Instead of storing an "active" hash in the local_data of an Environment,
we now place the ID of a machine in the "id" file of the machine data
directory. This file is read upon re-instantiation in order to load the
proper state.
The local data path is set to the `ROOT_DIR/.vagrant` by default and is
a directory where Vagrant can store environment-local state. This can be
overriden on a per-Environment basis using the `local_data_path`
option.
The issue here is that when a middleware failed and a recovery sequence
started, it would halt at the "call" step because the "Call" didn't
properly recover the child sequence.
An additional issue was that a Warden had no "recover" method, meaning
embedded Wardens wouldn't recover their stacks properly.
This works by registering a `config` with `:provider => true` with the
same name as your provider. Vagrant will then automatically configure
the provider when `config.vm.provider` is used.
Boxes are provider-specific, and we don't know the provider until
Environment#machine is called, so we need to build up the machine
configuration during this time.
This will eventually replace the Environment#vms method. Because of the
introduction of providers, the environment doesn't know what the backing
of the machines will be (and they're _machines_ now, not _vms_).
Instead, users of Environment will now call `#machine` on the
environment to retrieve a machine with the given backing provider as it
needs it.
This is done by calling the `upgrade` method on the _old_ configuration
classes. The old configuration classes are given the complete new
configuration and can set whatever settings they need to on it.
These are classes that use NO core classes of Vagrant, and are therefore
safe to load for upgrades. i.e. a V2 core can load a V1 config class
that is deemed upgrade safe without crashing Vagrant.
Before we were manually going over every plugin and getting each piece,
all over the place. Now we have a central manager that will give us all
the pieces we want. There is still some cleanup to do here but this is
much better overall.
