Nginx Problem with fastcgi_param

Erik Osterman e at
Wed May 14 03:58:09 MSD 2008

 From my past work with the FastCGI protocol, I believe all the NV pairs 
(params) set using the FastCGI protocol are available to PHP in the 
_SERVER global. Also, HTTP_HOST is not supposed to be derived by PHP, as 
it reflects the client-side "Host:" header (versus SERVER_NAME which is 
the Nginx configured host), so the only way to pass it to PHP would be 
through the FCGI protocol (since raw headers are not passed).

You're entirely correct though that SERVER_NAME gets set with whatever 
we pass, so we'll have to adjust our stuff for that in the meanwhile.



mike wrote:
> I don't believe HTTP_HOST is one you set. I think it's determined by PHP
> This is what I set (SERVER_NAME in nginx seems to be different than HTTP_HOST)
> fastcgi_param  SERVER_NAME        $http_host;
> Then the people's scripts that were using $_SERVER['SERVER_NAME'] work
> properly. Typically I try to use $_SERVER['HTTP_HOST'] ...
> $http_host is a variable in nginx, but I think HTTP_HOST in PHP is
> being set on its own. not via a param you pass. could be a possible
> "bug" in PHP to say "if I want to override default PHP behavior for
> HTTP_HOST, I should be able to do it"
> Could this be resolved with $_SERVER['SERVER_NAME'] in your PHP code?
> and/or in combination with changing it to be $http_host in the fastcgi
> params?
> On 5/13/08, Erik Osterman <e at> wrote:
>> We've been running Nginx(0.5.33)+FastCGI(php-cgi 5.1.6) on Fedora 6 for 1
>> week now and very happy with it. Before this, we were using Nginx as
>> strictly a HTTP load balancer. I have encountered an issue migrating to
>> FastCGI, which is that HTTP_HOST cannot be set using fastcgi_param. It seems
>> that no matter what I pass (e.g., Nginx is not honoring it,
>> passing the real HTTP_HOST of the request instead. The other variables like
>> SCRIPT_FILENAME and SCRIPT_NAME are getting set properly if I change them.
>> Is there something I am doing wrong or is this a known issue?
>> Best,
>> Erik

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