Expose API feature categories in logs and metrics

lib/api/api.rb

@@ -48,11 +48,17 @@ module API
     before do
       coerce_nil_params_to_array!
 
+      api_endpoint = env['api.endpoint']
+      feature_category = api_endpoint.options[:for].try(:feature_category_for_app, api_endpoint).to_s
+
+      header[Gitlab::Metrics::RequestsRackMiddleware::FEATURE_CATEGORY_HEADER] = feature_category
+
       Gitlab::ApplicationContext.push(
         user: -> { @current_user },
         project: -> { @project },
         namespace: -> { @group },
-        caller_id: route.origin
+        caller_id: route.origin,
+        feature_category: feature_category
       )
     end
 

lib/api/internal/base.rb

@@ -7,14 +7,16 @@ module API
       before { authenticate_by_gitlab_shell_token! }
 
       before do
-        route_path = route.origin
-        route_class = route.app.options[:for]
+        api_endpoint = env['api.endpoint']
+        feature_category = api_endpoint.options[:for].try(:feature_category_for_app, api_endpoint).to_s
+
+        header[Gitlab::Metrics::RequestsRackMiddleware::FEATURE_CATEGORY_HEADER] = feature_category
 
         Gitlab::ApplicationContext.push(
           user: -> { actor&.user },
           project: -> { project },
-          caller_id: route_path,
-          feature_category: route_class.try(:feature_category_for_action, route_path).to_s
+          caller_id: route.origin,
+          feature_category: feature_category
         )
       end
 

spec/requests/api/api_spec.rb

@@ -92,4 +92,36 @@ RSpec.describe API::API do
       end
     end
   end
+
+  context 'application context' do
+    let_it_be(:project) { create(:project) }
+    let_it_be(:user) { project.owner }
+
+    it 'logs all application context fields' do
+      allow_any_instance_of(Gitlab::GrapeLogging::Loggers::ContextLogger).to receive(:parameters) do
+        Labkit::Context.current.to_h.tap do |log_context|
+          expect(log_context).to match('correlation_id' => an_instance_of(String),
+                                       'meta.caller_id' => '/api/:version/projects/:id/issues',
+                                       'meta.project' => project.full_path,
+                                       'meta.root_namespace' => project.namespace.full_path,
+                                       'meta.user' => user.username,
+                                       'meta.feature_category' => 'issue_tracking')
+        end
+      end
+
+      get(api("/projects/#{project.id}/issues", user))
+    end
+
+    it 'skips fields that do not apply' do
+      allow_any_instance_of(Gitlab::GrapeLogging::Loggers::ContextLogger).to receive(:parameters) do
+        Labkit::Context.current.to_h.tap do |log_context|
+          expect(log_context).to match('correlation_id' => an_instance_of(String),
+                                       'meta.caller_id' => '/api/:version/users',
+                                       'meta.feature_category' => 'users')
+        end
+      end
+
+      get(api('/users'))
+    end
+  end
 end