nginx-routes/default.nginx.conf

events {}

stream {
    server {
        set $nginx_proxy_source_port '';
        set $nginx_proxy_source_address '';

        content_by_lua_block {
             ngx.var.nginx_proxy_source_port = os.getenv("$NGINX_PROXY_SOURCE_PORT");
             ngx.var.nginx_proxy_source_address = os.getenv("$NGINX_PROXY_SOURCE_ADDRESS");
        }

        listen $nginx_proxy_source_port;
        proxy_pass $nginx_proxy_source_address;
    }
}