Don't synchronize default branch for pull mirrors

Revert to the previous behavior for pull mirrors where the
default branch is not synchronized. Not everyone wants to
mirror the default branch of the upstream repository.

ee/app/services/projects/update_mirror_service.rb

@@ -17,7 +17,6 @@ module Projects
       end
 
       update_branches
-      update_root_ref
 
       success
     rescue Gitlab::Shell::Error, UpdateError => e
@@ -61,22 +60,6 @@ module Projects
       end
     end
 
-    # Update the default branch querying the remote to determine its HEAD
-    def update_root_ref
-      # Fetch remote default branch doesn't work with SSH mirrors:
-      # https://gitlab.com/gitlab-org/gitaly/issues/1363
-      return if ssh_mirror?
-
-      project.update_root_ref(::Repository::MIRROR_REMOTE)
-    end
-
-    def ssh_mirror?
-      uri = Addressable::URI.parse(project.import_url)
-      uri.scheme.present? && uri.scheme == 'ssh'
-    rescue Addressable::URI::InvalidURIError
-      false
-    end
-
     def update_tags(&block)
       old_tags = repository_tags_with_target.each_with_object({}) { |tag, tags| tags[tag.name] = tag }
 

ee/changelogs/unreleased/8108-disable-default-branch-synchronization-for-pull-mirrors.yml

+---
+title: Does not synchronize default branch for pull mirrors
+merge_request: 8138
+author:
+type: changed

ee/spec/services/projects/update_mirror_service_spec.rb

@@ -23,8 +23,6 @@ describe Projects::UpdateMirrorService do
     end
 
     it "fetches the upstream repository" do
-      stub_find_remote_root_ref(project)
-
       expect(project).to receive(:fetch_mirror)
 
       service.execute
@@ -32,7 +30,6 @@ describe Projects::UpdateMirrorService do
 
     it 'rescues exceptions from Repository#ff_merge' do
       stub_fetch_mirror(project)
-      stub_find_remote_root_ref(project)
 
       expect(project.repository).to receive(:ff_merge).and_raise(Gitlab::Git::PreReceiveError)
 
@@ -41,7 +38,6 @@ describe Projects::UpdateMirrorService do
 
     it "returns success when updated succeeds" do
       stub_fetch_mirror(project)
-      stub_find_remote_root_ref(project)
 
       result = service.execute
 
@@ -51,7 +47,6 @@ describe Projects::UpdateMirrorService do
     context "updating tags" do
       it "creates new tags" do
         stub_fetch_mirror(project)
-        stub_find_remote_root_ref(project)
 
         service.execute
 
@@ -60,7 +55,6 @@ describe Projects::UpdateMirrorService do
 
       it "only invokes GitTagPushService for tags pointing to commits" do
         stub_fetch_mirror(project)
-        stub_find_remote_root_ref(project)
 
         expect(GitTagPushService).to receive(:new)
           .with(project, project.owner, hash_including(ref: 'refs/tags/new-tag'))
@@ -84,7 +78,6 @@ describe Projects::UpdateMirrorService do
           project.reload
 
           stub_fetch_mirror(project)
-          stub_find_remote_root_ref(project)
 
           service.execute
 
@@ -93,7 +86,6 @@ describe Projects::UpdateMirrorService do
 
         it 'does not create an unprotected branch' do
           stub_fetch_mirror(project)
-          stub_find_remote_root_ref(project)
 
           service.execute
 
@@ -105,7 +97,6 @@ describe Projects::UpdateMirrorService do
           project.reload
 
           stub_fetch_mirror(project)
-          stub_find_remote_root_ref(project)
 
           service.execute
 
@@ -115,7 +106,6 @@ describe Projects::UpdateMirrorService do
 
         it "does not update unprotected branches" do
           stub_fetch_mirror(project)
-          stub_find_remote_root_ref(project)
 
           service.execute
 
@@ -126,7 +116,6 @@ describe Projects::UpdateMirrorService do
 
       it "creates new branches" do
         stub_fetch_mirror(project)
-        stub_find_remote_root_ref(project)
 
         service.execute
 
@@ -135,7 +124,6 @@ describe Projects::UpdateMirrorService do
 
       it "updates existing branches" do
         stub_fetch_mirror(project)
-        stub_find_remote_root_ref(project)
 
         service.execute
 
@@ -146,7 +134,6 @@ describe Projects::UpdateMirrorService do
       context 'with diverged branches' do
         before do
           stub_fetch_mirror(project)
-          stub_find_remote_root_ref(project)
         end
 
         context 'when mirror_overwrites_diverged_branches is true' do
@@ -187,7 +174,6 @@ describe Projects::UpdateMirrorService do
         it 'does not add a default master branch' do
           project    = create(:project_empty_repo, :mirror, import_url: Project::UNKNOWN_IMPORT_URL)
           repository = project.repository
-          stub_find_remote_root_ref(project)
 
           allow(project).to receive(:fetch_mirror) { create_file(repository) }
           expect(CreateBranchService).not_to receive(:create_master_branch)
@@ -209,35 +195,8 @@ describe Projects::UpdateMirrorService do
       end
     end
 
-    context 'synchronize the default branch' do
-      it 'updates the default branch when HEAD has changed' do
-        stub_fetch_mirror(project)
-        stub_find_remote_root_ref(project, ref: 'new-branch')
-
-        expect { service.execute }.to change { project.default_branch }.from('master').to('new-branch')
-      end
-
-      it 'does not update the default branch when HEAD does not change' do
-        stub_fetch_mirror(project)
-        stub_find_remote_root_ref(project, ref: 'master')
-
-        expect { service.execute }.not_to change { project.default_branch }
-      end
-
-      it 'does not update the default branch with SSH mirrors' do
-        project.update(import_url: 'ssh://git@example.com/foo/bar.git')
-
-        expect(project.repository)
-          .not_to receive(:find_remote_root_ref)
-          .with('upstream')
-
-        service.execute
-      end
-    end
-
     it "fails when the mirror user doesn't have access" do
       stub_fetch_mirror(project)
-      stub_find_remote_root_ref(project)
 
       result = described_class.new(project, create(:user)).execute
 
@@ -260,13 +219,6 @@ describe Projects::UpdateMirrorService do
     end
   end
 
-  def stub_find_remote_root_ref(project, remote: 'upstream', ref: 'master')
-    allow(project.repository)
-      .to receive(:find_remote_root_ref)
-      .with(remote)
-      .and_return(ref)
-  end
-
   def stub_fetch_mirror(project, repository: project.repository)
     allow(project).to receive(:fetch_mirror) { fetch_mirror(repository) }
   end