Add pull mirror branch prefix

With this setting we can set a prefix to branches during pull mirroring

changelogs/unreleased/ac-pull-mirror-branch-prefix.yml

+---
+title: Add pull_mirror_branch_prefix column on projects table
+merge_request: 17368
+author:
+type: added

db/migrate/20190924124627_add_pull_mirror_branch_prefix_to_projects.rb

+# frozen_string_literal: true
+
+class AddPullMirrorBranchPrefixToProjects < ActiveRecord::Migration[5.2]
+  DOWNTIME = false
+
+  def change
+    add_column :projects, :pull_mirror_branch_prefix, :string, limit: 50
+  end
+end

db/schema.rb

@@ -2922,6 +2922,7 @@ ActiveRecord::Schema.define(version: 2019_09_27_074328) do
     t.boolean "emails_disabled"
     t.integer "max_pages_size"
     t.integer "max_artifacts_size"
+    t.string "pull_mirror_branch_prefix", limit: 50
     t.index "lower((name)::text)", name: "index_projects_on_lower_name"
     t.index ["archived", "pending_delete", "merge_requests_require_code_owner_approval"], name: "projects_requiring_code_owner_approval", where: "((pending_delete = false) AND (archived = false) AND (merge_requests_require_code_owner_approval = true))"
     t.index ["created_at"], name: "index_projects_on_created_at"

ee/app/controllers/ee/projects/mirrors_controller.rb

@@ -67,6 +67,7 @@ module EE
           :mirror_trigger_builds,
           :only_mirror_protected_branches,
           :mirror_overwrites_diverged_branches,
+          :pull_mirror_branch_prefix,
 
           import_data_attributes: %i[
             id

ee/app/models/ee/project.rb

@@ -140,6 +140,9 @@ module EE
 
       validates :approvals_before_merge, numericality: true, allow_blank: true
 
+      validates :pull_mirror_branch_prefix, length: { maximum: 50 }
+      validate :check_pull_mirror_branch_prefix
+
       with_options if: :mirror? do
         validates :import_url, presence: true
         validates :mirror_user, presence: true
@@ -671,5 +674,14 @@ module EE
     def validate_board_limit(board)
       # Board limits are disabled in EE, so this method is just a no-op.
     end
+
+    def check_pull_mirror_branch_prefix
+      return if pull_mirror_branch_prefix.blank?
+      return unless pull_mirror_branch_prefix_changed?
+
+      unless ::Gitlab::GitRefValidator.validate("#{pull_mirror_branch_prefix}master")
+        errors.add(:pull_mirror_branch_prefix, _('Invalid Git ref'))
+      end
+    end
   end
 end

ee/app/services/projects/update_mirror_service.rb

@@ -34,7 +34,7 @@ module Projects
       errors = []
 
       repository.upstream_branches.each do |upstream_branch|
-        name = upstream_branch.name
+        name = target_branch_name(upstream_branch.name)
 
         next if skip_branch?(name)
 
@@ -147,5 +147,11 @@ module Projects
     def log_error(error_message)
       service_logger.error(base_payload.merge(error_message: error_message))
     end
+
+    def target_branch_name(upstream_branch_name)
+      return upstream_branch_name unless Feature.enabled?(:pull_mirror_branch_prefix, project)
+
+      "#{project.pull_mirror_branch_prefix}#{upstream_branch_name}"
+    end
   end
 end

ee/app/views/projects/mirrors/_mirror_repos_form.html.haml

@@ -37,6 +37,13 @@
     .help-block
       = _('This user will be the author of all events in the activity feed that are the result of an update, like new branches being created or new commits being pushed to existing branches. Upon creation or when reassigning you can only assign yourself to be the mirror user.')
 
+  - if Feature.enabled?(:pull_mirror_branch_prefix, @project)
+    .form-group
+      = f.label :pull_mirror_branch_prefix, _('Branch prefix'), class: 'label-light'
+      = f.text_field :pull_mirror_branch_prefix, class: 'form-control', placeholder: 'Example: upstream/'
+      .help-block
+        = _("Mirrored branches will have this prefix. If you enabled 'Only mirror protected branches' you need to include this prefix on protected branches in this project or nothing will be mirrored.")
+
   .form-check.append-bottom-10
     = f.check_box :mirror_overwrites_diverged_branches, class: 'form-check-input', checked: false
     = f.label :mirror_overwrites_diverged_branches, _('Overwrite diverged branches'), class: 'form-check-label'

