Log queue duration in production_json.log

`queue_duration` is a useful metric that is currently in api_json.log
but not in production_json.log. We should add it because it tells us how
long the request sat in Workhorse before Unicorn processed it. Having
this field enables the support team to better troubleshoot when delays
began to happen.

1 files changed, 3 insertions, 0 deletions

diff --git a/lib/gitlab/middleware/rails_queue_duration.rb b/lib/gitlab/middleware/rails_queue_duration.rb
index 96c6a0a7d28..a147e165262 100644
--- a/lib/gitlab/middleware/rails_queue_duration.rb
+++ b/lib/gitlab/middleware/rails_queue_duration.rb
@@ -7,6 +7,8 @@
 module Gitlab
   module Middleware
     class RailsQueueDuration
+      GITLAB_RAILS_QUEUE_DURATION_KEY = 'GITLAB_RAILS_QUEUE_DURATION'
+
       def initialize(app)
         @app = app
       end
@@ -19,6 +21,7 @@ module Gitlab
           duration = Time.now.to_f * 1_000 - proxy_start.to_f / 1_000_000
           trans.set(:rails_queue_duration, duration)
           metric_rails_queue_duration_seconds.observe(trans.labels, duration / 1_000)
+          env[GITLAB_RAILS_QUEUE_DURATION_KEY] = duration.round(2)
         end
 
         @app.call(env)