The --provider flag for `up` now actually does something.

lib/vagrant/plugin/v2/command.rb

@@ -62,6 +62,9 @@ module Vagrant
         #
         # @param [String] name The name of the VM. Nil if every VM.
         # @param [Hash] options Additional tweakable settings.
+        # @option options [Symbol] :provider The provider to back the
+        #   machines with. All machines will be backed with this
+        #   provider. If none is given, a sensible default is chosen.
         # @option options [Boolean] :reverse If true, the resulting order
         #   of machines is reversed.
         # @option options [Boolean] :single_target If true, then an
@@ -78,7 +81,7 @@ module Vagrant
           names = [names] if !names.is_a?(Array)
 
           # The provider that we'll be loading up.
-          provider = @env.default_provider
+          provider = (options[:provider] || @env.default_provider).to_sym
 
           # First determine the proper array of VMs.
           machines = []

plugins/commands/up/command.rb

@@ -19,7 +19,7 @@ module VagrantPlugins
 
           o.on("--provider provider", String,
                "Back the machine with a specific provider.") do |provider|
-            options["provider"] = provider
+            options[:provider] = provider
           end
         end
 
@@ -29,7 +29,7 @@ module VagrantPlugins
 
         # Go over each VM and bring it up
         @logger.debug("'Up' each target VM...")
-        with_target_vms(argv) do |machine|
+        with_target_vms(argv, :provider => options[:provider]) do |machine|
           machine.action(:up)
         end
 

test/unit/vagrant/plugin/v2/command_test.rb

@@ -107,6 +107,17 @@ describe Vagrant::Plugin::V2::Command do
       instance.with_target_vms("foo") { |vm| vms << vm }
       vms.should == [foo_vm]
     end
+
+    it "yields the given VM with proper provider if given" do
+      foo_vm = double("foo")
+      provider = :foobarbaz
+
+      environment.stub(:machine).with(:foo, provider).and_return(foo_vm)
+
+      vms = []
+      instance.with_target_vms("foo", :provider => provider) { |vm| vms << vm }
+      vms.should == [foo_vm]
+    end
   end
 
   describe "splitting the main and subcommand args" do