How to enable logging in the docker container

How would I go about enabling logging in the docker container? The docs state:

You can customize the default settings of Kanboard by adding a file config.php at the project root or in the data folder.

So I tried adding a config.php in the data volume mounted at /var/www/app/data containing the following:

define('DEBUG', true);
define('LOG_DRIVER', 'file');
define('LOG_FILE', __DIR__.DIRECTORY_SEPARATOR.'data'.DIRECTORY_SEPARATOR.'debug.log');

But that only results in those define statements being shown on top of my dashboard and no logging enabled.

Well I figured it out. I have to also add <?php to the beginning of the file to make it work.