Somehow the installation instructions for Docker never work for me and the website is surprisingly cagey about the manual process.
It works perfectly well if you just grab the relevant bits of that script and run them manually, but usually fails if you let it be a bit too magical.
To be fair, I probably have issues due to the mismatch of LSB release since I run Mint. Still though.
So here's the commands for Ubuntu:
$ apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys 58118E89F3A912897C070ADBF76221572C52609D $ echo deb https://apt.dockerproject.org/repo ubuntu-vivid main > /etc/apt/sources.list.d/docker.list $ apt-get update && apt-get install -y docker-engine