Based on: https://github.com/giampaolo/pyftpdlib/blob/master/demo/basic_ftpd.py
docker build . -t filantus/ftp
docker run --name=ftp -e FTP_USER=user -e FTP_PASS=qwerty -p 21:21 --rm -it filantus/ftp
docker run --name=ftp \
-e FTP_USER=user \
-e FTP_PASS=qwerty \
-e FTP_PORT=10021 \
-e PASV_PORTS=10022-10029 \
-p 10021-10029:10021-10029 \
--rm -it filantus/ftp
FTP_USER - required
FTP_PASS - required
FTP_ROOT - default: /var/ftp
FTP_PORT - default: 21
PASV_PORTS - default: 40000-65535
PASV_ADDRESS - default: None