Seperate DB container for each service. Three main reasons: 1) if one service requires special configuration that affects the whole DB container, it won’t cross over to the other service which uses that DB container and potentially cause issues, 2) you can keep the version of one of the DB containers back if there is an incompatibility with a newer version of the DB and one of the services that rely on it, 3) you can rollback the dataset for the DB container in the event of a screwup or bad service (e.g. Lemmy) update without affecting other services. In general, I’d recommend only sharing a DB container if you have special DB tuning in place or if the services which use that DB container are interdependent.