Because no one actually implements a standard

fix_ovf.rb

#!/usr/bin/env ruby -w
# fix_ovf: convert virtualbox ovf documents to work with vmware
# Usage: fix_ovf < vbox.ovf > vmware.ovf

require 'nokogiri'

class OVFDocument < Nokogiri::XML::Document
  XMLNS = {
    'rasd' => "http://schemas.dmtf.org/wbem/wscim/1/cim-schema/2/CIM_ResourceAllocationSettingData",
    'vssd' => "http://schemas.dmtf.org/wbem/wscim/1/cim-schema/2/CIM_VirtualSystemSettingData",
    'base' => "http://schemas.dmtf.org/ovf/envelope/1",
    'ovf' => "http://schemas.dmtf.org/ovf/envelope/1",
    'xsi' => "http://www.w3.org/2001/XMLSchema-instance",
    'vbox' => "http://www.virtualbox.org/ovf/machine"
  }

  # Insert a new file with the given attributes
  # :href :: filename of the file
  # :id   :: identifier inside the OVF
  def add_file(attrs)
    file = Nokogiri::XML::Node.new 'File', self
    file['ovf:href'] = attrs[:href] if attrs[:href]
    if attrs[:id]
      file['ovf:id'] = attrs[:id]
    else
      n = filecount + 1
      file['ovf:id'] = "file#{n}"
    end
    at('//ovf:References').add_child file
  end

  def filecount
    search('//ovf:References/ovf:File').count
  end

  def add_virtual_system_type(type)
    at('//vssd:VirtualSystemType').content += " #{type}"
  end

  def find_item_by_resource_type(type)
    at("//rasd:ResourceType[text()=\"#{type}\"]/..")
  end

  def add_vmware_support
    %w(vmx-04 vmx-06 vmx-07).each {|t| add_virtual_system_type t}

    find_item_by_resource_type(20).tap do |i|
     i.at('./rasd:Caption', XMLNS).content = 'scsiController0'
     i.at('./rasd:Description', XMLNS).content = 'SCSI Controller'
     i.at('./rasd:ElementName', XMLNS).content = 'scsiController0'
     i.at('./rasd:ResourceSubType', XMLNS).content = 'lsilogic'
     i.at('./rasd:ResourceType', XMLNS).content = '6'
    end
  end

  def search(path, ns = {})
    super path, XMLNS.merge(ns)
  end
end


@doc = OVFDocument.parse(ARGF)
@doc.add_file(:href => 'Vagrantfile')
@doc.add_vmware_support
@doc.write_to STDOUT