There are a few limitations but it will work if you are using host networking --net host or have a direct/routed network between the Docker container and the client.

Virtual User

The FTP user has been set to uid 48 and gid 48.

Options

The following environment variables are accepted.

FTP_USER: Sets the default FTP user
FTP_PASSWORD: Plain text password, or
FTP_PASSWORD_HASH: Sets the password for the user specified above. This requires a hashed password such as the ones created with mkpasswd -m sha-512 which is in the whois debian package.
FTP_USER_*: Adds mutliple users. Value must be in the form of username:hash. Should not be used in conjunction with FTP_USER and FTP_PASSWORD(_HASH).
FTP_USERS_ROOT: sets local_root=/srv/$USER so each user is chrooted to their own directory instead of a shared one.

Usage Example

docker run --rm -it -p 21:21 -p 4559:4559 -p 4560:4560 -p 4561:4561 -p 4562:4562 -p 4563:4563 -p 4564:4564 -e FTP_USER=panubo -e FTP_PASSWORD=panubo docker.io/panubo/vsftpd

SSL Usage

SSL can be configured (non-SSL by default). Firstly the SSL certificate and key need to be added to the image, either using volumes or baking it into an image. Then specify the vsftpd_ssl.conf config file as the config vsftpd should use.

This example assumes the ssl cert and key are in the same file and are mounted into the container read-only.

docker run --rm -it \
-e FTP_USER=panubo -e FTP_PASSWORD_HASH='$6$XWpu...DwK1' \
-v `pwd`/server.pem:/etc/ssl/certs/vsftpd.crt:ro \
-v `pwd`/server.pem:/etc/ssl/private/vsftpd.key:ro \
docker.io/panubo/vsftpd vsftpd /etc/vsftpd_ssl.conf