Let ULLD help you generate a configuration file.
ULLD defaults to SQLite for it's ease of installation, but permits Postgres for performance and portability.
For security reasons, ULLD will write your connection string to a pair of environment variables, POSTGRES_URL and POSTGRES_URL_POOLING. You can change your database to any other Postgres instance by changing these variables in the future.
POSTGRES_URL
POSTGRES_URL_POOLING
Either a connection URI or a database name and port number are required to use Postgres.