Extended rtorrent + ruTorrent Docker image from https://github.com/linuxserver/docker-rutorrent with added sort script.
Once a torrent finishes downloading, sort.py is called which moves the torrent's data to a new directory based on its tracker, according to a yaml config file, and resumes seeding. To customize the sorting, mount your own sort-config.yaml into /config/rtorrent/sort-config.yaml.