Vagrant(Virtualbox)/AMI Parity

Hello,

My team is going towards this development workflow: Develop locally on a vagrant VM using test kitchen with chef. Once we're good with that we push to CI which runs the same test-kitchen scripts, but against ec2 in AWS. Ideally our vagrant base box (built using packer from the rhel-server 7.2 x86_64 dvd iso) would be extremely similar, if not the exact same as the base RHEL AMI.

The question is: What's the best way to start from an ISO and run the kickstart in such a way as to end up with a VM that looks as close as possible to the published AMI?

OR

Should we instead start from the ISO, KS it however we want, and then publish that as a private AMI in amazon?

Thanks!