This Docker container implements a vsftpd server, with the following features:

• Centos 7 base image.
• vsftpd 3.0
• Virtual users
• Passive mode
• Logging to a file or STDOUT.

You can download the image with the following command:

docker pull zhangguanzhang/vsftpd

This image uses environment variables to allow the configuration of some parameteres at run time:

• Variable name: PASV_ADDRESS
• Default value: Docker host IP.
• Accepted values: Any IPv4 address.
• Description: If you don't specify an IP address to be used in passive mode, the routed IP address of the Docker host will be used. Bear in mind that this could be a local address.

• Variable name: PASV_MIN_PORT
• Default value: 21100.
• Accepted values: Any valid port number.
• Description: This will be used as the lower bound of the passive mode port range. Remember to publish your ports with docker -p parameter.

• Variable name: PASV_MAX_PORT
• Default value: 21110.
• Accepted values: Any valid port number.
• Description: This will be used as the upper bound of the passive mode port range. It will take longer to start a container with a high number of published ports.

• Variable name: LOG_STDOUT
• Default value: null.
• Accepted values: Any string to enable, empty string or not defined to disable.
• Description: Output vsftpd log through STDOUT, so that it can be accessed through the container logs.

The image exposes ports 20 and 21. Also, exports two volumes: /home/vsftpd, which contains users home directories, and /var/log/vsftpd, used to store logs.

When sharing a homes directory between the host and the container (/home/vsftpd) the owner user id and group id should be 14 and 80 respectively. This correspond ftp user and ftp group on the container, but may match something else on the host.

1. Create a temporary container for testing purposes and the default config_file:

$  docker run --rm -v $PWD/virtual_users.txt:/etc/vsftpd/virtual_users.txt zhangguanzhang/vsftpd

$  docker run --rm zhangguanzhang/vsftpd grep -Pv '^$|^#' /etc/vsftpd/vsftpd.conf
background=NO
anonymous_enable=NO
local_enable=YES
guest_enable=YES
virtual_use_local_privs=YES
write_enable=YES
pam_service_name=vsftpd_virtual
user_sub_token=$USER
local_root=/home/vsftpd/$USER
chroot_local_user=YES
allow_writeable_chroot=YES
hide_ids=YES
pasv_addr_resolve=NO
xferlog_enable=YES
xferlog_file=/var/log/vsftpd/vsftpd.log
port_enable=YES
connect_from_port_20=YES
ftp_data_port=20
seccomp_sandbox=NO
pasv_enable=YES
pasv_address=127.0.0.1
pasv_max_port=21110
pasv_min_port=21100

2. Create a container in active mode using your own user account, with a binded data directory:

$ cat virtual_users.txt 
myuser
mypass
$ docker run -d -p 21:21 -v /my/data/directory:/home/vsftpd -v $PWD/virtual_users.txt:/etc/vsftpd/virtual_users.txt --name vsftpd zhangguanzhang/vsftpd
# see logs for credentials:
docker logs vsftpd

3. Create a production container with a custom user account, binding a data directory and enabling both active and passive mode:

$ cat virtual_users.txt 
myuser
mypass
$ docker run -d -v /my/data/directory:/home/vsftpd \
-p 20-21:20-21 -p 21100-21110:21100-21110 \
-e PASV_ADDRESS=127.0.0.1 \
-v $PWD/virtual_users.txt:/etc/vsftpd/virtual_users.txt \
-v $PWD/vsftpd.conf:/etc/vsftpd/vsftpd.conf \
--name vsftpd --restart=always zhangguanzhang/vsftpd

4. Manually add a new FTP user to an existing container:

docker exec -i -t vsftpd bash
mkdir /home/vsftpd/myuser
echo -e "myuser\nmypass" >> /etc/vsftpd/virtual_users.txt
/usr/bin/db_load -T -t hash -f /etc/vsftpd/virtual_users.txt /etc/vsftpd/virtual_users.db
exit
docker restart vsftpd