This image is a basic Ubuntu image with ssh installed and a scripted startup to allow creation of user accounts with corresponding SSH keys.
Python is installed on this image for utility.
Mount authorized_keys files in /opt/user_keys named as the desired user to be created (any extension will be stripped).
Persistent storage can be mounted at /home and /etc/ssh/keys if you wish the user home directories and SSH host keys to be maintained between container runs.