Better logging in the SaneDefaults middleware

lib/vagrant/action/vm/sane_defaults.rb

@@ -1,3 +1,5 @@
+require "log4r"
+
 module Vagrant
   module Action
     module VM
@@ -6,10 +8,15 @@ module VM
       # behavior.
       class SaneDefaults
         def initialize(app, env)
+          @logger = Log4r::Logger.new("vagrant::action::vm::sanedefaults")
           @app = app
         end
 
         def call(env)
+          # Set the env on an instance variable so we can access it in
+          # helpers.
+          @env = env
+
           # Enable the host IO cache on the sata controller. Note that
           # if this fails then its not a big deal, so we don't raise any
           # errors. The Host IO cache vastly improves disk IO performance
@@ -19,18 +26,31 @@ def call(env)
             "--name", "SATA Controller",
             "--hostiocache", "on"
           ]
-          env[:vm].driver.execute_command(command)
+          attempt_and_log(command, "Enabling the Host I/O cache on the SATA controller...")
 
           # Enable the DNS proxy while in NAT mode.  This shields the guest
           # VM from external DNS changs on the host machine.
           command = [
             "modifyvm", env[:vm].uuid,
             "--natdnsproxy1", "on"
           ]
-          env[:vm].driver.execute_command(command)
+          attempt_and_log(command, "Enable the NAT DNS proxy on adapter 1...")
 
           @app.call(env)
         end
+
+        protected
+
+        # This is just a helper method that executes a single command, logs
+        # the given string to the log, and also includes the exit status in
+        # the log message.
+        #
+        # @param [Array] command Command to run
+        # @param [String] log Log message to write.
+        def attempt_and_log(command, log)
+          result = @env[:vm].driver.execute_command(command)
+          @logger.info("#{log} (exit status = #{result.exit_code})")
+        end
       end
     end
   end