Building an OpenStack Cluster in VirtualBox

I had quite a time trying to get VirtualBox to work with OpenStack, and still haven't fully figured it out.  I can't ping the outside world, nor can I ping between the instances yet.  I'm hoping this article I just found will help.

One key point is, you have to create host only connections via Settings > Network for each OpenStack instance you create.  These host only connections provide an internal network between your host and the virtual machine instances.  Here's an example, from the link above:

VirtualBox OpenStack Network Diagram