Environment:
- Ubuntu 16.04.6
- conda 4.12.0
- Apache/2.4.18 (Ubuntu)
- python==3.8.1
- Django==4.0.3
- channels==3.0.5
- asgi-redis==1.4.3
- asgiref==3.4.1
- daphne==3.0.2
I am attempting to create a websocket service that only relays messages from redis to an authenticated user. Users do not communicate with each other, therefore I don't need Channel layers and my understanding is that Channel layers are an entirely optional part of Channels.
I'm simply trying to broadcast messages specific to a user that has been authenticated through custom middleware. I have custom auth middleware that takes an incoming session id and returns the authenticated user dictionary along with a user_id. I'm also attaching this user_id to the scope.
I have elected to route all traffic through daphne via Apache2 using ProxyPass on port 8033. This is preferred since I'm using a single domain for this service.
However, I'm really struggling to maintain a connection to the websocket server, particularly if I refresh the browser. It will work on the first request, and fail after with the following message in journalctl:
Application instance <Task pending name='Task-22' coro=<ProtocolTypeRouter.__call__() running at /root/miniconda2/lib/python3.8/site-packages/channels/routing.py:71> wait_for=<Future pending cb=[<TaskWakeupMethWrapper object at 0x7f658c03f670>()]>> for connection <WebSocketProtocol client=['127.0.0.1', 46010] path=b'/ws/userupdates/'> took too long to shut down and was killed.
After spending hours on the github for channels, and trying many of the suggestions (particularly found on https://github.com/django/channels/issues/1119), I'm still at a loss. The version of the code below is the best working version so far that at least establishes an initial connection, sends back the connection payload {"success": true, "user_id": XXXXXX, "message": "Connected"} and relays all redis messages successfully. But, if I refresh the browser, or close and reopen, it fails to establish a connection and posts the above journalctl message until I restart apache and daphne.
My hunch is that I'm not properly disconnecting the consumer or I'm missing proper use of async await. Any thoughts?
Relevant apache config
RewriteEngine On
RewriteCond %{HTTP:Connection} Upgrade [NC]
RewriteCond %{HTTP:Upgrade} websocket [NC]
RewriteRule /(.*) ws://127.0.0.1:8033/$1 [P,L]
<Location />
ProxyPass http://127.0.0.1:8033/
ProxyPassReverse /
</Location>
app/settings.py
[...]
ASGI_APPLICATION = 'app.asgi.application'
ASGI_THREADS = 1000
CHANNEL_LAYERS = {}
[...]
app/asgi.py
import os
from django.core.asgi import get_asgi_application
from django.urls import path
from channels.routing import ProtocolTypeRouter, URLRouter
from channels.security.websocket import AllowedHostsOriginValidator
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'app.settings')
import websockets.routing
from user.models import UserAuthMiddleware
application = ProtocolTypeRouter({
'http': get_asgi_application(),
"websocket": AllowedHostsOriginValidator(
UserAuthMiddleware(
URLRouter(websockets.routing.websocket_urlpatterns)
)
),
})
user/models.py::UserAuthMiddleWare
Pulls user_id from custom authentication layer and attaches user_id to scope.
class UserAuthMiddleware(CookieMiddleware):
def __init__(self, app):
self.app = app
async def __call__(self, scope, receive, send):
# Check this actually has headers. They're a required scope key for HTTP and WS.
if "headers" not in scope:
raise UserSessionError(
"UserAuthMiddleware was passed a scope that did not have a headers key "
+ "(make sure it is only passed HTTP or WebSocket connections)"
)
# Go through headers to find the cookie one
for name, value in scope.get("headers", []):
if name == b"cookie":
cookies = parse_cookie(value.decode("latin1"))
break
else:
# No cookie header found - add an empty default.
cookies = {}
# now gather user data from session
try:
req = HttpRequest()
req.GET = QueryDict(query_string=scope.get("query_string"))
setattr(req, 'COOKIES', cookies)
setattr(req, 'headers', scope.get("headers")),
session = UserSession(req)
scope['user_id'] = session.get_user_id()
except UserSessionError as e:
raise e
return await self.app(scope, receive, send)
websockets/routing.py
from django.urls import re_path
from . import consumers
websocket_urlpatterns = [
re_path(r'ws/userupdates/', consumers.UserUpdatesConsumer.as_asgi())
]
websockets/consumers.py::UserUpdatesConsumer
from channels.generic.websocket import JsonWebsocketConsumer
import json, redis
class UserUpdatesConsumer(JsonWebsocketConsumer):
def connect(self):
self.accept()
self.redis = redis.Redis(host='127.0.0.1', port=6379, db=0, decode_responses=True)
self.p = self.redis.pubsub()
if 'user_id' not in self.scope:
self.send_json({
'success': False,
'message': 'No user_id present'
})
self.close()
else:
self.send_json({
'success': True,
'user_id': self.scope['user_id'],
'message': 'Connected'
})
self.p.psubscribe(f"dip_alerts")
self.p.psubscribe(f"userupdates_{self.scope['user_id']}*")
for message in self.p.listen():
if message.get('type') == 'psubscribe' and message.get('data') in [1,2]:
continue
if message.get('channel') == "dip_alerts":
self.send_json({
"key": "dip_alerts",
"event": "dip_alert",
"data": json.loads(message.get('data'))
})
else:
self.send(message.get('data'))
