Warning message is always triggered: already exists and will be overriden

I am using docker-compose with the container and the mentioned warning message is always triggered as the symbolic link already exists:

Line 83 in 170a023

if [ -f "/etc/fail2ban/action.d/${action}" ]; then

So the check should be if the file exists and is NOT already the right target?

This warning is legit if you're overriding a core action. You can change the action filename in your data folder if this is not done on purpose.