Archivo de configuración de nginx que uso para balancear un servicio

balanceador.conf

 upstream balanceador {
    server srv02:9001;
    server srv02:9002;
    server srv02:9003;
}

server {
    server_name balanceador.qbits.mx;

    location / {
      proxy_pass http://balanceador;
    }

    include common/ssl.conf;
    include common/error.conf;
    include common/last.conf;
}