app.py

from flask import Flask, render_template
from flask_socketio import SocketIO
from flask_socketio import emit
from flask_cors import CORS

app = Flask(__name__)

socketio = SocketIO(app, cors_allowed_origins="*")

CORS(app)


@app.route('/')
def index():
    return render_template('index.html')


@socketio.on('message')
def handle_message(data):
    emit('message', data, broadcast=True)


if __name__ == '__main__':
    socketio.run(app, host='0.0.0.0', debug=True, allow_unsafe_werkzeug=True)