Why cant I use wss endpoints on replit

Replit Help
1 
@app.websocket('/temperature/ws')
async def websocket_endpoint(websocket: WebSocket):
    await websocket.accept()
    while True:
        data = fetch_data_db()  # Fetch data from Cosmos Mongodb
        await websocket.send_json(data)
        await asyncio.sleep(1)  # Add a delay to prevent overwhelming the client

So, that is a very simple websocket endpoint that I want to use for my API. But for some reason, when I tried the endpoint in postman. I got this:

wss://arduino-temp-api.replit.app/temperature/ws

Error: Unexpected server response: 404
Handshake Details
Request URL: https://arduino-temp-api.replit.app/temperature/ws
Request Method: GET
Status Code: 404 Not Found
Request Headers
Sec-WebSocket-Version: 13
Sec-WebSocket-Key: hCoalH2sqvSzKvcW+M2Bww==
Connection: Upgrade
Upgrade: websocket
Sec-WebSocket-Extensions: permessage-deflate; client_max_window_bits
Host: arduino-temp-api.replit.app
Response Headers
Content-Length: 22
Content-Type: application/json
Date: Tue, 21 Nov 2023 12:45:14 GMT
Server: Google Frontend
Strict-Transport-Security: max-age=63072000; includeSubDomains
Traceparent: 00-9cc6e035935df382ad3f9cbc74c2286b-d2e977cd4596d871-01
X-Cloud-Trace-Context: 9cc6e035935df382ad3f9cbc74c2286b/15197810141057964145;o=1
Via: 1.1 google
Alt-Svc: h3=":443"; ma=2592000,h3-29=":443"; ma=2592000
Connection: close

Obviously, my primary domain uses https. So I understand that trying to establish a websocket connection to a https domain will not work (Obviously).

But this led me down into a rabbit hole, I have checked the domain settings, and yes. I could see that one can add subdomains. And yes, I am aware that I can link a domain. But that would mean that

A: I would have to get a domain elsewhere and link it, doing the DNS settings stuff etc or:

B: Create a wss domain using replit, but that leads us to our next problem

So I decided to create a new replit project with only my socket endpoints. I checked the deployment settings. And I couldn’t see anything that pointed towards creating a wss domain. (And now before you ask, one can not just simply add “wss://” when creating a primary domain. Because when creating a domain this is what the error message from replit says:
“Can only contain alphanumeric characters and hyphens” )

As you can see, I feel pretty lost here. I tried googling it, but this seems to be a very unique problem.
When googling I either encountered TicTacToe tutorials that aren’t helpful at all, or nothing at all. The least useful stuff I found this this guy:Custom domain websocket
Who literally just said: “solved using express” or whatever.

2

You can use WSS endpoints on Replit, using express and other similar packages will handle pretty much everything for you so that you literally can just add wss:// to the front. Here’s a template that I made that uses WebSockets, essentially all I do is:

const express = require("express");
const app = express();
const server = require("node:http").createServer(app);

const ws = new (require("ws").Server)({ noServer: true });

server.on("upgrade", function(req, socket, head) {
	ws.handleUpgrade(req, socket, head, function(client) {
		// `client` is your WebSocket which you can now use
	});
});

server.listen();

Alternatively, it is even easier using a library like Socket.IO:

const express = require("express");
const app = express();
const server = require("node:http").createServer(app);

const io = new (require("socket.io").Server)(server);
io.on("connection", function(socket) {
	// `socket` is your WebSocket which you can now use
});

server.listen();

These are both NodeJS examples, but it should be relatively similar in Python. There is also Socket.IO for Python.

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