Move alert management behind a feature flag

app/controllers/projects/alert_management_controller.rb

 # frozen_string_literal: true
 
 class Projects::AlertManagementController < Projects::ApplicationController
+  before_action :ensure_feature_enabled
+
   def index
-    respond_to do |format|
-      format.html
   end
+
+  private
+
+  def ensure_feature_enabled
+    render_404 unless Feature.enabled?(:alert_management_minimal, project)
   end
 end

app/views/layouts/nav/sidebar/_project.html.haml

@@ -222,12 +222,14 @@
                   %span
                     = _('Metrics')
 
+            - if Feature.enabled?(:alert_management_minimal, @project)
               - if project_nav_tab?(:alert_management)
                 = nav_link(controller: :alert_management) do
                   = link_to project_alert_management_index_path(@project), title: _('Alerts'), class: 'shortcuts-tracking qa-operations-tracking-link' do
                     %span
                       = _('Alerts')
 
+            - if project_nav_tab? :environments
               = render_if_exists "layouts/nav/sidebar/tracing_link"
 
               = nav_link(controller: :environments, action: [:index, :folder, :show, :new, :edit, :create, :update, :stop, :terminal]) do

changelogs/unreleased/tr-alert-management-feature-flag.yml

+---
+title: Move alert management behind a feature flag
+merge_request: 30133
+author:
+type: fixed

spec/controllers/projects/alert_management_controller_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Projects::AlertManagementController do
+  let_it_be(:project) { create(:project) }
+  let_it_be(:role) { :reporter }
+  let_it_be(:user) { create(:user) }
+
+  before do
+    project.add_role(user, role)
+    sign_in(user)
+  end
+
+  describe 'GET #index' do
+    context 'when alert_management_minimal is enabled' do
+      before do
+        stub_feature_flags(alert_management_minimal: true)
+      end
+
+      it 'shows the page' do
+        get :index, params: { namespace_id: project.namespace, project_id: project }
+
+        expect(response).to have_gitlab_http_status(:ok)
+      end
+    end
+
+    context 'when alert_management_minimal is disabled' do
+      before do
+        stub_feature_flags(alert_management_minimal: false)
+      end
+
+      it 'shows 404' do
+        get :index, params: { namespace_id: project.namespace, project_id: project }
+
+        expect(response).to have_gitlab_http_status(:not_found)
+      end
+    end
+  end
+end

spec/views/layouts/nav/sidebar/_project.html.haml_spec.rb

@@ -136,6 +136,7 @@ describe 'layouts/nav/sidebar/_project' do
   end
 
   describe 'operations settings tab' do
+    describe 'archive projects' do
       before do
         project.update!(archived: project_archived)
       end
@@ -161,6 +162,33 @@ describe 'layouts/nav/sidebar/_project' do
       end
     end
 
+    describe 'Alert Management' do
+      context 'when alert_management_minimal is enabled' do
+        before do
+          stub_feature_flags(alert_management_minimal: true)
+        end
+
+        it 'shows the Alerts sidebar entry' do
+          render
+
+          expect(rendered).to have_css('a[title="Alerts"]')
+        end
+      end
+
+      context 'when alert_management_minimal is disabled' do
+        before do
+          stub_feature_flags(alert_management_minimal: false)
+        end
+
+        it 'does not show the Alerts sidebar entry' do
+          render
+
+          expect(rendered).to have_no_css('a[title="Alerts"]')
+        end
+      end
+    end
+  end
+
   describe 'value stream analytics entry' do
     let(:read_cycle_analytics) { true }