Docker - Command line - Thumbnails ownership

Hi,

I'm using the latest docker version.

It seems that thumbnails generated by /var/www/html/cron/make_thumbs.php are root-owned which keeps me from deleting folders on my smb share from my windows workstation. They're generated through a cron script calling

docker exec filerun php /var/www/html/cron/make_thumbs.php

Would it be possible to configure thumbnail ownership either through customizable config.php or through a way to run script as other UID than root within the docker image (found this https://stackoverflow.com/questions/6913403/running-command-line-application-from-php-as-specific-user) ?

Thanks a lot - really loving the new version by the way