Free version of mattermost doesn't provide any message/attachment retention settings so this simple script cleans up posts and attachments
Script can work on standalone or dockerized deployment, however in the case of docker you must run it on application container (otherwise it wont be able to delete the files from the system. It was tested with official mattermost docker deployment.
This script currently supports mattermost instances using both mysql or postgres database.
Just specify mysql or postgres on the DB_DRIVE variable.