ee/spec/features/projects/settings/ee/repository_mirrors_settings_spec.rb

@@ -26,6 +26,7 @@ describe 'Project settings > [EE] repository' do
         expect(page).to have_no_selector('#project_mirror_user_id', visible: false)
         expect(page).to have_no_selector('#project_mirror_overwrites_diverged_branches')
         expect(page).to have_no_selector('#project_mirror_trigger_builds')
+        expect(page).to have_no_selector('#project_pull_mirror_branch_prefix')
       end
     end
   end
@@ -45,6 +46,21 @@ describe 'Project settings > [EE] repository' do
         expect(page).to have_selector('#project_mirror_user_id', visible: false)
         expect(page).to have_selector('#project_mirror_overwrites_diverged_branches')
         expect(page).to have_selector('#project_mirror_trigger_builds')
+        expect(page).to have_selector('#project_pull_mirror_branch_prefix')
+      end
+    end
+
+    context 'pull_mirror_branch_prefix feature flag disabled' do
+      before do
+        stub_feature_flags(pull_mirror_branch_prefix: false)
+      end
+
+      it 'shows pull mirror settings', :js do
+        visit project_settings_repository_path(project)
+
+        page.within('.project-mirror-settings') do
+          expect(page).to have_no_selector('#project_pull_mirror_branch_prefix')
+        end
       end
     end
 

ee/spec/models/project_spec.rb

@@ -193,6 +193,16 @@ describe Project do
         project2.update(mirror: true, import_url: generate(:url), mirror_user: project.creator)
       end.to change { ProjectImportState.where(project: project2).count }.from(0).to(1)
     end
+
+    describe 'pull_mirror_branch_prefix' do
+      it { is_expected.to validate_length_of(:pull_mirror_branch_prefix).is_at_most(50) }
+
+      it 'rejects invalid git refs' do
+        project = build(:project, pull_mirror_branch_prefix: 'an invalid prefix..')
+
+        expect(project).not_to be_valid
+      end
+    end
   end
 
   describe 'setting up a mirror' do

ee/spec/services/projects/update_mirror_service_spec.rb

@@ -140,6 +140,38 @@ describe Projects::UpdateMirrorService do
     end
 
     context "updating branches" do
+      context 'when pull_mirror_branch_prefix is set' do
+        let(:pull_mirror_branch_prefix) { 'upstream/' }
+
+        before do
+          project.update(pull_mirror_branch_prefix: pull_mirror_branch_prefix)
+        end
+
+        it "creates new branches" do
+          stub_fetch_mirror(project)
+
+          service.execute
+
+          expect(project.repository.branch_names).to include("#{pull_mirror_branch_prefix}new-branch")
+          expect(project.repository.branch_names).not_to include('new-branch')
+        end
+
+        context 'when pull_mirror_branch_prefix feature flag is disabled' do
+          before do
+            stub_feature_flags(pull_mirror_branch_prefix: false)
+          end
+
+          it "creates new branches" do
+            stub_fetch_mirror(project)
+
+            service.execute
+
+            expect(project.repository.branch_names).not_to include("#{pull_mirror_branch_prefix}new-branch")
+            expect(project.repository.branch_names).to include('new-branch')
+          end
+        end
+      end
+
       context 'when mirror only protected branches option is set' do
         let(:new_protected_branch_name) { 'new-branch' }
         let(:protected_branch_name) { 'existing-branch' }

lib/gitlab/import_export/import_export.yml

@@ -139,6 +139,7 @@ excluded_attributes:
     - :mirror_trigger_builds
     - :only_mirror_protected_branches
     - :pull_mirror_available_overridden
+    - :pull_mirror_branch_prefix
     - :mirror_overwrites_diverged_branches
     - :packages_enabled
     - :mirror_last_update_at

locale/gitlab.pot

@@ -2421,6 +2421,9 @@ msgstr ""
 msgid "Branch not loaded - %{branchId}"
 msgstr ""
 
+msgid "Branch prefix"
+msgstr ""
+
 msgid "BranchSwitcherPlaceholder|Search branches"
 msgstr ""
 
@@ -8688,6 +8691,9 @@ msgstr ""
 msgid "Introducing Your Conversational Development Index"
 msgstr ""
 
+msgid "Invalid Git ref"
+msgstr ""
+
 msgid "Invalid Insights config file detected"
 msgstr ""
 
@@ -10168,6 +10174,9 @@ msgstr ""
 msgid "Mirror user"
 msgstr ""
 
+msgid "Mirrored branches will have this prefix. If you enabled 'Only mirror protected branches' you need to include this prefix on protected branches in this project or nothing will be mirrored."
+msgstr ""
+
 msgid "Mirrored repositories"
 msgstr ""