Flask-CeleryExt

0.5.0 verified Fri May 01 auth: no python

Flask-CeleryExt provides a simple integration layer between Celery and Flask, offering a Flask extension for configuring Celery applications. Current version is 0.5.0 (requires Python >=3.6), with a maintenance-level release cadence.

pip install flask-celeryext

Common errors

error AttributeError: module 'flask_celeryext' has no attribute 'create_celery_app' ↓

cause Importing directly from 'flask_celeryext' without upgrading to a version that includes create_celery_app (added in 0.4.0).

fix

Upgrade to flask-celeryext>=0.4.0: pip install --upgrade flask-celeryext

error celery.exceptions.ImproperlyConfigured: No broker configured ↓

cause Forgetting to set 'CELERY_BROKER_URL' in Flask app config, or setting it with wrong key name.

fix

Ensure app.config['CELERY_BROKER_URL'] is set to a valid broker URL (e.g., 'redis://localhost:6379/0')

error RuntimeError: Working outside of application context ↓

cause Using Celery tasks outside of Flask application context without proper setup.

fix

Initialize Celery using FlaskCeleryExt(app) or use 'with app.app_context():' when executing tasks outside request context.

Warnings

gotcha Flask-CeleryExt expects Celery configuration keys like 'CELERY_BROKER_URL' (uppercase with CELERY_ prefix). Using lowercase or missing prefix will silently default to localhost. ↓

fix Set config keys with 'CELERY_' prefix, e.g., app.config['CELERY_BROKER_URL'] = '...'.

deprecated The 'BROKER_URL' configuration key (without CELERY_ prefix) is deprecated as of v0.4.2. Use 'CELERY_BROKER_URL' instead. ↓

fix Replace app.config['BROKER_URL'] with app.config['CELERY_BROKER_URL'].

gotcha Flask-CeleryExt does not automatically handle Flask application context for Celery tasks. You must use the @celery.task decorator within an application context or use the create_celery_app helper to avoid context issues. ↓

fix Use the provided 'create_celery_app' function or ensure tasks are defined after the extension is initialized with the app.

Imports

FlaskCeleryExt

from flask_celeryext import FlaskCeleryExt

Correct import path

create_celery_app
```
from flask_celeryext import create_celery_app
```
Helper function to create Celery app

Quickstart

Minimal Flask app with Celery task using Flask-CeleryExt.

from flask import Flask
from flask_celeryext import FlaskCeleryExt

app = Flask(__name__)
app.config['CELERY_BROKER_URL'] = 'redis://localhost:6379/0'
app.config['CELERY_RESULT_BACKEND'] = 'redis://localhost:6379/0'
ext = FlaskCeleryExt(app)
celery = ext.celery

@celery.task
def add(x, y):
    return x + y

if __name__ == '__main__':
    app.run()