Truth should guide your configuration management tools. Truth in this case is: what machines you have, properties of those machines, roles for those machines, etc. For example “foo-1.a.example.com is a webserver” is a piece of truth. Where and how you store truth is up to you and out of scope for this post. My goal is to have truth steer everything about my infrastructure. Roles, jobs, and even long-term one-offs get put into the truth source (like a machine role, etc).