In the README.md, it is suggested to simply link an existing MySQL or PostgreSQL instance via --link command, however, when the container is stopped and started, it falls back to installation wizard and we have to enter the database credentials once again interactively.

This is not helpful in cases where automated container upgrades are set up (e.g. with watchtower). There should be environment variable support like most other web service containers provide accepting database host, database user, database password and database name environment variables.