Atmos provides a layer of organization on top of terraform for creating cloud system architectures, initially focused on doing so with Amazon Web Services. It handles all the details of defining and maintaining a complete system using terraform so you can focus on your application, yet still preserve the ability to evolve your infrastructure over time. The atmos runtime is free and open-source, with a business friendly license (Apache). It provides some basic recipes to help get you going with a service oriented architecture implemented with AWS Elastic Container Services.
To try it out, follow the installation instructions and quickstart on the github page
In a nutshell, you supply a docker image of your app (green), and atmos will enable the rest of the architecture below, giving you full control to change it over time.