Systems can now respond to `distro_dispatch` to return specific distro systems

lib/vagrant/systems/base.rb

@@ -27,6 +27,15 @@ module Vagrant
         @vm = vm
       end
 
+      # This method is automatically called when the system is available (when
+      # Vagrant can successfully SSH into the machine) to give the system a chance
+      # to determine the distro and return a distro-specific system.
+      #
+      # **Warning:** If a return value which subclasses from {Base} is
+      # returned, Vagrant will use it as the new system instance for the
+      # class.
+      def distro_dispatch; end
+
       # Halt the machine. This method should gracefully shut down the
       # operating system. This method will cause `vagrant halt` and associated
       # commands to _block_, meaning that if the machine doesn't halt

lib/vagrant/systems/linux.rb

@@ -1,32 +1,9 @@
+require 'vagrant/systems/linux/error'
+require 'vagrant/systems/linux/config'
+
 module Vagrant
   module Systems
-    # A general Vagrant system implementation for "linux." In general,
-    # any linux-based OS will work fine with this system, although its
-    # not tested exhaustively. BSD or other based systems may work as
-    # well, but that hasn't been tested at all.
-    #
-    # At any rate, this system implementation should server as an
-    # example of how to implement any custom systems necessary.
     class Linux < Base
-      # A custom config class which will be made accessible via `config.linux`
-      # This is not necessary for all system implementers, of course. However,
-      # generally, Vagrant tries to make almost every aspect of its execution
-      # configurable, and this assists that goal.
-      class LinuxConfig < Vagrant::Config::Base
-        configures :linux
-
-        attr_accessor :halt_timeout
-        attr_accessor :halt_check_interval
-
-        def initialize
-          @halt_timeout = 30
-          @halt_check_interval = 1
-        end
-      end
-
-      #-------------------------------------------------------------------
-      # Overridden methods
-      #-------------------------------------------------------------------
       def halt
         vm.env.ui.info I18n.t("vagrant.systems.linux.attempting_halt")
         vm.ssh.execute do |ssh|
@@ -111,11 +88,5 @@ module Vagrant
         end
       end
     end
-
-    class Linux < Base
-      class LinuxError < Errors::VagrantError
-        error_namespace("vagrant.systems.linux")
-      end
-    end
   end
 end

lib/vagrant/systems/linux/config.rb

@@ -0,0 +1,21 @@
+module Vagrant
+  module Systems
+    class Linux < Vagrant::Systems::Base
+      # A custom config class which will be made accessible via `config.linux`
+      # This is not necessary for all system implementers, of course. However,
+      # generally, Vagrant tries to make almost every aspect of its execution
+      # configurable, and this assists that goal.
+      class LinuxConfig < Vagrant::Config::Base
+        configures :linux
+
+        attr_accessor :halt_timeout
+        attr_accessor :halt_check_interval
+
+        def initialize
+          @halt_timeout = 30
+          @halt_check_interval = 1
+        end
+      end
+    end
+  end
+end

lib/vagrant/systems/linux/error.rb

@@ -0,0 +1,9 @@
+module Vagrant
+  module Systems
+    class Linux < Vagrant::Systems::Base
+      class LinuxError < Errors::VagrantError
+        error_namespace("vagrant.systems.linux")
+      end
+    end
+  end
+end

lib/vagrant/vm.rb

@@ -3,7 +3,6 @@ module Vagrant
     include Vagrant::Util
 
     attr_reader :env
-    attr_reader :system
     attr_reader :name
     attr_reader :vm
 
@@ -41,6 +40,8 @@ module Vagrant
         # Load the associated system.
         load_system!
       end
+
+      @loaded_system_distro = false
     end
 
     # Loads the system associated with the VM. The system class is
@@ -48,8 +49,8 @@ module Vagrant
     # can be found by reading the documentation on {Vagrant::Systems::Base}.
     #
     # **This method should never be called manually.**
-    def load_system!
-      system = env.config.vm.system
+    def load_system!(system=nil)
+      system ||= env.config.vm.system
 
       if system.is_a?(Class)
         @system = system.new(self)
@@ -65,6 +66,19 @@ module Vagrant
       end
     end
 
+    # Returns the system for this VM, loading the distro of the system if
+    # we can.
+    def system
+      if !@loaded_system_distro && created? && vm.running?
+        # Load the system distro for the first time
+        result = @system.distro_dispatch
+        load_system!(result)
+        @loaded_system_distro = true
+      end
+
+      @system
+    end
+
     # Access the {Vagrant::SSH} object associated with this VM.
     # On the initial call, this will initialize the object. On
     # subsequent calls it will reuse the existing object.

test/vagrant/vm_test.rb

@@ -25,6 +25,7 @@ class VMTest < Test::Unit::TestCase
     setup do
       @vm_name = "foo"
       @mock_vm = mock("vm")
+      @mock_vm.stubs(:running?).returns(false)
       @vm = Vagrant::VM.new(:env => @env, :vm => @mock_vm, :name => @vm_name)
       @mock_vm.stubs(:uuid).returns("foo")
     end
@@ -96,11 +97,14 @@ class VMTest < Test::Unit::TestCase
         }
       end
 
-      context "with a class" do
-        class FakeSystemClass
-          def initialize(vm); end
-        end
+      should "load the given system if specified" do
+        fake_class = Class.new(Vagrant::Systems::Base)
 
+        assert_nothing_raised { @vm.load_system!(fake_class) }
+        assert @vm.system.is_a?(fake_class)
+      end
+
+      context "with a class" do
         should "initialize class if given" do
           @vm.env.config.vm.system = Vagrant::Systems::Linux
 
@@ -109,7 +113,7 @@ class VMTest < Test::Unit::TestCase
         end
 
         should "raise error if class has invalid parent" do
-          @vm.env.config.vm.system = FakeSystemClass
+          @vm.env.config.vm.system = Class.new
           assert_raises(Vagrant::Errors::VMSystemError) {
             @vm.load_system!
           }
@@ -140,6 +144,30 @@ class VMTest < Test::Unit::TestCase
           }
         end
       end
+
+      context "loading the distro" do
+        setup do
+          @vm.vm.stubs(:running?).returns(true)
+        end
+
+        should "not replace the distro if it is nil" do
+          @vm.env.config.vm.system = Class.new(Vagrant::Systems::Base)
+
+          @vm.load_system!
+          assert @vm.system.is_a?(@vm.env.config.vm.system)
+        end
+
+        should "replace the distro if it is not nil" do
+          @vm.env.config.vm.system = Class.new(Vagrant::Systems::Base) do
+            def distro_dispatch
+              :linux
+            end
+          end
+
+          @vm.load_system!
+          assert @vm.system.is_a?(Vagrant::Systems::Linux)
+        end
+      end
     end
 
     context "uuid" do