def get_database_uri() -> str:
    """Get database uri for whole system.

    - Get database uri:
        - environmental variables
        - default uri that uses sqlite at local file system
    - Process with database uri
        - add a fixed time_zone utc
        - ...


    Returns:
        str: database uri with utc timezone
    """
    uri = ''
    if 'SQLALCHEMY_DATABASE_URI' in os.environ:
        uri = os.getenv('SQLALCHEMY_DATABASE_URI')
    else:
        uri = 'sqlite:///{}?check_same_thread=False'.format(
            os.path.join(BASE_DIR, 'app.db'))
    return _turn_db_timezone_to_utc(uri)
Get database uri for whole system.

    - Get database uri:
        - environmental variables
        - default uri that uses sqlite at local file system
    - Process with database uri
        - add a fixed time_zone utc
        - ...


    Returns:
        str: database uri with utc timezone
    
web_console_v2/api/fedlearner_webconsole/db.py