Pass a POST request from Flask to a Celery task

Question

I have a long csv file upload task in Flask, and since it's long, I'd like to let Celery process it in the background, but how do I pass this request from the Flask route to a Celery task?

To build the route I followed the Flask documentation: https://flask.palletsprojects.com/en/2.0.x/patterns/fileuploads/

To configure Celery with Flask, I followed this tutorial by Miguel: https://blog.miguelgrinberg.com/post/celery-and-the-flask-application-factory-pattern

Based on the upload_file() route from the documentation, it would only have one task call to a Celery task:

@app.route('/', methods=['GET', 'POST'])
def upload_file():
    task = upload_file_task.delay(...)
    return jsonify({'task_id': task.id}), 202

And now the upload_file_task() function does everything the upload_file() route would do

Answer 1

Your code generally looks correct. That said, making sure celery runs correctly in production may be additional steps. You may also want to consider using the apply_async function instead of delay since that gives you some finer grained control over the queue and countdown parameters.