Django 3 and Daphne deploy

[nunesvictor]

Hi,

I'm trying to implement a simple socket emit with Django 3 and Daphne, but for some reason the event emited isn't never captured by the client. Here is my code

asgi.py

import os
import socketio

from django.core.asgi import get_asgi_application

os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'eleicoes.settings')

sio = socketio.AsyncServer(async_mode='asgi', cors_allowed_origins='*')
application = socketio.ASGIApp(sio, get_asgi_application())

views.py

from eleicoes.asgi import sio

# other code

print('emit vote event', sio)
sio.emit('user', UserSerializer(instance=request.user).data)

# other code

It simples doesn't work. I think I followed the documentation in this matter but I can't find anything with this specific setup (django 3 and daphne)

[miguelgrinberg]

@nunesvictor it would be useful if you enable Socket.IO logs in the server and the client and we can look at those to see where is this emit getting lost. For the server, add logger=True and engineio_logger=True arguments when you create your AsyncServer object. For the JS client see https://socket.io/docs/logging-and-debugging/.

[nunesvictor]

Thank you for your quick response. I think we found the problem, but I'm still struggling with the solution. I had to change the verbosity of daphne logs too, but it told me that:

web_1      | 2020-01-16 11:33:00,002 WARNING  Executing <Task pending name='Task-12' coro=<ASGI3Middleware.asgi() running at /usr/local/lib/python3.8/site-packages/daphne/cli.py:30> wait_for=<Future pending cb=[_chain_future.<locals>._call_check_cancel() at /usr/local/lib/python3.8/asyncio/futures.py:357, <TaskWakeupMethWrapper object at 0x7f566d57c880>()] created at /usr/local/lib/python3.8/asyncio/base_events.py:418> created at /usr/local/lib/python3.8/site-packages/daphne/server.py:205> took 0.106 seconds
web_1      | 2020-01-16 11:33:00,314 WARNING  ./api/views.py:206: builtins.RuntimeWarning: coroutine 'AsyncServer.emit' was never awaited

I think emit has to be called with await, but I can't get into it because my api call (simple Django REST Framework view call) is a synchronous one. How can I encapsulate that async call inside a sync one?

Sorry for the throubles and thank you!

[miguelgrinberg]

@nunesvictor oh, you are mixing asyncio and standard apps, I think that's a recipe for trouble. Do you have a good reason to do that? Why not use the Server class instead of AsyncServer, which is fully compatible with WSGI and thus Django?

[nunesvictor]

Actually I don't think I have a good reason. I just couldn't make uWSGI work for that. It always fails on firsts attempts to connect, something like Error: xhr poll error and then connects after a few attempts.

Also, the event emited on my view doesn't reach the client I and can't put my finger on why.

[nunesvictor]

My alternative setting to run with runserver and/or uWSGI is this one:

wsgi.py

import os
import socketio

from django.core.wsgi import get_wsgi_application

os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'eleicoes.settings')

sio = socketio.Server(
    cors_allowed_origins='*',
    engineio_logger=True,
    async_mode='gevent',
    logger=True,
)

application = socketio.WSGIApp(sio, get_wsgi_application())

and in my views.py I try to emit the signal with

sio.emit('vote', UserSerializer(instance=request.user).data)

and I run uWSGI with this ini file

[uwsgi]
base = /app
app = wsgi

processes = 10
max-requests = 4000
limit-as = 1024
buffer-size= 32768

pythonpath = %(base)/src
http-socket = 0.0.0.0:8000
chmod-socket = 666
vaccum = true
module = eleicoes.%(app):application

static-map = /static=/app/src/staticfiles
static-expires = /* 7776000
offload-threads = %k

gevent = 10

Note than it's not working with runserver and uWSGI ether

[miguelgrinberg]

Socket.IO is an asynchronous server. If you are going to use uWSGI you have to use it along with gevent. There are a few options that are based on WSGI besides that, see the documentation on deployment to find what works best for you.

[nunesvictor]

I honestly don't know how to thank you. Apparently the problem was I had added the wrong async_mode on socketio.Server. I'll put the correct configuration down here to whoever this may help in the future.

myapp.wsgi

import os
import socketio

from django.core.wsgi import get_wsgi_application

os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'myapp.settings')

sio = socketio.Server(
    async_mode='gevent_uwsgi',
    # implement allowed origins
    # cors_allowed_origins='*',
    # uncomment to enable logging
    # engineio_logger=True,
    # logger=True,
)

application = socketio.WSGIApp(sio, get_wsgi_application())

uWSGI command line
uwsgi --http :8000 --gevent 1000 --http-websockets --master --module myapp.wsgi:application

[miguelgrinberg]

I suggest you remove cors_allowed_origins='*'. This is basically allowing anybody to connect to your server, and can open the door to CSRF attacks. My recommendation is that you explicitly name the allowed origins instead.

[nunesvictor]

Will do