How do you put up a maintenance page for AWS when your instances are behind an ELB?

Question

How do you put up a maintenance page in AWS when you want to deploy new versions of your application behind an ELB? We want to have the ELB route traffic to the maintenance inst

Answer 1

Our deployment process first runs a cloudformation to spun up a ec2 micro instance (Maintenance instance) which copies pre-defined static page from s3 onto the ec2. Cloudformation is supplied with elb's to which micro ec2 instance is attached. Then a script (powershell or cli) is run to remove web instances (ec2) from elb's leaving Maintenance instance.

This way we switch to maintenance instance during deployment process.

In our case, we have two elb's, one for external and the other internal. Our internal elb's will not be updated during this process and is how we have post prod deployment smoke test is done. Once testing is done, we run another script to attach web instances back to elb's and delete the Maintenance stack.