Hide generic alert endpoint behind a feature flag

ee/app/controllers/projects/alert_notifications_controller.rb

@@ -7,6 +7,7 @@ module Projects
     skip_before_action :project
 
     prepend_before_action :repository, :project_without_auth
+    before_action :check_generic_alert_endpoint_feature_flag!
 
     def create
       head :ok
@@ -22,5 +23,9 @@ module Projects
 
       @project = Project.find_by_full_path("#{namespace}/#{id}")
     end
+
+    def check_generic_alert_endpoint_feature_flag!
+      render_404 unless Feature.enabled?(:generic_alert_endpoint, @project)
+    end
   end
 end

ee/spec/controllers/projects/alert_notifications_controller_spec.rb

@@ -7,10 +7,32 @@ describe Projects::AlertNotificationsController do
   set(:environment) { create(:environment, project: project) }
 
   describe 'POST #create' do
-    it 'returns ok' do
+    def make_request(opts = {})
       post :create, params: project_params, session: { as: :json }
+    end
+
+    context 'when feature flag is on' do
+      before do
+        stub_feature_flags(generic_alert_endpoint: true)
+      end
+
+      it 'responds with ok' do
+        make_request
+
+        expect(response).to have_gitlab_http_status(:ok)
+      end
+    end
+
+    context 'when feature flag is off' do
+      before do
+        stub_feature_flags(generic_alert_endpoint: false)
+      end
+
+      it 'responds with not_found' do
+        make_request
 
-      expect(response).to have_gitlab_http_status(:ok)
+        expect(response).to have_gitlab_http_status(:not_found)
+      end
     end
   end