Merge branch 'measure-proxy-timing' into 'master'

Measure proxy flight time

See merge request !4278

1 files changed, 24 insertions, 0 deletions

diff --git a/lib/gitlab/middleware/rails_queue_duration.rb b/lib/gitlab/middleware/rails_queue_duration.rb
new file mode 100644
index 00000000000..56608b1b276
--- /dev/null
+++ b/lib/gitlab/middleware/rails_queue_duration.rb
@@ -0,0 +1,24 @@
+# This Rack middleware is intended to measure the latency between
+# gitlab-workhorse forwarding a request to the Rails application and the
+# time this middleware is reached.
+
+module Gitlab
+  module Middleware
+    class RailsQueueDuration
+      def initialize(app)
+        @app = app
+      end
+      
+      def call(env)
+        trans = Gitlab::Metrics.current_transaction
+        proxy_start = env['HTTP_GITLAB_WORHORSE_PROXY_START'].presence
+        if trans && proxy_start
+          # Time in milliseconds since gitlab-workhorse started the request
+          trans.set(:rails_queue_duration, Time.now.to_f * 1_000 - proxy_start.to_f / 1_000_000)
+        end
+
+        @app.call(env)
+      end
+    end
+  end
+end