Return Specific Error Page in NGinX when all the upstream servers are marked down

[shivramg94]

I have an upstream block as follows

upstream sample{
    server abc1.example.com down;
    server abd2.example.com down;
}

Currently I get a 502 error. In this special case where I receive a 502 and
all upstream servers are down I would like a receive a specific error page
as temporarily unavailable.

How can i achieve that?

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,274075,274075#msg-274075