upstream piston {
    server 127.0.0.1:2001;
    server 127.0.0.1:2002;
    server 127.0.0.1:2003;
    server 127.0.0.1:2004;
    server 127.0.0.1:2005;
    server 127.0.0.1:2006;
    server 127.0.0.1:2007;
    server 127.0.0.1:2008;
    server 127.0.0.1:2009;
    server 127.0.0.1:2010;
}

server {
    listen 80;

    location / {
        proxy_pass http://piston;
    }
}