Get network interface Nginx is receiving request on

Question

I have a server with multiple network interfaces, and I want to write a proxy server, which would listen on all of these IPs.

My config so far:

server {
    listen          111.111.111.111:40000;
    listen          111.111.111.222:40000;
    location / {
        resolver    8.8.8.8;
        proxy_bind  <listen interface here>;
        proxy_pass  http://$host;
    }
}

If I omit proxy_bind directive, Nginx sends request from the default IP, not the one I send request to.

Is it possible to fix this? If I could get the IP, request came to, it would solve my problem.

Answer 1

Have you tried to:

proxy_bind $server_addr;

I'm not 100% sure if that variable is available within a proxy configuration. But it should contain address of the specific connection.