handling x_forwarded_proto with Nginx as backend to HAproxy

[jaychris]

Running Nginx 1.2.7 behind HAproxy, with SSL being terminated on on HAproxy.
 I was using the X_FORWARDED_PROTO header to make some decisions on the
backend when I was using Apache, but it doesn't look like Nginx is handling
the header currently:

client sent invalid header line: "X_FORWARDED_PROTO: http" while reading
client request headers,

I found an old thread that seemed to address this, with Igor suggesting to
use:

http {
   map $http_x_forwarded_proto $my_https {
  default off;
  https on;
}

server {
  ...
  location {
    ...;
    fastcgi_param HTTPS $my_https;
  }
}

but this doesn't seem to be carrying the header forward.  Maybe it's a lack
of understanding on my part or maybe the way the issue is handled has
changed in the years since that post (HERE:
http://osdir.com/ml/nginx/2010-05/msg00101.html), but if anyone has a
suggestion I would appreciate it.

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,238384,238384#msg-238384