Using Docker with Cockpit CMS

I am trying to install cockpit CMS using Docker VM (dockerfile) and using mongodb.

installation is working fine, altough, I think I am doing something wrong or cockpit is structured that way, my point :

when creating a collection, a file is created inside docker container in the storage folder and data is stored in mongodb
if I rebuild docker or restart, the storage folder is cleaned up and I loose all my collections.

how can I store storage folder outside docker container, Since I am using mongodb, isn't it supposed to store everything on mongodb ?

am I missing something on the configuration side ? any toughts, help appreciated

thank you

agentejo / cockpit-docker