Docker Ubuntu raring 13.04 image creation

ubuntu_image.sh

sudo debootstrap raring raring > /dev/null
cd raring

# prevent init scripts from running during install/update
echo $'#!/bin/sh\nexit 101' | sudo tee usr/sbin/policy-rc.d > /dev/null

# see https://github.com/dotcloud/docker/issues/446#issuecomment-16953173
sudo chmod +x usr/sbin/policy-rc.d

# shrink the image
sudo chroot . apt-get clean

# forces dpkg not to call sync() after package extraction and speeds up install
echo 'force-unsafe-io' | sudo tee etc/dpkg/dpkg.cfg.d/02apt-speedup > /dev/null

#  we don't need an apt cache in a container
echo 'Acquire::http {No-Cache=True;};' | sudo tee etc/apt/apt.conf.d/no-cache > /dev/null

sudo tar -c . | sudo docker import - ubuntu-raring