MongoDB authentication to different DB than used no longer works in spring boot 3.1

[bpfoster]

After upgrading from Spring Boot 3.0 to 3.1 today, MongoDB authentication via the autoconfiguration is broken.

If you configure both a database to use, and a separate database to authenticate against, the authentication database is ignored, and authentication is attempted against the to-be-used database.

In versions past, and the intended behavior is, that specifying the authentication database allows authenticating as the user to that DB and then switching over to the configured database for normal operations.

Perhaps the PropertiesMongoConnectionDetails should append the authSource option to the connection string if authenticationDatabse is present?

[ps-tunnelsoft]

@scottfrederick can you have a look at a similar issue of spring-boot-docker-compose MongoDB autoconfiguration?

The StringBuilder in class MongoDockerComposeConnectionDetailsFactory is also missing the authSource option. But I am not sure, where to take this value from.

MONGO_INITDB_ROOT_USERNAME and MONGO_INITDB_ROOT_PASSWORD are used to create a root user by default in admin database and not MONGO_INITDB_DATABASE.

[scottfrederick]

@ps-tunnelsoft From reading the documentation for the official MongoDB image, I think you're right.

MONGO_INITDB_ROOT_USERNAME, MONGO_INITDB_ROOT_PASSWORD
These variables, used in conjunction, create a new user and set that user's password. This user is created in the admin authentication database

We might need to set the authentication database to the value admin if the username and password environment variables are configured. Can you create a new issue so we can investigate further?