!! Rough notes for now, expand later.

Ansible layout

• Global defaults in group_vars/all.yml ** This is where env-vars should be converted to Ansible vars. It also acts as a required-env list. ** The CF env is usually stored in /etc/atl. The script bin/ansible-with-atl-env will run Ansible with that environment set.
• Runtime information about the EC2 environment can be injected by depending on aws_common in a role's meta/main.yml (or adding it to the playbook before the requiring role.