Misleading message at runtime for previsously supported Docker engine

[piroux]

Today, as part of regular deployments, which include installing Docker-CE on Ubuntu Trusty 14.04, it took me some time to understand why they were failing.
After finding the one-script-fits-all, I finally understood why:

$ sudo sh get-docker.sh                                                                                                                                                                                                                                       
# Executing docker install script, commit: 40b1b76
+ sh -c apt-get update -qq >/dev/null
+ sh -c apt-get install -y -qq apt-transport-https ca-certificates curl >/dev/null
+ sh -c curl -fsSL "https://download.docker.com/linux/ubuntu/gpg" | apt-key add -qq - >/dev/null
+ sh -c echo "deb [arch=amd64] https://download.docker.com/linux/ubuntu trusty edge" > /etc/apt/sources.list.d/docker.list
+ sh -c apt-get update -qq >/dev/null
+ sh -c apt-get install -y -qq --no-install-recommends docker-ce >/dev/null
+ sh -c docker version
Client:
 Version:           18.06.3-ce
 API version:       1.38
 Go version:        go1.10.3
 Git commit:        d7080c1
 Built:             Wed Feb 20 02:27:13 2019
 OS/Arch:           linux/amd64
 Experimental:      false

Server:
 Engine:
  Version:          18.06.3-ce
  API version:      1.38 (minimum version 1.12)
  Go version:       go1.10.3
  Git commit:       d7080c1
  Built:            Wed Feb 20 02:25:38 2019
  OS/Arch:          linux/amd64
  Experimental:     false
If you would like to use Docker as a non-root user, you should now consider
adding your user to the "docker" group with something like:

  sudo usermod -aG docker your-user

Remember that you will have to log out and back in for this to take effect!

WARNING: Adding a user to the "docker" group will grant the ability to run
         containers which can be used to obtain root privileges on the
         docker host.
         Refer to https://docs.docker.com/engine/security/security/#docker-daemon-attack-surface
         for more information.

** DOCKER ENGINE - ENTERPRISE **

Test drive additional security features by activating Docker Engine - Enterprise.

  * Leverage FIPS 140-2 validated encryption
  * Run only trusted images with digital signature enforcement

** Learn more at https://dockr.ly/engine1 **

ACTIVATE your own engine to Docker Engine - Enterprise using:

  sudo docker engine activate

I understand that it is time to sunset Ubuntu 14.04 support for Docker, but it would be great if we could be offered a more understandable message, after installing it unattended and trying to execute any image, than that:

$ sudo usermod -a -G docker ubuntu                                                                                                                                                                                                                            
$ docker run hello-world                                                                                                                                                                                                                                      
docker: Error response from daemon: OCI runtime create failed: container_linux.go:348: starting container process caused "process_linux.go:301: running exec setns process for init caused \"exit status 23\"": unknown.
ERRO[0000] error waiting for container: context canceled

Note that I decided to not post this message as a Docker-CE Issue because the installed package is not one of this kind anymore.

[seemethere]

Most likely related to docker/for-linux#591

Going to close this issue since it's not directly tied to the installation script, but feel free to join the discussion in the issue linked above.