I'd like to add, if using Elastic Beanstalk, don't directly attach an RDS instance when creating the environment. If you do, you won't be able to destroy your environment without also deleting the RDS instance. Instead, create the RDS instance separately, and just add the proper security group for the environment to be able to access the host. Then you can easily create a new eb environment with any config changes (there are some config changes you can't make to an eb environment without creating a new one from scratch) and then connect to your existing db.