1 files changed, 46 insertions, 0 deletions
diff --git a/lib/gitlab/rack_timeout_observer.rb b/lib/gitlab/rack_timeout_observer.rb
new file mode 100644
index 00000000000..80d3f7dea60
--- /dev/null
+++ b/lib/gitlab/rack_timeout_observer.rb
@@ -0,0 +1,46 @@
+# frozen_string_literal: true
+
+module Gitlab
+  class RackTimeoutObserver
+    def initialize
+      @counter = Gitlab::Metrics.counter(:rack_state_total, 'Number of requests in a given rack state')
+    end
+
+    # returns the Proc to be used as the observer callback block
+    def callback
+      method(:log_timeout_exception)
+    end
+
+    private
+
+    def log_timeout_exception(env)
+      info = env[::Rack::Timeout::ENV_INFO_KEY]
+      return unless info
+
+      @counter.increment(labels(info, env))
+    end
+
+    def labels(info, env)
+      params = controller_params(env) || grape_params(env) || {}
+
+      {
+        controller: params['controller'],
+        action: params['action'],
+        route: params['route'],
+        state: info.state
+      }
+    end
+
+    def controller_params(env)
+      env['action_dispatch.request.parameters']
+    end
+
+    def grape_params(env)
+      endpoint = env[Grape::Env::API_ENDPOINT]
+      route = endpoint&.route&.pattern&.origin
+      return unless route
+
+      { 'route' => route }
+    end
+  end
+end