title: Why use Vagrant as post-processor with Packer while building virtualbox OVA
body: <p>I am new to Packer and I am building Virtualbox images with Packer. It works fine so far and I can build my VMs.</p>
  
  <p>However, I am wondering why people are using Vagrant as post processor to build the OVA as in the example below :</p>
  
  <pre><code>"post-processors": [
      {
        "type": "vagrant",
        "compression_level": "9",
        "output": "debian-{{user `debian_version`}}-amd64_{{.Provider}}.box",
        "only": ["virtualbox-iso"]
      }
  ],
  </code></pre>
  
  <p>For me, the virtualbox-iso builder already provides an OVA file, so why use Vagrant after this ?</p>
  
  <p>Thanks</p>