Problem with message_queue redis database number

[hem4nt]

I have two flask_socketio apps running which use message_queue="redis://localhost:6379/2" and message_queue="redis://localhost:6379/1" respectively.
But it looks like I'm doing it wrong or it is not honouring the database numbers 2 and 1 but may be using 0 as default because when I broadcast some message from an external process, it gets broadcast from both the apps!

In the external processes I initialise the app like this:

   socketio = SocketIO()
   socketio.init_app(None, message_queue=f"redis://localhost:6379/{db_number}")

Can you please help?

[miguelgrinberg]

I'm not sure, because the URL that you provide is passed intact to the redis package. Any chance your db_number variable is zero or empty?

[hem4nt]

When I create the redis object I do it as below and it takes db number as a separate argument. So passing the URL intact is not enough? I remember it ignoring the db number in the URL when I had tried it earlier.

from redis import Redis
from app.app_config import config


def create_redis():
    redis = Redis(config['REDIS']['REDIS_HOSTNAME'],
                  db=config['REDIS']['REDIS_DB_NUM'])
    return redis

[miguelgrinberg]

@hem4nt I don't understand what is this code you are showing me. This package creates its own Redis connections from the URL that you pass, so what is the significance of your own method of creating Redis connections?

[hem4nt]

@miguelgrinberg, Sorry that code is from my app but not related to this package. I brought that here to point out that Redis() takes an argument db for db number. So I guess flask_socketio package must be extracting the db number from the message_queue arguement and pass separately as db to Redis() and passing the url alone intact may not cause Redis() to point to the correct db number.
I'm sure I'm passing correct url to socketio.init_app() and couldn't think of any other problem.

[miguelgrinberg]

No, Flask-SocketIO passes the URL to Redis. It is Redis that parses it to obtain the database number. See the Redis.from_url function.