Well, Vagrant provides a hook for different provisioning frameworks. I believe that Puppet and Chef and officially supported. The project uses Chef, which is written in ruby and uses ruby-based cookbooks to do its work. So it is pretty unavoidable. Also, Vagrant is written in Ruby last I checked, so if you are using Vagrant you already have a Ruby dependency.

Sorry if I've misunderstood.

As an aside, I thought it would be cool to build a service like this, so it's great that somebody did it. However the name definitely has the wrong connotation.