add new GPG key detailed in Docker installation

Question

completely new to 'Docker', wondered what this means in installation instructions. https://docs.docker.com/engine/installation/linux/ubuntulinux/

4/ Add the new GPG key.
 sudo apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --   recv-keys 58118E89F3A912897C070ADBF76221572C52609D

Answer 1

This is part of the SecureApt (strong crypto to validate downloaded packages)

apt-key is a program that is used to manage a keyring of gpg keys for secure apt.
gpg is the tool used in secure apt to sign files and check their signatures

That works... if the key server is up (see issue 13555 , and " Key server times out while installing docker on Ubuntu 14.04 ")

The pool hkp://p80.pool.sks-keyservers.net is a subset of servers which are also available on port 80. It's more friendly to firewalls and companies.

For some reason, most docker documentations and tutorials are giving that p80 pool for installation, without further explanation.

The thing is, this is a small pool of servers and they fail very often in practice. (The fact that most tutorials are sending people to that small pool probably doesn't help either).