CODEWITHSUNDEEP
pythonpython-3.xflasktwilioflask-sockets
Kevin Cohen
Kevin Cohen

Reputation: 1341

Handling async streams in flask with twilio

I have a basic flask app to serve twilio calls. When a call is generated via twilio it goes to my /test http api.

In this api I'm generating a twiml conversation where the first thing that happens is a verb just saying "hello world". Then, concurrently I start a stream in the background. I'm using flask_sock for handling websocket connections in my flask app.

Here is my flask app route function that gets executed when the twilio call starts

@app.route('/test', methods=['POST'])
def test():
   response = VoiceResponse()
   connect = Connect()
   connect.stream(url=f'wss://{request.host}/stream')
   response.say("hello world")
   response.append(connect)
   response.pause(length=30)
   return str(response), 200, {'Content-Type': 'text/xml'}

Everything works when my stream is not async.

@sock.route('/stream')
def stream(ws):    
    do_something()

When I try to make my stream function async, like this:

@sock.route('/stream')
async def stream(ws):    
    await do_something()

I get RuntimeWarning: coroutine 'stream' was never awaited And my socket gets automatically terminated (ConnectionError)

How can I make this work with async?

For extra context: I'm running my flask app like this and then just running flask run

app = Flask(__name__)
sock = Sock(app)

... functions described above

if __name__ == '__main__':
    app.run(debug=True)

I cannot await the stream function because I'm not calling it, it's just a websocket entrypoint for twilio to initiate..

Upvotes: 0

Views: 395

Answers (1)

anthonyjdella
anthonyjdella

Reputation: 623

Hopefully this documentation helps, TwiML Voice: < Stream >.

Per the documentation,

The < Start > verb starts the audio < Stream > asynchronously and immediately continues with the next TwiML instruction. If there is no instruction, the call will be disconnected. In order to avoid this, provide a TwiML instruction to continue the call.

If you'd prefer a synchronous bi-directional stream, you should use the < Connect > verb.

So instead of connect, try start!

Upvotes: 0

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