The bundle has a
database_url configuration value that you can specify in your
app, either by hardcoding it, or by referencing an environment variable.
For this create
config/packages/dbp_relay_formalize.yaml in the app with the following
dbp_relay_formalize: database_url: 'mysql://db:secret@mariadb:3306/db?serverVersion=mariadb-10.3.30' # database_url: %env(FORMALIZE_DATABASE_URL)%
If you were using the DBP API Server Template as template for your Symfony application, then the configuration file should have already been generated for you.
For more info on bundle configuration see https://symfony.com/doc/current/bundles/configuration.html.