This project is an example of how Vagrant and a virtualization provider (e.g. VirtualBox) can be used in the enterprise.
The 3 folders would normally be split in separate projects:
- one instance of the enterprise-level project, maintained by the organization's infrastructure team
- N instances of the team-level project, each one maintained by a different delivery team, with possibly different provisioning needs.
- M instances of the project-level Vagrantfile, located alongside the source code of the deployable module.
You can read the detailed description of this project in this blog post.