Terraform state is a database kept by Terraform to help it reconcile Terraform resource dependencies, and reconcile between Terraform code and the actual state on the target infrastructure. For example, in the state, Terraform expects to find an entry that matches your AWS resource defining a Route53 record and in your Terraform code. Whether or not the entry exits determines if Terraform will make a change or not.
Here's what I've learned so far using Terraform and its modules. I've just scratched the surface so test and research on your own.
Docker has command line programs, but they are not well suited to automation. Return values and pars-able output are both lacking, but there is an API that you can use instead. The Dockerd api can listen on a local socket or even a remote accessible port, but in these examples I'll show local socket only.
You can reboot and reconnect to your hosts between Ansible tasks.
Cloud Foundry is an open source platform as a service product owned by Pivotal Software. CF allows you to deploy applications to containers on AWS, Azue, VMware vSphere, and others.