A vagrantfile that sets up ruby for a development environment on Ubuntu.

Ruby dev vagrantfile.rb

# -*- mode: ruby -*-
# vi: set ft=ruby :
$script = <<SCRIPT
echo I am provisioning...
date > /etc/vagrat_provisioned_at
echo installing git...
sudo apt-get update
sudo apt-get install -y git-core
echo installing curl...
sudo apt-get install -y curl
echo installing library dependencies...
sudo apt-get install -y libxslt-dev 
sudo apt-get install -y libxml2-dev
sudo apt-get install -y libpq-dev
echo installing ruby 2.1 using brightbox ppa
sudo apt-get install -y python-software-properties
sudo apt-add-repository -y ppa:brightbox/ruby-ng 
sudp apt-get update
sudo apt-get install -y ruby2.1 
echo end of provisioning
SCRIPT

Vagrant.configure("2") do |config|
  # All Vagrant configuration is done here. The most common configuration
  # options are documented and commented below. For a complete reference,
  # please see the online documentation at vagrantup.com.

  # Every Vagrant virtual environment requires a box to build off of.
  config.vm.box = "precise32"
  # config.vm.hostname = "RubyonRails"
  config.vm.provision :shell, :inline => $script
  config.vm.network :forwarded_port, guest: 3000, host: 3001
end

Added ruby installation as shown in http://www.pinupgeek.com/Brightbox-Ruby-2.1-Ubuntu-Packages/. Don't see the need for rvm for vagrant development environments.