That doesn't work for databases unless you stop the container. You'll likely end up with a corrupt backup.

?

Any decent RDBMS can be backup live without issues. You only need to stop for restore (well without going with complex tricks)

Then stop the container.

A self hosted app can have a few minutes of downtime at 3am while the backup script runs.

Streaming replication to a read-only DB off-site.

Shut that one down and back it up from time to time.

Then copy that to a third site with rsync/etc