Nginx

# ln -s /etc/nginx/sites-available/example.com /etc/nginx/sites-enabled/example.com

server {
        listen          80;
        server_name     www.domain1.com;
        access_log      logs/domain1.access.log main;
        location / {
            index index.html;
            root  /var/www/domain1.com/htdocs;
        }
    }

http {
    upstream myproject {
        server 127.0.0.1:8000 weight=3;
        server 127.0.0.1:8001;
        server 127.0.0.1:8002;    
        server 127.0.0.1:8003;
    }
    server {
        listen 80;
        server_name www.domain.com;
        location / {
            proxy_pass http://myproject;
        }
    }
}