nginx - Forward requests to another proxy - nginx

Question

So, I have a third party proxy (probably under squid) which will only accept connections from one of my IP's, but I need to be able to access it from a variety of IPs.
So I'm trying to put a nginx to forward requests to this proxy. I know nginx can forward request like this:
location / {
proxy_pass http://$http_host$uri$is_args$args;
}
This would work if I needed nginx to forward requests directly to the target site, but I need it to pass it to proxy X first. I tried this:
upstream myproxy {
server X.X.X.X:8080;
}
location / {
proxy_pass http://myproxy$uri$is_args$args; // also tried: http://myproxy$http_host$uri$is_args$args
}
But I get "(104) Connection reset by peer". I guess because nginx is proxying like this:
GET /index.html HTTP/1.1
Host: www.targetdomain.com.br
But I need it to proxy like this:
GET http://www.targetdomain.com.br/index.html HTTP/1.1

Answer 1

I found out that this works:
http {
# resolver 8.8.8.8; # Needed if you use a hostname for the proxy
server_name ~(?<subdomain>.+)\.domain\.com$;
server {
listen 80;
location / {
proxy_redirect off;
proxy_set_header Host $subdomain;
proxy_set_header X-Forwarded-Host $http_host;
proxy_pass "http://X.X.X.X:8080$request_uri";
}
}
}
You need to use resolver if X.X.X.X is a hostname and not an IP.
Check https://github.com/kawanet/nginx-forward-proxy/blob/master/etc/nginx.conf for more tricks.
EDIT: also check nginx server_name wildcard or catch-all and http://nginx.org/en/docs/http/ngx_http_core_module.html#var_server_name