I've spent the last couple of days struggling to install the Ironwood release of Open edX in an Ubuntu 16.04 Virtualbox. After struggling with various issues, I came across this post in the General Open edX Google Group:

https://groups.google.com/forum/?utm_medium=email&utm_source=footer#!msg/edx-code/cgMseEEKGAg/wgvld6EkAwAJ

The following instructions worked for me to finally install a stable copy of the platform:

sudo apt-get update -y
sudo apt-get upgrade -y
sudo reboot
sudo su 
export OPENEDX_RELEASE=open-release/ironwood.master

I then created the config.yml file in the current directory:

# The host names of LMS and Studio. Don't include the "https://" part:

EDXAPP_LMS_BASE: "example.com"
EDXAPP_CMS_BASE: "studio.example.com"
wget https://raw.githubusercontent.com/edx/configuration/$OPENEDX_RELEASE/util/install/ansible-bootstrap.sh -O - | sudo bash
wget https://raw.githubusercontent.com/edx/configuration/$OPENEDX_RELEASE/util/install/generate-passwords.sh -O - | bash
wget https://raw.githubusercontent.com/edx/configuration/$OPENEDX_RELEASE/util/install/native.sh -O - | bash

The install took almost an hour on a small Virtualbox but it did complete. The step that I believe made all the difference was running as a superuser:

sudo su