➜  ~ sudo apt-get update
Hit:1 http://security.ubuntu.com/ubuntu xenial-security InRelease
Hit:2 http://us.archive.ubuntu.com/ubuntu xenial InRelease
Ign:3 https://apt.dockerproject.org/repo ubuntu-xenial InRelease
Hit:4 https://apt.dockerproject.org/repo ubuntu-xenial Release
Hit:5 http://us.archive.ubuntu.com/ubuntu xenial-updates InRelease
Hit:6 http://us.archive.ubuntu.com/ubuntu xenial-backports InRelease
Reading package lists... Done
➜  ~ apt-cache policy docker-engine
N: Unable to locate package docker-engine