I find this the easiest way to install Discourse on OS X for local development purpose. The idea is this: you install Ubuntu as a VM and setup Discourse on top of that.
Setup Vagrant is as easy as double click the installer and a couple of next click. I have a license for Parallels 9 so I use Parallels as default provider. You can use VMWare if you own one or VirtualBox for free if you don’t feel like paying.
I use puphpet’s Ubuntu 14.04 x64 as base box but literally, anything Ubuntu 14.04 would work. Ubuntu 14.04 is recommended version by Discourse.
You can use PuPHPet online GUI configurator to create a configuration of your own.
vagrant plugin install vagrant-parallels mkdir discourse-local cd discourse-local vagrant init puphpet/ubuntu1404-x64 vagrant up --provider=parallels vagrant ssh
Install Discourse with Docker
Follow this tutorial on Discourse Meta to setup Discourse on your Vagrant box.
Discourse should be up and running on your Vagrant box’s IP address after this.