auto start script in debian

I want to have an auto start script for my project. I use docker and want to try a script that starts if the container start.

I tried to run update-rc and i dont have any problems but the symbolic links dont get generated. I checked it in the file explorer and with my script:

mkdir /var/www/$(date +%Y%m%d_%H%M%S)

But nothing happend.
This is in my dockerfile:

COPY /etc/init.d/
RUN chmod +x /etc/init.d/
RUN chmod 755 /etc/init.d/
RUN update-rc.d defaults 10

I dont get any error messages. Thats my problem 🙂

Source: StackOverflow