Here is a quick way to setup VirtualBox using Vagrant with Heroku-like box on Mac.
Install VirtualBox from https://www.virtualbox.org/wiki/Downloads
Install Vagrant from http://downloads.vagrantup.com/
Create Vagrantfile for Heroku-like box (based on https://github.com/ejholmes/vagrant-heroku) that looks something like:
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Beside telling Vagrant to use Heroku-like box from https://github.com/ejholmes/vagrant-heroku it also sets up shared dir between host and VM machine. It will mount Vagrantfile dir (.) to /vagrant in VM.
vagrant up will setup the VM and start it up.
Now you can use
vagrant ssh to login to VM.
Vagrant Heroku-like box comes with Postgresql, but if you want you can easily setup sqlite:
Bonus tip: when you are working on multiple projects sometimes you can forget which VMs are running. You can list all running VMs using: