Set FastCGI param if exists header

[Tio Oscar]

Hi guys.

I have a one frontend server with nginx, and 5 backends with PHP-FPM, I do
a FastCGI pass and all works.

Now, I need add other fronted, balanced by hardware base balancer.

My problem is, i need track the remote IP address, is very very important,
in the fastcgi_params file, actualu REMOTE_ADDR param is set as
$remote_addr.

The balancer sendme a header called x_cluster_client_ip (yes, is ungly), i
recive this in nginx as $http_x_cluster_client_ip, but if I replace this
param and reload/restart nginx, before DNS change at the new balancer, i
don't get the x_cluster_client_ip value and i don't can't know the ip.

there is some form of define REMOTE_ADDR as $http_x_cluster_client_ip if
exists and $remote_addr else?

-- 
El Tio ~ Programador, hacker y filósofo
web: http://blog.exodica.com.ar
Linked'in: http://www.linkedin.com/in/ogentilezza
Twitter: @exos, Indeti.ca: @exos
Tels: [+54 11] 638-LINUX (54689) - [+54 9 11] 6799-4797

-----BEGIN GEEK CODE BLOCK-----
Version: 3.1
GCS/IT d-- s:++ a- C+++$ UBL+++$ P(-) L+++$ !E--- W+++$ !N !o K-? !w--- !O
!M-- V? PS+++@ !PE Y+(++) PGP++ !t--- !5 X++ R(+) tv--? b- DI D-- G e@ h>++
r+++(-) y+++>+++++
------END GEEK CODE BLOCK------
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.nginx.org/pipermail/nginx/attachments/20120517/4c43978d/attachment.html>