This is an authorized repost of http://zipkid.eu/
Back in 2012 Ohad Levy wrote an excellent blog post on this subject. The concepts and steps to perform he explains are still mainly correct and relevant but the UI has changed enough to justify a new post.
This is a companion discussion topic for the original entry at https://theforeman.org/2016/02/ec2-provisioning-using-foreman-update.html