Like in the (remote) `ansible` provisioner, it is preferred to pass the directory that contains the generated inventory file. This way, advanced inventory usages can be achieved by adding more inventory files into the same directory. Related to #2103 and #6500 [ci skip]
Vagrant Core Plugins
These are plugins that ship with Vagrant. Vagrant core uses its own plugin system to power a lot of the core pieces that ship with Vagrant. Each plugin will have its own README which explains its specific role.