Minimal Alpine Linux Docker container with sshd exposed and rsync installed.
Mount your .ssh credentials (RSA public keys) at /root/.ssh/ in order to access the container via root ssh.
Optionally mount a custom sshd config at /etc/ssh/.
docker run -d -p 2222:22 -v ~/.ssh/id_rsa.pub:/root/ssh-config/authorized_keys:ro -v /mnt/data/:/data/ quay.io/elifarley/sshd