Add Default Initial Branch Name for Repositories Group Setting

app/controllers/groups_controller.rb

@@ -132,13 +132,23 @@ class GroupsController < Groups::ApplicationController
 
   def update
     if Groups::UpdateService.new(@group, current_user, group_params).execute
-      redirect_to edit_group_path(@group, anchor: params[:update_section]), notice: "Group '#{@group.name}' was successfully updated."
+      notice = "Group '#{@group.name}' was successfully updated."
+
+      redirect_to edit_group_origin_location, notice: notice
     else
       @group.reset
       render action: "edit"
     end
   end
 
+  def edit_group_origin_location
+    if params.dig(:group, :redirect_target) == 'repository_settings'
+      group_settings_repository_path(@group, anchor: 'js-default-branch-name')
+    else
+      edit_group_path(@group, anchor: params[:update_section])
+    end
+  end
+
   def destroy
     Groups::DestroyService.new(@group, current_user).async_execute
 

app/models/group.rb

@@ -109,6 +109,8 @@ class Group < Namespace
       .where("project_authorizations.user_id IN (?)", user_ids)
   end
 
+  delegate :default_branch_name, to: :namespace_settings
+
   class << self
     def sort_by_attribute(method)
       if method == 'storage_size_desc'

app/models/namespace_setting.rb

@@ -6,10 +6,18 @@ class NamespaceSetting < ApplicationRecord
   validate :default_branch_name_content
   validate :allow_mfa_for_group
 
+  before_validation :normalize_default_branch_name
+
   NAMESPACE_SETTINGS_PARAMS = [:default_branch_name].freeze
 
   self.primary_key = :namespace_id
 
+  private
+
+  def normalize_default_branch_name
+    self.default_branch_name = nil if default_branch_name.blank?
+  end
+
   def default_branch_name_content
     return if default_branch_name.nil?
 

app/views/groups/settings/repository/_initial_branch_name.html.haml

+%section.settings.as-default-branch-name.no-animate#js-default-branch-name{ class: ('expanded' if expanded_by_default?) }
+  .settings-header
+    %h4
+      = _('Default initial branch name')
+    %button.gl-button.js-settings-toggle{ type: 'button' }
+      = expanded_by_default? ? _('Collapse') : _('Expand')
+    %p
+      = _('Set the default name of the initial branch when creating new repositories through the user interface.')
+  .settings-content
+    = form_for @group, url: group_path(@group, anchor: 'js-default-branch-name'), html: { class: 'fieldset-form' } do |f|
+      = form_errors(@group)
+      - fallback_branch_name = '<code>master</code>'
+
+      %fieldset
+        .form-group
+          = f.label :default_branch_name, _('Default initial branch name'), class: 'label-light'
+          = f.text_field :default_branch_name, value: group.namespace_settings&.default_branch_name, placeholder: 'master', class: 'form-control'
+          %span.form-text.text-muted
+            = (_("Changes affect new repositories only. If not specified, either the configured application-wide default or Git's default name %{branch_name_default} will be used.") % { branch_name_default: fallback_branch_name }).html_safe
+
+      = f.hidden_field :redirect_target, value: "repository_settings"
+      = f.submit _('Save changes'), class: 'gl-button btn-success'

app/views/groups/settings/repository/show.html.haml

@@ -4,3 +4,4 @@
 - deploy_token_description = s_('DeployTokens|Group deploy tokens allow access to the packages, repositories, and registry images within the group.')
 
 = render "shared/deploy_tokens/index", group_or_project: @group, description: deploy_token_description
+= render "initial_branch_name", group: @group

changelogs/unreleased/feature-group-default-initial-branch-name.yml

+---
+title: Add Default Initial Branch Name for Repositories Group Setting
+merge_request: 43290
+author:
+type: added

doc/user/group/index.md

@@ -518,6 +518,23 @@ If you want to retain ownership over the original namespace and
 protect the URL redirects, then instead of changing a group's path or renaming a
 username, you can create a new group and transfer projects to it.
 
+### Group repository settings
+
+You can change settings that are specific to repositories in your group.
+
+#### Custom initial branch name **(CORE ONLY)**
+
+> - [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/43290) in GitLab 13.6.
+
+By default, when you create a new project in GitLab, the initial branch is called `master`.
+For groups, a group administrator can customize the initial branch name to something
+else. This way, every new project created under that group from then on will start from the custom branch name rather than `master`. To do so:
+
+1. Go to the **Group page > Settings > Repository** and expand **Default initial
+   branch name**.
+1. Change the default initial branch to a custom name of your choice.
+1. **Save Changes**.
+
 ### Remove a group
 
 To remove a group and its contents:

locale/gitlab.pot

@@ -4929,6 +4929,9 @@ msgstr ""
 msgid "Changes affect new repositories only. If not specified, Git's default name %{branch_name_default} will be used."
 msgstr ""
 
+msgid "Changes affect new repositories only. If not specified, either the configured application-wide default or Git's default name %{branch_name_default} will be used."
+msgstr ""
+
 msgid "Changes are shown as if the %{b_open}source%{b_close} revision was being merged into the %{b_open}target%{b_close} revision."
 msgstr ""
 

spec/features/groups/settings/repository_spec.rb

@@ -25,4 +25,21 @@ RSpec.describe 'Group Repository settings' do
       let(:entity_type) { 'group' }
     end
   end
+
+  context 'Default initial branch name' do
+    before do
+      visit group_settings_repository_path(group)
+    end
+
+    it 'has the setting section' do
+      expect(page).to have_css("#js-default-branch-name")
+    end
+
+    it 'renders the correct setting section content' do
+      within("#js-default-branch-name") do
+        expect(page).to have_content("Default initial branch name")
+        expect(page).to have_content("Set the default name of the initial branch when creating new repositories through the user interface.")
+      end
+    end
+  end
 end

spec/models/namespace_setting_spec.rb

@@ -36,13 +36,10 @@ RSpec.describe NamespaceSetting, type: :model do
 
       context "when an empty string" do
         before do
-          namespace_settings.default_branch_name = ''
+          namespace_settings.default_branch_name = ""
         end
 
-        it "returns an error" do
-          expect(namespace_settings.valid?).to be_falsey
-          expect(namespace_settings.errors.full_messages).not_to be_empty
-        end
+        it_behaves_like "doesn't return an error"
       end
     end