Routing traffic in nginx according to received header

Nadav Aviv asked:

I’m trying to route traffic in my nginx proxy according to a received header.

My infrastructure is built in a way that traffic is being sent to the proxy with a header that contains part of the address that I want to route to.

Here is my code:

upstream target {
    server $http_address.domain.com max_fails=3 fail_timeout=60;
}

server {
    listen 80 default_server;
    
    location / {
        proxy_pass http://target;
        proxy_redirect off;
        proxy_http_version 1.1;
    }
}

Unfortunately I’m getting the following error when starting nginx:

host not found in upstream "$http_address.domain.com"

Is there any way I can dynamically edit the server’s target url according to a given header?

Thanks.