Streamlit Deployment with Websocket Server

Deployment
1

Hi,
I am trying to deploy a streamlit app and a websocket server on Heroku and I have been able to successfully do the same. However, the error occurs once I have made the deployment. When I open the Heroku app and check the logs from both the dynos (I have 2 dynos: web and worker). The worker dyno runs the websocket server. According to the logs the web application is unable to send any requests to the websocket server. I have also confirmed that the address I am connecting to in the app is the correct one. Please let me know where I am going wrong given this is the first deployment I am making.

Here is the code for my websocket_server.py

import os
import asyncio
import websockets
import signal

CONNECTED_CLIENTS = set()

async def handler(websocket, path):
    CONNECTED_CLIENTS.add(websocket)
    print(f"Client connected: {websocket.remote_address}")
    try:
        async for message in websocket:
            print(f"Received message: {message}")
            for client in CONNECTED_CLIENTS:
                if client != websocket and client.open:
                    await client.send(message)
    finally:
        CONNECTED_CLIENTS.remove(websocket)
        print(f"Client disconnected: {websocket.remote_address}")

async def main():
    loop = asyncio.get_running_loop()
    stop = loop.create_future()
    loop.add_signal_handler(signal.SIGTERM, stop.set_result, None)

    port = int(os.environ.get("PORT", "8001"))
    async with websockets.serve(handler, "", port):
        print(f"WebSocket server started on :{port}")
        await stop

if __name__ == "__main__":
    asyncio.run(main())

Here is the code for my streamlit app:

import streamlit as st
import asyncio
import websockets

async def send_command(command):
    try:
        async with websockets.connect("wss://hololens-sense-9bd80b459134.herokuapp.com/") as websocket:
            await websocket.send(command)
            print(f"Sent command : {command}")
    except Exception as e:
        print(f"Error sending command: {e}")

def send_command_async(command):
    loop = asyncio.new_event_loop()
    asyncio.set_event_loop(loop)
    loop.run_until_complete(send_command(command))

st.title("Remote Control for HoloLens")

col1, col2 = st.columns([3, 1])

with st.container():
    with col1:
        if st.button("Increase Distance"):
            send_command_async("increase_distance")

        if st.button("Decrease Distance"):
            send_command_async("decrease_distance")

        if st.button("Toggle Left"):
            send_command_async("toggle_left")       

        st.subheader("Increase Quad Size")

        left_slider = st.slider("Select aspect ratio of Quad", min_value=0.0, max_value=1.0, value=0.5, step=0.01)
        st.write(f"Quad Aspect Ratio: {left_slider}")        

        st.subheader("Change Filter Mode")
        if st.button("Filter Point"):
            send_command_async("filter_point")
        
        if st.button("Filter Bilinear"):
            send_command_async("filter_bilinear")
        
        if st.button("Filter Trilinear"):
            send_command_async("filter_trilinear")
        
        if st.button("Toggle Grayscale"):
            send_command_async("toggle_grayscale")
    

    with col2:
        st.write("")

        if st.button("⬆️ Up"):
            send_command_async("move_up")
        
        col2_left, col2_right = st.columns(2)

        with col2_left:
            if st.button("⬅️ Left"):
                send_command_async("move_left")
        
        with col2_right:
            if st.button("➡️ Right"):
                send_command_async("move_right")
        
        st.write("")  # Add some space below the buttons
        if st.button("⬇️ Down"):
            send_command_async("move_down")
        
        st.subheader("Move Quad to Position")
        if st.button("Bottom Left"):
            send_command_async("bottom_left")

        if st.button("Bottom Right"):
            send_command_async("bottom_right")

        if st.button("Top Left"):
            send_command_async("top_left")

        if st.button("Top Right"):
            send_command_async("top_right")

if st.session_state.get('previous_slider_value') != left_slider:
    st.session_state['previous_slider_value'] = left_slider
    send_command_async(f"slider_value:{left_slider}")

Here is the setup.sh file and Procfile:

mkdir -p ~/.streamlit/

echo "\
[general]\n\
email = \"your-email@domain.com\"\n\
" > ~/.streamlit/credentials.toml

echo "\
[server]\n\
headless = true\n\
port = $PORT\n\
enableCORS = false\n\
\n\
" > ~/.streamlit/config.toml

web: sh setup.sh && streamlit run app.py --server.port=$PORT
worker: python websocket_server.py