Amazon EC2 autoscaling instances with elastic IPs

Question

Is there any way to make new instances added to an autoscaling group associate with an elastic IP? I have a use case where the instances in my autoscale group need to be whitelisted on remote servers, so they need to have predictable IPs.

I realize there are ways to do this programmatically using the API, but I'm wondering if there's any other way. It seems like CloudFormation may be able to do this.

Answer 1

You can associate an Elastic IP to ASG instances using manual or scripted API calls just as you would any other instance -- however, there is no automated way to do this. ASG instances are designed to be ephemeral/disposable, and Elastic IP association goes against this philosophy.

To solve your problem re: whitelisting, you have a few options:

1. If the system that requires predictable source IPs is on EC2 and under your control, you can disable IP restrictions and use EC2 security groups to secure traffic instead
2. If the system is not under your control, you can set up a proxy server with an Elastic IP and have your ASG instances use the proxy for outbound traffic
3. You can use http://aws.amazon.com/vpc/ to gain complete control over instance addressing, including network egress IPs -- though this can be time consuming