snippet.author, 'file', 'content', message: 'initial commit', branch_name: 'default-branch-1')
+
+      expect(snippet.repository.exists?).to be_truthy
+      expect(snippet.repository.root_ref).to eq('default-branch-1')
+    end
+
     it 'tracks snippet repository' do
       expect do
         subject
@@ -677,6 +687,7 @@ RSpec.describe Snippet do
       expect(snippet).to receive(:repository_storage).and_return('picked')
       expect(snippet).to receive(:repository_exists?).and_return(false)
       expect(snippet.repository).to receive(:create_if_not_exists)
+      allow(snippet).to receive(:default_branch).and_return('picked')
 
       subject
 
@@ -899,22 +910,6 @@ RSpec.describe Snippet do
       end
     end
 
-    context 'when repository is empty' do
-      let(:snippet) { create(:snippet, :empty_repo) }
-
-      before do
-        allow(Gitlab::CurrentSettings).to receive(:default_branch_name).and_return(default_branch)
-      end
-
-      context 'when default branch in settings is different from "master"' do
-        let(:default_branch) { 'custom-branch' }
-
-        it 'changes the HEAD reference to the default branch' do
-          expect { subject }.to change { File.read(head_path).squish }.to("ref: refs/heads/#{default_branch}")
-        end
-      end
-    end
-
     context 'when repository is not empty' do
       let(:snippet) { create(:snippet, :empty_repo) }