Change boot_mode to a provider config `gui`.

OLD:

config.vm.boot_mode = :gui

NEW:

config.vm.provider :virtualbox do |vb|
  vb.gui = true
end

config/default.rb

@@ -16,7 +16,6 @@ Vagrant.configure("2") do |config|
   config.vm.box_url = nil
   config.vm.base_mac = nil
   config.vm.forward_port 22, 2222, :name => "ssh", :auto => true
-  config.vm.boot_mode = "headless"
   config.vm.guest = :linux
 
   # Share the root folder. This can then be overridden by

plugins/kernel_v1/config/vm.rb

@@ -85,12 +85,16 @@ module VagrantPlugins
       def upgrade(new)
         new.vm.auto_port_range = self.auto_port_range if self.auto_port_range
         new.vm.base_mac        = self.base_mac if self.base_mac
-        new.vm.boot_mode       = self.boot_mode if self.boot_mode
         new.vm.box             = self.box if self.box
         new.vm.box_url         = self.box_url if self.box_url
         new.vm.guest           = self.guest if self.guest
         new.vm.host_name       = self.host_name if self.host_name
 
+        if self.boot_mode
+          # Enable the GUI if the boot mode is GUI.
+          new.vm.providers[:virtualbox].config.gui = (self.boot_mode.to_s == "gui")
+        end
+
         # If we have VM customizations, then we enable them on the
         # VirtualBox provider on the new VM.
         self.customizations.each do |customization|

plugins/kernel_v2/config/vm.rb

@@ -13,7 +13,6 @@ module VagrantPlugins
 
       attr_accessor :auto_port_range
       attr_accessor :base_mac
-      attr_accessor :boot_mode
       attr_accessor :box
       attr_accessor :box_url
       attr_accessor :guest
@@ -122,7 +121,6 @@ module VagrantPlugins
       def validate(env, errors)
         errors.add(I18n.t("vagrant.config.vm.box_missing")) if !box
         errors.add(I18n.t("vagrant.config.vm.box_not_found", :name => box)) if box && !box_url && !env.boxes.find(box, :virtualbox)
-        errors.add(I18n.t("vagrant.config.vm.boot_mode_invalid")) if ![:headless, :gui].include?(boot_mode.to_sym)
         errors.add(I18n.t("vagrant.config.vm.base_mac_invalid")) if env.boxes.find(box, :virtualbox) && !base_mac
 
         shared_folders.each do |name, options|

plugins/providers/virtualbox/action/boot.rb

@@ -9,9 +9,11 @@ module VagrantPlugins
         def call(env)
           @env = env
 
+          boot_mode = @env[:machine].provider_config.gui ? "gui" : "headless"
+
           # Start up the VM and wait for it to boot.
           env[:ui].info I18n.t("vagrant.actions.vm.boot.booting")
-          env[:machine].provider.driver.start(@env[:machine].config.vm.boot_mode)
+          env[:machine].provider.driver.start(boot_mode)
           raise Errors::VMFailedToBoot if !wait_for_boot
 
           @app.call(env)
@@ -41,7 +43,6 @@ module VagrantPlugins
           @env[:ui].error I18n.t("vagrant.actions.vm.boot.failed")
           false
         end
-
       end
     end
   end

plugins/providers/virtualbox/config.rb

@@ -3,8 +3,12 @@ module VagrantPlugins
     class Config < Vagrant.plugin("2", :config)
       attr_reader :customizations
 
+      # If set to `true`, then VirtualBox will be launched with a GUI.
+      attr_accessor :gui
+
       def initialize
         @customizations = []
+        @gui = UNSET_VALUE
       end
 
       # Customize the VM by calling `VBoxManage` with the given

templates/locales/en.yml

@@ -271,7 +271,6 @@ en:
         private_key_missing: "`private_key_path` file must exist: %{path}"
       vm:
         base_mac_invalid: "Base MAC address for eth0/NAT must be set. Contact box maintainer for more information."
-        boot_mode_invalid: "Boot mode must be one of: headless or gui"
         box_missing: "A box must be specified."
         box_not_found: "The box '%{name}' could not be found."
         network_invalid: |-