Getting FastCGI Upstream Information

[Arie Karhendana]

Hi all,

I think this is not nginx specific question per se, but seeing all
experts here, maybe this list is the right place to start.

We have an nginx & PHP FastCGI configuration, where nginx is run on
different server than the PHP backends. We employ upstream
load-balancing scheme like this:

upstream upstream-php {
        fair;
        server 10.0.0.41:9000;
        server 10.0.0.42:9000;
        .....
}

We want to know the address of PHP upstream that currently serve the
request, and send it to the backend using fastcgi_param. We tried
adding this to the configuration:

fastcgi_param UPSTREAM_ADDR $upstream_addr;

But the UPSTREAM_ADDR param is always empty.

Maybe I'm doing it wrong? Any clues?

TIA,
-- 
Arie Karhendana