Add read-only banner to all pages

When the database is in a read-only state, display a banner on each
page informing the user they cannot write to that GitLab instance.

EE counterpart of gitlab-org/gitlab-ce!17798.

app/helpers/application_helper.rb

@@ -2,6 +2,8 @@ require 'digest/md5'
 require 'uri'
 
 module ApplicationHelper
+  prepend EE::ApplicationHelper
+
   # Check if a particular controller is the current one
   #
   # args - One or more controller names to check
@@ -327,4 +329,11 @@ module ApplicationHelper
   def locale_path
     asset_path("locale/#{Gitlab::I18n.locale}/app.js")
   end
+
+  # Overridden in EE
+  def read_only_message
+    return unless Gitlab::Database.read_only?
+
+    _('You are on a read-only GitLab instance.')
+  end
 end

app/views/layouts/_page.html.haml

@@ -7,7 +7,7 @@
     .alert-wrapper
       = render "layouts/header/ee_license_banner"
       = render "layouts/broadcast"
-      = render 'layouts/header/ee/geo_secondary_banner'
+      = render 'layouts/header/read_only_banner'
       = render "layouts/nav/ee/classification_level_banner"
       = yield :flash_message
       - unless @hide_breadcrumbs

app/views/layouts/header/_read_only_banner.html.haml

+- message = read_only_message
+- if message
+  .flash-container.flash-container-page
+    .flash-notice
+      %div{ class: (container_class) }
+        %span
+          = message

changelogs/unreleased/tc-re-add-read-only-banner.yml

+---
+title: Add read-only banner to all pages
+merge_request: 17798
+author:
+type: fixed

ee/app/helpers/ee/application_helper.rb

+module EE
+  module ApplicationHelper
+    extend ::Gitlab::Utils::Override
+
+    override :read_only_message
+    def read_only_message
+      return super unless ::Gitlab::Geo.secondary_with_primary?
+
+      (_('You are on a secondary (read-only) Geo node. If you want to make any changes, you must visit the %{primary_node}.') %
+        { primary_node: link_to('primary node', ::Gitlab::Geo.primary_node.url) }).html_safe
+    end
+  end
+end

ee/app/views/layouts/header/ee/_geo_secondary_banner.html.haml

-- if ::Gitlab::Geo.secondary? && ::Gitlab::Geo.primary_node
-  - primary_node = link_to('primary node', ::Gitlab::Geo.primary_node.url)
-  .flash-container.flash-container-page
-    .flash-notice
-      %div{ class: (container_class) }
-        %span You are on a secondary (read-only) Geo node. If you want to make any changes, you must visit the #{primary_node}.

ee/spec/features/read_only_spec.rb

+require 'rails_helper'
+
+describe 'Geo read-only message' do
+  include ::EE::GeoHelpers
+
+  set(:user) { create(:user) }
+  set(:primary) { create(:geo_node, :primary) }
+  set(:secondary) { create(:geo_node) }
+
+  before do
+    sign_in(user)
+  end
+
+  it 'shows read-only banner when on a Geo secondary' do
+    stub_current_geo_node(secondary)
+
+    visit root_dashboard_path
+
+    expect(page).to have_content('You are on a secondary (read-only) Geo node')
+  end
+end

spec/features/read_only_spec.rb

+require 'rails_helper'
+
+describe 'read-only message' do
+  set(:user) { create(:user) }
+
+  before do
+    sign_in(user)
+  end
+
+  it 'shows read-only banner when database is read-only' do
+    allow(Gitlab::Database).to receive(:read_only?).and_return(true)
+
+    visit root_dashboard_path
+
+    expect(page).to have_content('You are on a read-only GitLab instance.')
+  end
+
+  it 'does not show read-only banner when database is able to read-write' do
+    allow(Gitlab::Database).to receive(:read_only?).and_return(false)
+
+    visit root_dashboard_path
+
+    expect(page).not_to have_content('You are on a read-only GitLab instance.')
+  end
+end