lack of security best practices in docker container (chmod 777)

There are files and directories with chmod 777 in the container. chmod 777 or chmod 666 should never be done in production because that means that files can be replaced by any user or application vulnurability in the system! Not even /tmp is chmod 777 for good reasons.

Some files are chmod -R 777 from the entrypoint.sh script. A fact that should be removed as well.

Files in /var/www/html are writeable by the www-data user. Programs on your system should not be able to be modified by the user they are executed with. If an attacker is able to replace a running binaries through vulnerabilities those open permissions can be used to do privilege escalation.