Engines

Five engines, each the official image, each one entry in a table. What differs is below; everything else — the container, the network, the data directory, attaching — is the same.

The first version listed is what a database created without naming one gets. Versions are pinned rather than open because a version cannot be changed afterwards — offering one is a promise to keep running it.

Postgres

The connection URL carries sslmode=disable: there is no TLS on the instance's network, and none over an exposed port either, and clients that default to requiring it need telling.

Backups are pg_dump in one transaction — the database as it was at a single moment — and restore with --clean --if-exists, so restoring over a database that already has tables replaces them.

MySQL and MariaDB

root is refused as the login: it already exists, the image gives it a random password Cubeship never stores, and Cubeship never connects as it. Yours is created beside it.

Backups are mysqldump / mariadb-dump with --single-transaction, which covers InnoDB tables. A MyISAM table is dumped as it was read rather than as it was when the dump began.

Redis

One login, default, and the password belongs to it — Redis's own rule. Naming another user is refused, not silently overwritten.

There is no named database, so the variables carry no _NAME. It is started with --appendonly yes, because otherwise Redis snapshots on its own schedule and a restart loses the last few minutes — free for a cache, and somebody's queue otherwise.

Redis is not backed up, on purpose. It is a cache and a queue on a box this size, and there is no good answer to what a nightly copy of one would be restored to. Its page offers no Backups tab rather than an empty one.

MongoDB

The connection string carries authSource=admin: the root user lives in the admin database whatever database the connection names, and without it every connection fails on credentials that are correct.

Backups are mongodump --archive, and they are each collection as it was read, not all of them at one moment — a consistent snapshot needs a replica set, which a single server is not. Restore is mongorestore --drop.

Two things every engine shares

The data is the mount point, never below it. Each image chowns its data directory to the unprivileged user it drops to, and a mount above that stays root-owned. Postgres 18 in particular moved its default below the volume, and left alone would keep its data in an anonymous volume nothing here names — in no backup, and orphaned the next time the container is replaced. Cubeship says where the data goes.

The password is delivered the way the image reads it. Through the environment for the SQL engines and Mongo; on the command line for Redis, whose image has no variable for it. Either way it is in the container's configuration, where docker inspect on the host reads it.