Happily this is largely the same as for Ubuntu 16.04 Xenial Xerus. The official steps are available here.

sudo apt-get update
sudo apt-get install apt-transport-https ca-certificates -y
sudo apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80
    --recv-keys 58118E89F3A912897C070ADBF76221572C52609D
sudo echo deb https://apt.dockerproject.org/repo ubuntu-xenial main >>
    /etc/apt/sources.list.d/docker.list
sudo apt-get update
sudo apt-get purge lxc-docker
sudo apt-get install linux-image-extra-$(uname -r) -y
sudo apt-get install docker-engine cgroup-lite apparmor -y
sudo usermod -a -G docker $USER
sudo service docker start

Happy Dockering!