This post will explain how to use -e DISPLAY flag on Mac OS X, so that you can get a GUI to your container. Furthermore it covers the basic steps of installing the boot2Docker VM, that runs the Docker engine, on OS X.

##How to install Docker on OS X ###Step by step instruction

On OS X there is the convenient possibility to install all necessary tools via Homebrew:

brew install caskroom/cask/cask-brew
brew install virtualbox
brew install docker
brew install boot2docker

Now you’re ready to fire up the boot2docker VM with the docker engine:

boot2docker init
boot2docker up
%Display the environment variables for the Docker client:  
boot2docker shellinit

To test your installation, you can now start your first Docker container by typing:
docker run -t -i ubuntu:14.04 /bin/bash
This starts an interactive session and gives you a shell in the container.

##How to get a GUI on OS X On a Linux host you can do pretty basic X11 forwarding. A guide on how to do it, can be found here or here. On OS X there is no comparable way of achieving this, but there is a crude way to get a GUI for your Docker container. A discussion about the topic and the explanations of the smart people who discovered that, can be found here.

You need socat, which is a command line based utility that establishes two bidirectional byte streams and transfers data between them, and XQuartz - Apples version of the X server.

brew install socat   
brew cask install xquartz

So start XQuartz:

open -a XQuartz

Expose local xquartz socket via socat on a TCP port

socat TCP-LISTEN:6000,reuseaddr,fork UNIX-CLIENT:\"$DISPLAY\"

Now all you have to do is pass the display to the Container:

% in another window   
docker run -it -e DISPLAY= batmat/docker-eclipse

Docker container running Eclipse Luna

Note: the IP saved in DISPLAY is the one of your virtual box host.