A role is defined as a set of components to achieve a feature.
A role is so composed of one or several applications, each
deployed by a component.
A component is a collection of deployment script and files to deploy.
This gives the following roles/<role>/<component> tree:
. ├── roles │ ├── mailserver │ │ └── systemd-unit │ │ └── files │ └── paas-docker │ └── systemd-unit │ └── files