Since vbox guest properties are proving to be less reliable than we had
hoped, bring back the static config parsing mechanism for finding a
guest IP to hand to NFS. If we find a static IP (or set of IPs) we'll
use that instead of trying to probe guest properties.
This retains NFS support for DHCP interfaces while regaining the
reliability that we previously had when static IPs were required.
Previously, we required a host-only interface with a static IP for NFS
to work in VirtualBox, because we needed access to the guest's IP in
order to properly configure mount commands.
After boot, VirtualBox exposes the IP addresses of a guest's network
adapters via the "guestproperty" interface.
This adds support for reading VirtualBox guest properties to the
VirtualBox driver and utilizes that support to prepare NFS settings,
which removes the necessity for a static IP for NFS to work.
In this commit we also start building out scaffolding for unit testing
vbox actions and drivers.
Test plan:
- Prepare a Vagrantfile with the following:
* private network with type: :dhcp
* synced folder with nfs: true
- Boot a VM from this Vagrantfile using the virtualbox provider
- Machine should boot successfully with working synced folder
