We run a Flask site under IIS on Windows, and for out-of-process tasks we use Celery. Celery has given us some problems under Windows, but for now we are satisfied running version 3.1.12, using RabbitMQ/AMQP as a back-end, which works under Windows.
The new version of Celery (4) has dropped support for Windows, so I'm looking for a viable alternative.
RQ seems a very nice task queue, but it also does not support Windows (bottom of the page)
I have seen some more, seemingly less popular task queues like:
But it's unclear if these support Windows and Flask. I'm wondering if anyone has experience running a Python task queue under Windows which works. Maybe one of the ones I mentioned, or an alternative.
It's not an option for us to run a Linux machine, because we have no experience administering Linux, and we have a lot of legacy stuff running that requires Windows.
I run Flask with Huey on Windows without any issues, admittedly only for development and testing. For production I use Flask/Huey on Linux servers. Both with the Redis back-end, Flask 0.12 and Huey 1.2.0 .
I use the factory pattern to create a specialised "cut down" version of a Flask app for specific use by Huey tasks. This version doesn't load blueprints or configure Flask-Admin as these aren't required in the Huey tasks.
Example code of __init__.py in app folder. App is a class extending from Flask:
def create_app(settings_override=None):
app = App('app')
if settings_override:
app.config.from_object(settings_override)
else:
app.config.from_object(os.environ['APP_SETTINGS'])
from .ext import configure_extensions
configure_extensions(app, admin, load_modules=True)
# REST
import rest.api_v1
app.register_blueprint(api_v1_bp, url_prefix='/api/v1')
# ... and more suff
def create_huey_app():
app = App('huey app')
app.config.from_object(os.environ['APP_SETTINGS'])
from .ext import configure_extensions
configure_extensions(app, admin=None, load_modules=False)
return app
The idea of configure_extensions is taken from Quokka CMS. Examine its app __init__.py and its extensions module to see how this is implemented. Note also how this project too creates a specific app (create_celery_app) for use with the Celery task queue.
Example of tasks.py. Note the use of with app.app_context(): to create the Flask context. Now my functions have access to the extensions such as Flask-Mail, Flask-SqlAlchemy (db, models) etc.
@huey.task()
def generate_transaction_documents_and_email(transaction_id):
app = create_huey_app()
with app.app_context():
reports.generate_transaction_documents_and_email(transaction_id)
@huey.task()
def send_email(subject, recipients, text_body, html_body, attachments=[], cc=[]):
app = create_huey_app()
with app.app_context():
emails.send_email(subject, recipients, text_body, html_body, attachments, cc)
@huey.periodic_task(crontab(minute='30'))
def synchronize_mailing_list():
app = create_huey_app()
if app.config['CREATESEND_SYNCHRONIZE']:
_list_name = app.config['CREATESEND_LIST']
with app.app_context():
sync_delete_ar_subscribers(_list_name)
sync_add_ar_subscribers(_list_name)