For this gist I assume you are working with an Elastic Beanstalk Application Environment set up with an Application Load Balancer. I also assume you are wanting to point a subdomain of your custom domain to your EB application. If you have a different setup then this process may not work for you, though there may still be some useful parts. As with most guides on the internet, your mileage may vary.
- A running application environment in Elastic Beanstalk
- Access to modify the DNS records on your custom domain
- Access to AWS Console with the relevant IAM permissions