How to install Docker on Ubuntu 16.04

How To Install and Use Docker on Ubuntu 16.04 (very well explained + provides interesting details + it works)

Installing Wharfer on one of the AD machines

> sudo vim /etc/docker/daemon.json
{
    "userns-remap": "<remap_user | default >"
}
# Currently the remap user needs to be created per machine
# It needs to be added to /etc/subuid, /etc/subgid manually because these aren't
# automatically updated with our user management (they are on standard Ubuntu).

# If the name "default" is used docker creates a "dockremap" user.
# In this case the /etc/subuid, /etc/subgid files need to look like the following so that
# the processes in the container appear as "nobody" on the host
> sudo vim /etc/subuid
… append ..
dockremap:65534:65536
> sudo vim /etc/subgid
… append …
dockremap:65534:65536

# If more security than provided by wharfer is needed (e.g. lots of students)
# also install https://github.com/ad-freiburg/docker-no-trivial-root
# Note however that its restrictions then also apply to non-wharfer docker 
# use while wharfer alone does not impact other docker use

Install wharfer following the instructions at the Build/Download and Setup sections here

Docker Troubleshooting

"docker: Got permission denied while trying to connect" or "ERROR: Couldn't connect to Docker daemon" (2018-01-19)

WARNING: This is defacto equivalent to root access

We're currently working on two solutions that combined should in the future be relatively safe. These are wharfer and docker-no-trivial-root

Add user to group docker and switch to that group:

sudo usermod -aG docker <username>
# Logout
# Login
newgrp docker