Flask WebSockets Invalid session...

I modified my Python Flask server to use socket.io-client and am seeing errors logged after deploy. The service remains running but the server is not responding to requests properly... Any help is much appreciated!

Invalid session 8nIFLl8Lm_WsCd_2AAAA (further occurrences of this error will be logged with level INFO)
[2023-05-15 13:02:53 +0000] [10] [ERROR] Socket error processing request.
Traceback (most recent call last):
File "/opt/venv/lib/python3.8/site-packages/gunicorn/workers/sync.py", line 134, in handle
self.handle_request(listener, req, client, addr)
File "/opt/venv/lib/python3.8/site-packages/gunicorn/workers/sync.py", line 190, in handle_request
util.reraise(*sys.exc_info())
File "/opt/venv/lib/python3.8/site-packages/gunicorn/util.py", line 625, in reraise
raise value
File "/opt/venv/lib/python3.8/site-packages/gunicorn/workers/sync.py", line 181, in handle_request
resp.write(item)
File "/opt/venv/lib/python3.8/site-packages/gunicorn/http/wsgi.py", line 326, in write
self.send_headers()
File "/opt/venv/lib/python3.8/site-packages/gunicorn/http/wsgi.py", line 322, in send_headers
util.write(self.sock, util.to_bytestring(header_str, "latin-1"))
File "/opt/venv/lib/python3.8/site-packages/gunicorn/util.py", line 286, in write
sock.sendall(data)
OSError: [Errno 9] Bad file descriptor

a686cf21-bbfd-4ddb-9e0c-5c11cd434e88

the problem suggests that you are sending data to a socket that doesnt exist

and it cant know the file descriptor because the socket file doesnt exist

websockets module works for me thats the only thing i can tell

also use the PORT environment variable if you didnt set it in the service settings to something else cause if you didnt, it automatically makes ssl work for you without anything and it your subdomain will work

Did you have to install any package like eventlet?

Also do I need to set up the PORT environment variable? Sorry I did not get the last part..

want the subdomain?

no but it should still work, websockets works

if you want the subdomain, dont set it in service env variables

instead

import os

and set port to os.environ['PORT']

it will automatically forward it to

and on 443 port

for websockets you need to use

wss:// tho

(wss:// for with ssl

ws:// without)

Sorry I am still learning about this and can't follow...
What do you mean by want the subdomain?

subdomain is the part of the url

you know

subdomain.domain.com

or something

thats what you type in a browser

subdomain.subdomain.domain.com

the main domain is the last one

you need to pay for domains

but for subdomains you can just create a directoryon the machine that is hosting the web app(depends on your software)

Since I am hosting the service on Railway, I am assuming my subdomain is
flask-production-bcb7.up.railway.app

Is that correct?

where you found that

but it seems correct

In the service setting

change it to what you want

yes

but for custom domain you need to use your own so dont click on that button

if you dont have a domain bought

Oh I don't want to use custom domain yet

and do I need to set this URL anywhere?

read the websockets documentation if you want to use it

no

only when you connect

I have this in my frontend React to create the socket
const newSocket = socketIOClient(process.env.REACT_APP_SERVER_URL, {
query: { token }
});
setSocket(newSocket);

and the env variable is just the https:// subdomain

I was able to talk to my server fine until I added websocket

@ImLunaHey can probably help you better if he has time

i am not so much into web stuff, i never used react or web frameworks, dont ask me

she*

i checked your twitch and you have a male voice, are you transgender or smth? am i wrong?

doesnt matter what my voice sounds like... there are loads of cis/trans men/women who have deep/high voices. if someone corrects their pronouns just leave it at that.

ok sorry, i didnt know

gonna have to provide more info than that. got a link to a repo or a code sample?

The errors states you're using a closed socket.

Thanks for helping, to both of you!

Let me post the repo here

So in this repo, I have a React app and Flask server

okay, and what did you do before the error occurred? Started the app? went to a specific endpoint?

After start_chat in ln75

in main.py

not seeing anything that's sticking out.

does this happen when you first start the app or when you connect?

If I redeploy the service and do not execute this code in App.js in React, seems like things are fine
// Initialize socket connection here
const newSocket = socketIOClient(process.env.REACT_APP_SERVER_URL, {
query: { token }
});
setSocket(newSocket);

Once I create the Socket, server starts to log the error message

did you mean to use socketio and not regular websockets?

theyre not the same thing

Hmmm. I am totally new to this...

yeah theyre not the same thing, that's likely the issue here.

You cannot just use a socketio client to connect to a standard websocket server.

But I think both the React and Flask server are socket.io?

Could you help me check on the main.py script

hmm, okay you are using flask_socketio for the server so that might not be the issue.

personally id use actual websockets instead as socketio adds a whole layer of unknowns

sorry i couldnt be of more help

ok. Let me try switch
So websocket might be more reliable?

yes, it is a lot better

yeah, the issue itself is the socket is not connected and you're trying to send it data.

it handles pings by default

and stuff

its very good and nice

I see. I would try that!

and very easy to set up

Thank you both so much!

this will help

it has asyncio, threading, sans io support