I want to improve the fault-tolerance of my application, which is running on EC2 instances behind a load balancer (ELB). How do I use Auto Scaling to do that?
If you have a preexisting Elastic Load Balancing load balancer, you can create an Auto Scaling group to automatically terminate unhealthy instances and launch new, healthy ones. In addition to improving the fault tolerance of your application, Auto Scaling can be configured to dynamically scale up your application in response to demand.
You can create an Auto Scaling group that launches copies of instances you’ve already configured, or create a launch configuration that uses an Amazon Machine Image (AMI) instead. After you create the Auto Scaling group, attach your load balancer to it.
Note: Make sure to create your Auto Scaling group in the same region and Availability Zone as your load balancer.