Add the Environment#machine method

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.

lib/vagrant/environment.rb

@@ -129,6 +129,38 @@ module Vagrant
       @_boxes ||= BoxCollection.new(boxes_path)
     end
 
+    # This returns a machine with the proper provider for this environment.
+    # The machine named by `name` must be in this environment.
+    #
+    # @param [Symbol] name Name of the machine (as configured in the
+    #   Vagrantfile).
+    # @param [Symbol] provider The provider that this machine should be
+    #   backed by.
+    # @return [Machine]
+    def machine(name, provider)
+      vm_config = config.for_vm(name)
+      if !vm_config
+        raise Errors::MachineNotFound, :name => name, :provider => provider
+      end
+
+      provider_cls = Vagrant.plugin("2").manager.providers[provider]
+      if !provider_cls
+        raise Errors::ProviderNotFound, :machine => name, :provider => provider
+      end
+
+      box = boxes.find(vm_config.vm.box, provider)
+      Machine.new(name, provider_cls, vm_config, box, self)
+    end
+
+    # This returns a list of the configured machines for this environment.
+    # Each of the names returned by this method is valid to be used with
+    # the {#machine} method.
+    #
+    # @return [Array<Symbol>] Configured machine names.
+    def machine_names
+      config.vms
+    end
+
     # Returns the VMs associated with this environment.
     #
     # @return [Hash<Symbol,VM>]

lib/vagrant/errors.rb

@@ -234,6 +234,10 @@ module Vagrant
       error_key(:machine_guest_not_ready)
     end
 
+    class MachineNotFound < VagrantError
+      error_key(:machine_not_found)
+    end
+
     class MultiVMEnvironmentRequired < VagrantError
       status_code(5)
       error_key(:multi_vm_required)
@@ -314,6 +318,10 @@ module Vagrant
       error_key(:dotfile_error, "vagrant.actions.vm.persist")
     end
 
+    class ProviderNotFound < VagrantError
+      error_key(:provider_not_found)
+    end
+
     class PluginLoadError < VagrantError
       status_code(81)
       error_key(:plugin_load_error)

plugins/commands/up/command.rb

@@ -12,9 +12,15 @@ module VagrantPlugins
       def execute
         options = {}
         opts = OptionParser.new do |o|
-          o.banner = "Usage: vagrant up [vm-name] [--[no-]provision] [-h]"
+          o.banner = "Usage: vagrant up [vm-name] [--[no-]provision] [--provider provider] [-h]"
           o.separator ""
+
           build_start_options(o, options)
+
+          o.on("--provider provider", String,
+               "Back the machine with a specific provider.") do |provider|
+            options["provider"] = provider
+          end
         end
 
         # Parse the options

plugins/kernel_v2/config/vm.rb

@@ -163,7 +163,6 @@ module VagrantPlugins
           elsif type == :hostonly
             # Validate the host-only network
             ip      = args[0]
-            options = args[1] || {}
 
             if !ip
               errors.add(I18n.t("vagrant.config.vm.network_ip_required"))

templates/locales/en.yml

@@ -89,6 +89,9 @@ en:
         Guest-specific operations were attempted on a machine that is not
         ready for guest communication. This should not happen and a bug
         should be reported.
+      machine_not_found: |-
+        The machine with the name '%{name}' was not found configured for
+        this Vagrant environment.
       multi_vm_required: |-
         A multi-vm environment is required for name specification to this command.
       multi_vm_target_required: |-
@@ -105,6 +108,9 @@ en:
         for you but VirtualBox only allows forwarded ports to change if the VM is
         powered off. Therefore, please reload your VM or halt the other running
         VMs to continue.
+      provider_not_found: |-
+        The provider '%{provider}' could not be found, but was requested to
+        back the machine '%{machine}'. Please use a provider that exists.
       scp_permission_denied: |-
         Failed to upload a file to the guest VM via SCP due to a permissions
         error. This is normally because the user running Vagrant doesn't have

test/unit/vagrant/environment_test.rb

@@ -236,4 +236,71 @@ VF
       instance.ui.should be_kind_of(CustomUI)
     end
   end
+
+  describe "getting a machine" do
+    it "should return a machine object with the correct provider" do
+      # Create a provider
+      foo_provider = Class.new(Vagrant.plugin("2", :provider))
+      register_plugin("2") do |p|
+        p.provider("foo") { foo_provider }
+      end
+
+      # Create the configuration
+      isolated_env = isolated_environment do |e|
+        e.vagrantfile(<<-VF)
+Vagrant.configure("2") do |config|
+  config.vm.box = "base"
+  config.vm.define "foo"
+end
+VF
+      end
+
+      # Verify that we can get the machine
+      env = isolated_env.create_vagrant_env
+      machine = env.machine(:foo, :foo)
+      machine.should be_kind_of(Vagrant::Machine)
+      machine.name.should == :foo
+      machine.provider.should be_kind_of(foo_provider)
+    end
+
+    it "should raise an error if the VM is not found" do
+      expect { instance.machine("i-definitely-dont-exist", :virtualbox) }.
+        to raise_error(Vagrant::Errors::MachineNotFound)
+    end
+
+    it "should raise an error if the provider is not found" do
+      expect { instance.machine(:default, :lol_no) }.
+        to raise_error(Vagrant::Errors::ProviderNotFound)
+    end
+  end
+
+  describe "getting machine names" do
+    it "should return the default machine if no multi-VM is used" do
+      # Create the config
+      isolated_env = isolated_environment do |e|
+        e.vagrantfile(<<-VF)
+Vagrant.configure("2") do |config|
+end
+VF
+      end
+
+      env = isolated_env.create_vagrant_env
+      env.machine_names.should == [:default]
+    end
+
+    it "should return the machine names in order" do
+      # Create the config
+      isolated_env = isolated_environment do |e|
+        e.vagrantfile(<<-VF)
+Vagrant.configure("2") do |config|
+  config.vm.define "foo"
+  config.vm.define "bar"
+end
+VF
+      end
+
+      env = isolated_env.create_vagrant_env
+      env.machine_names.should == [:foo, :bar]
+    end
+  end
 end