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.
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 OpenStack documentation:
|VirtualBox OpenStack Network Diagram|