What is not covered here is the “how” part.
Currently, according to app-cache, I have docker-engine installed:
docker-engine/ubuntu-trusty,now 17.05.0~ce-0~ubuntu-trusty amd64 [installed]
and I get the warning
WARNING: Docker version 17.05.0-ce deprecated, recommend upgrade to 17.06.2 or newer.
However the Get Docker CE for Ubuntu instructions start with “Uninstall old versions docker or docker-engine” before installing docker-ce.
Needless to say, anything that starts with “uninstall stuff” makes me more than a little nervous as to how much of my site it plans on deleting, and how safe it is to go ahead and uninstall docker-engine, and then install docker-ce, and expect my site to be there and working when I finish. How safe is this process? If I have a site working with docker-engine, and I follow the Get Docker CE for Ubuntu instructions, uninstall docker-engine, install docker-ce via the “Install using the repository” instructions, am I likely to actually have a working site at the end of it?