upstream timed out (110: Connection timed out) while reading response header from upstr

[rhand]

See Matt.ias.be's blog post
https://ma.ttias.be/nginx-and-php-fpm-upstream-timed-out-failed-110-connection-timed-out-or-reset-by-peer-while-reading/
for some tips on debugging. Can be tough sometimes though.  In my Kubernetes
/ Docker case it was the wrong fastcig_pass in nginx config and the wrong
container port. See https://imwz.io/docker-nginx-502-bad-gateway/

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,30793,290430#msg-290430