create a systemd drop-in directory for the docker service:
mkdir /etc/systemd/system/docker.service.d
Now create a file called /etc/systemd/system/docker.service.d/http-proxy.conf that adds the HTTP_PROXY environment variable:
[Service] Environment="HTTP_PROXY=http://proxy.example.com:80/"
Flush changes:
sudo systemctl daemon-reload
Verify that the configuration has been loaded:
sudo systemctl show --property Environment docker Environment=HTTP_PROXY=http://proxy.example.com:80/
Restart Docker:
sudo systemctl restart docker