Nginx - Rate limit when origin server response code is 401

[viet]

Hello Krishna,

I have a similar question asking here
https://serverfault.com/questions/907860/nginx-limit-request-based-on-response-status-code
(no reply yet).

I've tried several combinations, but haven't found any working solution yet.
It seems that limit was done in "receiving" state of requests only, which
mean $status is always null.

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,279547,279582#msg-279582