Tips & Troubleshooting#
When running Flask-APScheduler on a wsgi process only 1 worker should be enabled. APScheduler 3.0 will only work with a single worker process. Jobstores cannot be shared among multiple schedulers.
See APScheduler’s documentation for further help.
Take a look at the Examples to see how it works.
Flask-Appscheduler will start a scheduler when running with an environment variable of FLASK_DEBUG=true and using flask’s werkzeug server OR when running with FLASK_DEBUG=false and a production server (gunicorn etc). If you have server details coded directly into the app you can use a pattern like this to help with development.
from flask.helpers import get_debug_flag if get_debug_flag(): app.run() else: .... wsgi server run forever
Mixing Persistent Jobstores with Tasks from Config#
When using a persistent jobstore, do not register jobs from a configuration file. They should be registered by decorators (see example), or by using the add_job method.
Mixing Persistent Jobstores with Tasks in __init__.py#
Tasks registered via decorator or the add_job method should not be loaded in your app/__init__.py if you are using a persistent job store. If they must be loaded upon app creation, a workaround would be as follows:
# app/__init__.py scheduler = APScheduler() db = SQLAlchemy() <other stuff> def create_app(config_class=Config): app = Flask(__name__) app.config.from_object(config_class) db.init_app(app) scheduler.init_app(app) scheduler.start() <other stuff> @app.before_first_request def load_tasks(): from app import tasks return app # app/tasks.py @scheduler.task('cron', id='do_renewals', hour=9, minute=5) def scheduled_function(): # your scheduled task code here
Your task will then be registered the first time that someone makes any request to the Flask app.
Trying to Load Tasks Outside Module-Level Import#
If your task was loading correctly with the default memory jobstore, but does not load correctly from a persistent jobstore, this is because functions to be loaded as jobs must be available as module-level imports when used with persistent jobstores. They cannot be nested within other functions or classes.
So this function could be added using the add_job method:
# app/tasks.py def your_function(): # your scheduled task code here # other_module.py scheduler.add_job(<details here>)
You could accomplish the same by importing modules that contain decorated functions (un-nested, at the module level):
# app/tasks.py @scheduler.task('cron', id='do_renewals', hour=9, minute=5) def scheduled_function(): # your scheduled task code here # other_module.py from app import tasks
But this would not work:
# some_module.py def do_stuff(): # do some stuff before registering a task # then attempt to register a task, which will fail due to nesting @scheduler.task('cron', id='do_renewals', hour=9, minute=5) def scheduled_function(): # your scheduled task code here