Amazon EC2: Public IP changes at reboot
Solution 1:
An Elastic IP can be assigned to an instance. This is not ephemeral like the Public IP assigned to the instance and thus will be maintained across resizes and can be re-assigned to different instances.
Information on setting this up can be found here: https://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/vpc-ip-addressing.html#vpc-eips