… so I don’t forget.
“docker pull” will not use the HTTP_PROXY variable. Why? Because “docker” is just the cli program which tells the daemon what to do. And the daemon probably does not know about the variable if just set in the terminal.
So, what to do to make docker use it described pretty well here: https://docs.docker.com/articles/systemd/#http-proxy
Next thing: Don’t forget to go “systemctl daemon-reload”, because otherwise this will not be effective, even with “systemctl restart docker”.