Fairly abstract - Facebook Engineering - https://m.facebook.com/nt/screen/?params=%7B%22note_id%22%3A10158791436142200%7D&path=%2Fnotes%2Fnote%2F&_rdr

Also, Cloudflare’s take on the outage - https://blog.cloudflare.com/october-2021-facebook-outage/

They have a monkey patch subsystem. Lol.

Mike