Encrypting data at rest
As a configuration management system or an orchestration engine, Ansible has great power. To wield that power, it is necessary to entrust secret data to Ansible. An automation system that prompts the operator for passwords at each connection is not very efficient —indeed, it's hardly fully automated if you have to sit there and type in passwords over and over! To maximize the power of Ansible, secret data must be written to a file that Ansible can read and from which it can utilize the data.
This creates a risk, though! Your secrets are sitting there on your filesystem in plaintext. This is a physical as well as a digital risk. Physically, the computer could be taken from you and pored over for secret data. Digitally, any malicious software that can break the boundaries set upon it is capable of reading any data to which your user account has access. If you utilize a source control system, the infrastructure that houses the repository is just...