title: On AWS, why should Packer be required to generate AMIs, since ami_from_instance exist in terraform
body: <p>Terraform allows provisionning aws infrastructures with custom ansible scripts.</p>
  
  <p>Since the function <a href="https://www.terraform.io/docs/providers/aws/r/ami_from_instance.html" rel="nofollow noreferrer">ami_from_instance</a> from terraform, 
  allow convert an Instance into an AMI, and <a href="https://www.terraform.io/docs/providers/aws/r/instance.html" rel="nofollow noreferrer">aws_instance</a> the opposit.
  I am quite new to that tools and I might not understand their subtilities but why should the common pattern of using Packer to generate the ami instanciated by Terraform be used ?</p>