Change http_host fastcgi param with nginx

Question

Context: I've got an application that run under a given domain. But in some cases I need to run it under another domain than the domain it expect (I also change potentially the port).

I'm trying to custom the fastcgi_param HTTP_HOST, but the application still receive the "real" one.

Here is what I tried as configuration:

location ~ [^/]\.php(/|$) { fastcgi_split_path_info ^(.+?\.php)(/.*)$; fastcgi_pass php:9000; fastcgi_index app.php; fastcgi_param SCRIPT_FILENAME /app/web$fastcgi_script_name; fastcgi_intercept_errors on; include fastcgi_params; fastcgi_param SERVER_NAME my-app.com; fastcgi_param HTTP_HOST my-app.com; } 

There's many problems:

1. The port is not specified in HTTP_HOST, is there a way to set only the host? (maybe a set a variable that will be use for definition of the param)
2. This does not work at all, finally "my-app.com" is not transmitted; why?

Note: this is based on nginx docker image.

Answer 1

Found the problem:

I have many server part in my nginx configuration. I didn't mention it because I though nginx take the last if no match. But it's actually the complete opposite. I put the right server part as first one and it's working.