Add `feature_category`-label to grape metrics

This adds the `feature_category` label to the metrics for grape
endpoints. This is needed so the metrics have the same labels as the
ones for controllers.

This also adds a spec so we don't forget about it in the future.

lib/gitlab/metrics/web_transaction.rb

@@ -65,7 +65,10 @@ module Gitlab
 
         if route
           path = endpoint_paths_cache[route.request_method][route.path]
-          { controller: 'Grape', action: "#{route.request_method} #{path}" }
+
+          # Feature categories will be added for grape endpoints in
+          # https://gitlab.com/gitlab-com/gl-infra/scalability/-/issues/462
+          { controller: 'Grape', action: "#{route.request_method} #{path}", feature_category: "" }
         end
       end
 

spec/lib/gitlab/metrics/web_transaction_spec.rb

@@ -70,6 +70,9 @@ RSpec.describe Gitlab::Metrics::WebTransaction do
   end
 
   describe '#labels' do
+    let(:request) { double(:request, format: double(:format, ref: :html)) }
+    let(:controller_class) { double(:controller_class, name: 'TestController') }
+
     context 'when request goes to Grape endpoint' do
       before do
         route = double(:route, request_method: 'GET', path: '/:version/projects/:id/archive(.:format)')
@@ -77,8 +80,9 @@ RSpec.describe Gitlab::Metrics::WebTransaction do
 
         env['api.endpoint'] = endpoint
       end
+
       it 'provides labels with the method and path of the route in the grape endpoint' do
-        expect(transaction.labels).to eq({ controller: 'Grape', action: 'GET /projects/:id/archive' })
+        expect(transaction.labels).to eq({ controller: 'Grape', action: 'GET /projects/:id/archive', feature_category: '' })
       end
 
       it 'does not provide labels if route infos are missing' do
@@ -92,9 +96,6 @@ RSpec.describe Gitlab::Metrics::WebTransaction do
     end
 
     context 'when request goes to ActionController' do
-      let(:request) { double(:request, format: double(:format, ref: :html)) }
-      let(:controller_class) { double(:controller_class, name: 'TestController') }
-
       before do
         controller = double(:controller, class: controller_class, action_name: 'show', request: request)
 
@@ -129,6 +130,19 @@ RSpec.describe Gitlab::Metrics::WebTransaction do
       end
     end
 
+    it 'returns the same labels for API and controller requests' do
+      route = double(:route, request_method: 'GET', path: '/:version/projects/:id/archive(.:format)')
+      endpoint = double(:endpoint, route: route)
+      api_env = { 'api.endpoint' => endpoint }
+      api_labels = described_class.new(api_env).labels
+
+      controller = double(:controller, class: controller_class, action_name: 'show', request: request)
+      controller_env = { 'action_controller.instance' => controller }
+      controller_labels = described_class.new(controller_env).labels
+
+      expect(api_labels.keys).to contain_exactly(*controller_labels.keys)
+    end
+
     it 'returns no labels when no route information is present in env' do
       expect(transaction.labels).to eq({})
     end