Add a publisher to package up the generated box

Enabling this post-build step means the wrapper will not destroy the machine,
but the publisher will take over responsibility for that instead.

Related to #10

models/vagrant_builder.rb

@@ -25,6 +25,7 @@ module Vagrant
       end
 
       unless @vagrant.nil?
+        build.env[:vagrant_dirty] = true
         code = @vagrant.primary_vm.channel.send(vagrant_method, @command) do |type, data|
           # type is one of [:stdout, :stderr, :exit_status]
       #   # data is a string for stdout/stderr and an int for exit status
@@ -93,6 +94,7 @@ module Vagrant
       end
 
       listener.info('Provisioning the Vagrant VM.. (this may take a while)')
+      build.env[:vagrant_dirty] = true
       @vagrant.cli('provision')
     end
   end

models/vagrant_publisher.rb

@@ -0,0 +1,46 @@
+require 'rubygems'
+require 'vagrant'
+
+
+module Vagrant
+  class PackagePublisher < Jenkins::Tasks::Publisher
+    display_name "Package Vagrant box"
+
+    attr_accessor :boxname
+    def initialize(attrs)
+      @vagrant = nil
+      @boxname = attrs['boxname']
+    end
+
+    def prebuild(build, listener)
+      # To run packaging, we need to own the destroy of the box
+      build.env[:vagrant_disable_destroy] = true
+    end
+
+    def perform(build, launcher, listener)
+      @vagrant = build.env[:vagrant]
+      if @vagrant.nil?
+        built.halt "OH CRAP! I don't seem to have a Vagrant instance in the publisher"
+      end
+
+      unless build.env[:vagrant_dirty]
+        listener.info("It doesn't appear any changes were made inside the Vagrant VM")
+        listener.info("I'm going to save us all a lot of grief and skip packaging it up then")
+        return
+      end
+
+      name = @boxname
+      if name.nil? or name.empty?
+        name = 'package.box'
+      end
+      unless name.end_with? '.box'
+        name = "#{name}.box"
+      end
+
+      listener.info("Preparing to export the current Vagrant box to a file named: #{name}")
+      output = File.expand_path(File.join(build.workspace.to_s, name))
+      @vagrant.cli('package', '--output', output)
+      @vagrant.cli('destroy', '-f')
+    end
+  end
+end

models/vagrant_wrapper.rb

@@ -68,12 +68,20 @@ module Vagrant
       listener.info "Vagrant box is online, continuing with the build"
 
       build.env[:vagrant] = @vagrant
+      # We use this variable to determine if we have changes worth packaging,
+      # i.e. if we have actually done anything with the box, we will mark it
+      # dirty and can then take further action based on that
+      build.env[:vagrant_dirty] = false
     end
 
     # Called some time when the build is finished.
     def teardown(build, listener)
-      listener.info "Build finished, destroying the Vagrant box"
-      unless @vagrant.nil?
+      if @vagrant.nil?
+        return
+      end
+
+      unless build.env[:vagrant_disable_destroy]
+        listener.info "Build finished, destroying the Vagrant box"
         @vagrant.cli('destroy', '-f')
       end
     end

views/vagrant/package_publisher/config.erb

@@ -0,0 +1,10 @@
+<%
+f = taglib("/lib/form")
+f.block do
+    f.entry(:title => 'Name of .box file (optional)',
+            :field => 'boxname',
+            :description => 'Name to give the .box file packaged by Vagrant') do
+        f.textbox
+    end
+end
+%>