def create_app():

    app = Flask(__name__)

    _default_secret_key = base64.b64encode(os.urandom(32)).decode('utf-8')

    app.config['SECRET_KEY'] = os.environ.get('SECRET_KEY',

                                              _default_secret_key)

    if not hasattr(app.config, 'from_json'):

        def from_json(file, silent=True):

            try:

                with open(file, encoding='utf-8') as json_file:

                    obj = json.load(json_file)

            except IOError:

                if silent:

                    return False

                raise

            for key in obj:

                if key.isupper():

                    app.config[key] = obj[key]

            return True

        app.config.from_json = from_json

    app.config.from_json(config_file, silent=True)

    app.config.setdefault('BOOTSTRAP_SERVE_LOCAL', True)

    bootstrap.init_app(app)

    @app.after_request

    def add_headers(response):

        response.headers.setdefault('Access-Control-Allow-Origin', '*')

        response.headers.setdefault('Cache-Control', 'no-cache')

        return response

    from .views import root_views

    app.register_blueprint(root_views)

    from .state import state_views

    app.register_blueprint(state_views, url_prefix='/state')

    from .sensors import sensors_views

    app.register_blueprint(sensors_views, url_prefix='/sensors')