upstream my_backend_servers {
    server 127.0.0.1:8001;
    server 127.0.0.1:8002;
}

server {
    listen 8080;
    server_name localhost;

    location / {
        proxy_pass http://my_backend_servers;
        add_header X-Upstream-Server $upstream_addr always;
        add_header Cache-Control "no-store" always;
    }
}