sql_from_env.py

def engine_from_environ(prefix, settings, application_name=None):
    """Setup an SQLAlchemy engine with overrides from environment.

    Maps KEYS_LIKE_THIS to keys.like.this"""
    env_prefix = prefix.replace('.', '_').upper()
    for env in os.environ:
        if env.startswith(env_prefix):
            key = env.replace('_', '.').lower()
            settings[key] = os.environ[env]
    if application_name is not None:
        sqlalchemy_url = prefix + 'url'
        settings[sqlalchemy_url] = add_application_name(
            settings[sqlalchemy_url],
            application_name,
        )