Use Elastic Load Balancing with Engine Yard Cloud
Engine Yard's Elastic Load Balancer (ELB) feature allows you to use the Amazon Elastic Load Balancer service with your AWS environments in the cloud.
The load balancer distributes requests to instances (servers) in multiple availability zones (AZs) in a way that minimizes the risk of overloading one single instance. And if an entire AZ goes offline, the load balancer routes traffic to instances in another AZ. The Elastic Load Balancer also monitors the health of instances registered with the load balancer and sends requests only to the healthy instances. If an instance becomes unhealthy, the Elastic Load Balancer stops sending traffic to that instance and spreads the load across remaining healthy cloud instances.
The Elastic Load Balancer takes some of the load off the app_master (which, by default, balances traffic across all cloud instances using HAProxy). The load balancer reveals the client's IP address with HTTPS connections (with HAProxy, this requires a stunnel configuration). Additionally, the Elastic Load Balancer allows for multiple SSL certificates in an environment (with HAProxy you must use wildcard certificates; with ELB you can use certificates for multiple domains).
Finally, the Elastic Load Balancer allows a cloud environment to run multiple apps with SSL (when SSL is load balancer terminated).