Synchronize the default branch in secondary nodes

ee/app/models/ee/repository.rb

@@ -10,7 +10,7 @@ module EE
     MIRROR_REMOTE = "upstream".freeze
 
     included do
-      delegate :checksum, to: :raw_repository
+      delegate :checksum, :find_remote_root_ref, to: :raw_repository
     end
 
     # Transiently sets a configuration variable

ee/app/services/geo/repository_sync_service.rb

@@ -6,9 +6,7 @@ module Geo
 
     def sync_repository
       fetch_repository
-
-      update_gitattributes
-
+      update_default_branch
       mark_sync_as_successful
     rescue Gitlab::Shell::Error => e
       # In some cases repository does not exist, the only way to know about this is to parse the error text.
@@ -47,11 +45,10 @@ module Geo
       project.ensure_repository
     end
 
-    # Update info/attributes file using the contents of .gitattributes file from the default branch
-    def update_gitattributes
-      return if project.default_branch.nil?
-
-      repository.copy_gitattributes(project.default_branch)
+    # Update the default branch querying the remote to determine its HEAD
+    def update_default_branch
+      root_ref = repository.find_remote_root_ref(GEO_REMOTE_NAME)
+      project.change_head(root_ref) if root_ref.present?
     end
 
     def schedule_repack

ee/spec/services/geo/repository_sync_service_spec.rb

@@ -31,6 +31,11 @@ describe Geo::RepositorySyncService do
 
       allow_any_instance_of(Repository).to receive(:fetch_as_mirror)
         .and_return(true)
+
+      allow_any_instance_of(Repository)
+        .to receive(:find_remote_root_ref)
+        .with('geo')
+        .and_return('master')
     end
 
     it 'fetches project repository with JWT credentials' do
@@ -215,6 +220,17 @@ describe Geo::RepositorySyncService do
 
             subject.execute
           end
+
+          it 'updates the default branch' do
+            allow(project.repository)
+              .to receive(:find_remote_root_ref)
+              .with('geo')
+              .and_return('development')
+
+            expect(project).to receive(:change_head).with('development').once
+
+            subject.execute
+          end
         end
       end