It's an internal system, but it was discussed at F8 last year. Here's the video (https://www.youtube.com/watch?v=X0VH78ye4yY#t=31m30s https://www.youtube.com/wa

It's an internal system, but it was discussed at F8 last year. Here's the video (https://www.youtube.com/watch?v=X0VH78ye4yY#t=31m30s https://www.youtube.com/watch?v=X0VH78ye4yY#t=31m30s) and someone's notes on it (http://gregoryszorc.com/blog/2015/03/28/notes-from-facebook's-developer-infrastructure-at-scale-f8-talk/ http://gregoryszorc.com/blog/2015/03/28/notes-from-facebook'...).