PSA: Docker on Ubuntu

$ sudo apt-get install docker
$ which docker
$ docker
The program 'docker' is currently not installed. You can install it by typing:
apt-get install docker
$ apt-get install docker
Reading package lists... Done
Building dependency tree
Reading state information... Done
docker is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 13 not upgraded.

Oh, you wanted to run a docker container? The docker package in Ubuntu is some window manager dock thingy. The docker binary that runs containers comes from the system package.

$ sudo apt-get install
$ which docker

Also, if it can’t connect to its socket:

FATA[0000] Post http:///var/run/docker.sock/v1.18/containers/create: dial
unix /var/run/docker.sock: permission denied. Are you trying to connect to a
TLS-enabled daemon without TLS?

you need to make sure you’re in the right group:

sudo usermod -aG docker <username>; newgrp docker

(thanks, stackoverflow!)