Bug Fix: AttributeError: 'Flask' object has no attribute 'before_first_request'.

1. Problem

The backend is broken. The backend container stopped and exited.

• The backend is broken, the frontend is unable to fetch data from the backend.

• The backend docker container is down.

2. Analysis

• The backend docker container log shows that something is wrong with the flask decorator.

• The @app.before_first_request decorator ensures that the init_rollbar() function is executed before the first request to the application.

  • Suitable for one-off initialization tasks in Flask

  

  Python is misleading here. @app.before_first_request is correct if ever, because it is for one-off task that has to execute prior to any request.

3. Solution

• The decorator before_first_request is depricated after Flask 2.2.

  • Use app.app_context() instead.

  • When indent the whole def init_rollbar() function into the with statement.

app.py

with app.app_context():
  def init_rollbar():
      """init rollbar module"""
      rollbar.init(
          # access token
          'YOUR_ACCESS_TOKEN'
          # environment name
          'production',
          # server root directory, makes tracebacks prettier
          root=os.path.dirname(os.path.realpath(__file__)),
          # flask already sets up logging
          allow_logging_basic_config=False)

      # send exceptions from `app` to rollbar, using flask's signal system.
      got_request_exception.connect(rollbar.contrib.flask.report_exception, app)

4. Result

• The Flask server is up and running again (the backend container is running!)

• The rollbar endpoint /rollbar/test is working.