Metabase
Use the embedded H2 database (this db contains users, saved queries etc). The database is a mounted as a file from the local filesystem into the container.
To take backups, backup /root/metabase.db
Installation
If there are any existing backups, place them in /root/metabase.db.
Then add the Nginx conf
sudo mv metabase.nginx.conf /root/nginx/conf.d
and reload the nginx service.
Update
Take a DB backup (just for safety), then restart the service (it'll pull the latest image).
sudo systemctl stop metabase
sudo cp -R /root/metabase.db metabase.db-backup-`date '+%s'`
sudo systemctl start metabase