Socket.io + nodejs = Error during WebSocket handshake: Unexpected response code: 500 - node.js

Question

I've been working on chat functionality for my website hosted on Azure app service. I'm using the socket on port 443 as app service won't allow any other port than 80 and 443.
Socket functionality works fine on localhost but this error shows up when I deploy:
websocket.js:122 WebSocket connection to 'wss://mydomain/socket.io/?EIO=3&transport=websocket' failed: Error during WebSocket handshake: Unexpected response code: 500
this is I'm connecting on client-side:
const socket = io.connect("https://mydomain:443", {transports: ['websocket'], secure: true, port: '443'});
This is my server.js file
const express = require("express");
const mongoose = require("mongoose");
const bodyParser = require("body-parser");
const passport = require("passport");
const users = require("./routes/api/users");
const base = require("./routes/api/base");
const leads = require("./routes/api/leads");
const requests = require("./routes/api/requests");
const offApp = require("./routes/api/offApp");
const chat = require("./routes/api/chat");
const chatSocket = require("./routes/socket/chat");
const path = require("path"); // on top
const app = express();
const cors = require('cors')
const https = require('https');
const fs = require('fs');
/**
* App.
*/
const privateKey = fs.readFileSync('private.key').toString();
const certificate = fs.readFileSync('certificate.crt').toString();
const ca = fs.readFileSync('ca_bundle.crt').toString();
const server = https.createServer({key:privateKey,cert:certificate,ca:ca }, app);
const client = require('socket.io').listen(server);
app.use(function(req, res, next) {
res.header("Access-Control-Allow-Origin", "*"); // update to match the domain you will make the request from
res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
next();
});
client.origins('*:*');
client.set('transports', ['websocket']);
server.listen(443);
// Bodyparser middleware
app.use(
bodyParser.urlencoded({
extended: false
})
);
app.use(bodyParser.json());
// DB Config
const db = require("./config/keys").mongoURI;
// Connect to MongoDB
mongoose
.connect(
db,
{ useNewUrlParser: true }, (err, db) => {
if (err) {
throw err;
}
console.log('MongoDB connected');
chatSocket(db, client);
});
// Passport middleware
app.use(passport.initialize());
// Passport config
require("./config/passport")(passport);
// Routes
app.use("/api/users", users);
app.use("/api/base", base);
app.use("/api/leads", leads);
app.use("/api/requests", requests);
app.use("/api/offapp", offApp);
app.use("/api/chat", chat);
const port = process.env.PORT || 5000;
app.use(express.static("client/build")); // change this if your dir structure is different
app.get("*", (req, res) => {
res.sendFile(path.resolve(__dirname, "client", "build", "index.html"));
});
app.listen(port, () => console.log(`Server up and running on port ${port} !`));
I haven't found any error in logs

Answer 1

I was able to solve this problem by using the default port. (Not the best solution but for Azure App service I couldn't find any other solution)
For the client-side I am connecting to socket like this.
const socket = io.connect("https://example.com", {transports: ['websocket'], secure: true});
And this is how my server-side looks like.
const express = require("express");
const mongoose = require("mongoose");
const bodyParser = require("body-parser");
const passport = require("passport");
const users = require("./routes/api/users");
const base = require("./routes/api/base");
const leads = require("./routes/api/leads");
const requests = require("./routes/api/requests");
const offApp = require("./routes/api/offApp");
const chat = require("./routes/api/chat");
const chatSocket = require("./routes/socket/chat");
const path = require("path"); // on top
const app = express();
const cors = require('cors')
const https = require('https');
const fs = require('fs');
/**
* App.
*/
var privateKey = fs.readFileSync('private.key').toString();
var certificate = fs.readFileSync('certificate.crt').toString();
var ca = fs.readFileSync('ca_bundle.crt').toString();
// var server = https.createServer({key:privateKey,cert:certificate,ca:ca }, app);
var server = require('http').createServer(app);
var client = require('socket.io').listen(server);
app.use(function(req, res, next) {
res.header("Access-Control-Allow-Origin", "*"); // update to match the domain you will make the request from
res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
next();
});
client.origins('*:*');
client.set('transports', ['websocket']);
// Bodyparser middleware
app.use(
bodyParser.urlencoded({
extended: false
})
);
app.use(bodyParser.json());
// DB Config
const db = require("./config/keys").mongoURI;
// Connect to MongoDB
mongoose
.connect(
db,
{ useNewUrlParser: true }, (err, db) => {
if (err) {
throw err;
}
console.log('MongoDB connected');
chatSocket(db, client);
});
// Passport middleware
app.use(passport.initialize());
// Passport config
require("./config/passport")(passport);
// Routes
app.use("/api/users", users);
app.use("/api/base", base);
app.use("/api/leads", leads);
app.use("/api/requests", requests);
app.use("/api/offapp", offApp);
app.use("/api/chat", chat);
const port = process.env.PORT || 5000;
app.use(express.static("client/build"));
app.get("*", (req, res) => {
res.sendFile(path.resolve(__dirname, "client", "build", "index.html"));
});
server.listen(port);