I download a lot of linux images, by far the quickest way is via torrent. Recently discovered a nice implementation of rtorrent in a Docker image, via docktorrent, simple enough to run:
docker run -itd --restart=always --dns 220.127.116.11 -p 31405:80 -p 45566:45566 -p 9527:9527/udp -v /path/to/mount/rtorrent:/rtorrent -e UPLOAD_RATE=1024 kfei/docktorrent
31405 is the public facing port for the web interface, make sure that you forward both
45566 as it’ll need those to run.