Instead of `curl $url | apt-get add -` use the ubuntu keyserver and a full fingerprint to retreive the key. This makes the distribution of the GPG key more secure an less likely to change even if 3rd party gains access to the packages repository. Docker-DCO-1.0-Signed-off-by: Jonas Pfenniger <zimbatm@zimbatm.com> (github: zimbatm) Upstream-commit: 13ebc68636f922e799d71792748934b8883d2f1f Component: engine