# package configure.zcml
(...)

  <!-- -*- extra stuff goes here -*- -->

  <include package="plone.app.registry" />
  <include package="collective.lead" />

  <i18n:registerTranslations directory="locales" />

  <utility
    provides="collective.lead.interfaces.IDatabase"
    factory=".dbsettings.CalculatorDatabase"
    name="test.calc.db"
    />

# dbsettings.py

from zope.component import getUtility
from plone.registry.interfaces import IRegistry

(...)

class CalculatorDatabase(Database):
    """
    The database for our calculator
    """

    @property
    def _url(self):
        registry = getUtility(IRegistry)
        settings = registry.forInterface(IDatabaseSettings)
        return URL(
            drivername=settings.drivername,
            username=settings.username,
            password=settings.password,
            host=settings.hostname,
            port=settings.port,
            database=settings.database,
        )