Flask-Melodramatiq 1.0

Flask-Melodramatiq is a Flask extension that adds support for the Dramatiq task processing library.

Dramatiq is a great library, and Flask-Melodramatiq tries hard not to force you to change the way you interact with it. Flask-Melodramatiq defines thin wrappers around the broker types available in Dramatiq, so that all the power of Dramatiq’s API remains available to you.

For example:

import dramatiq
from flask import Flask
from flask_melodramatiq import RabbitmqBroker

app = Flask(__name__)
broker = RabbitmqBroker(app)
dramatiq.set_broker(broker)

@dramatiq.actor
def task():
    print('Snakes appreciate good theatrical preformace.')

or, if you prefer the Flask application factory pattern:

import dramatiq
from flask import Flask
from flask_melodramatiq import RabbitmqBroker

broker = RabbitmqBroker()
dramatiq.set_broker(broker)

@dramatiq.actor
def task():
    print('Snakes appreciate good theatrical preformace.')

def create_app():
    app = Flask(__name__)
    broker.init_app(app)
    return app

In those examples, the broker instance that we created (we call it a “lazy broker”) is a genuine Dramatiq broker, and can be used anywhere where a “native” broker can be used. (It has dramatiq.brokers.rabbitmq.RabbitmqBroker as a superclass!) Lazy brokers are thin wrappers which add several important features:

1. They honor the settings in the Flask application configuration.

2. init_app can be called on them before or after the actors have been defined.

3. The Flask application context is correctly set during the execution of the tasks.

4. They add few convenience methods. (The Broker.actor decorator for example.)

from flask_melodramatiq import RabbitmqBroker

broker = RabbitmqBroker(
    url='amqp://mybroker:5672', confirm_delivery=True)

DRAMATIQ_BROKER_URL = 'amqp://mybroker:5672'
DRAMATIQ_BROKER_CONFIRM_DELIVERY = True

from flask_melodramatiq import Broker

broker = Broker()  # Broker's type is not specified here.

DRAMATIQ_BROKER_CLASS = 'StubBroker'

$ dramatiq wsgi:broker

from myapp import create_app, broker

app = create_app()

$ pip install Flask-Melodramatiq