 
Automatically restart SSH sessions and tunnels
autossh is a program to start a copy of ssh and monitor it, restarting it as necessary should it die or stop passing traffic. More informations on the official autossh website.
This image is based on alpine.
The default ENTRYPOINT is /entrypoint.sh and the default CMD is --help.
/entrypoint.sh installs all the files under /install/ to /root/.ssh/, and executes autossh.
Take a look at the autossh README to see all the available parameters.