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WebRTC python server: STUN/TURN servers for your python app

WebRTC python server: STUN/TURN servers for your python app

Ali Asgher's photo
Ali Asgher
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6 min read

Table of contents

Python is a versatile and accessible programming language that is known for its clear syntax and readability

This makes it a good choice for building webrtc applications

We can build a WebRTC server in python by using libraries such as aiortc

aortic library

  • Pure python Implementation:

    • The aiortc library is a pure python implementation of WebRTC and ORTC.

    • This means that you do not need to depend on any third party library or any other dependencies

  • Built on asyncio :

    • The aiortc is built on top of python's own asynciolibrary for async connections.

    • Thus allowing you to handle multiple concurrent connections easily

  • Media and data channels:

    • The library provides support for Video, audio as well as data channels, thus enabling a wide range of real time communication features.

  • Ease of Integration:

    • aiortc can be easily integrated with other python libraries such as aiohttp for web server as well as other third party libraries such as socket.io for real time event handling

  • Extensive documentation and examples:

    • the library aiortc comes with extensive documentation and different examples that can help you get started quickly

Setting Up a WebRTC Server in Python

Pre-requisites

  1. Python 3.x Installed:

    1. Make sure that you have the Python 3.x installed on your computer or server. You can check the python version like so 
python3 --version

  1. Basic Knowledge of async programming:

    1. You need basic knowledge of how asynchronous programming works.

    2. We are going to use the async library in this article which is important for simultaneous connections and data streams

Installing necessary libraries

using pip to install aiortc and other dependencies

aiortc is a pure python implementation of webrtcand ORTC. It uses python language async features to handle the real time communication

Install the libraries using pip like so

pip install aiortc aiohttp

  • aiorrtc provides the core WebRTC functionality

  • aiohttp is an asynchronous HTTP client/server framework, we are going to use this framework for signalling

Developing the server

Setting up signalling with WebSockets

  1. Setting up signalling with WebSockets

WebRTC needs a signalling mechanism in order to establish a connection.

WebRTC does this by exchanging SDP or session descriptions and ICE candidates between peers

For this, you can use anything. In this article we are going to use WebSockets for real time bi directional communication between client and server

Signalling setup ( Server code)

import asyncio
from aiohttp import web
import json

async def index(request):
    with open('index.html', 'r') as f:
        content = f.read()
    return web.Response(text=content, content_type='text/html')

async def websocket_handler(request):
    ws = web.WebSocketResponse()
    await ws.prepare(request)
    # Handle incoming WebSocket messages here
    return ws

app = web.Application()
app.router.add_get('/', index)
app.router.add_get('/ws', websocket_handler)

web.run_app(app)
  1. Handling Peer Connections and Media streams

Here we are going to create RTCPeerConnection object to manage the connection and the media streams

Server code example (Peer Connection)

from aiortc import RTCPeerConnection, RTCSessionDescription

pcs = set()  # Keep track of peer connections

async def websocket_handler(request):
    ws = web.WebSocketResponse()
    await ws.prepare(request)

    pc = RTCPeerConnection()
    pcs.add(pc)

    @pc.on("datachannel")
    def on_datachannel(channel):
        @channel.on("message")
        async def on_message(message):
            # Handle incoming messages
            pass

    async for msg in ws:
        if msg.type == web.WSMsgType.TEXT:
            data = json.loads(msg.data)

            if data["type"] == "offer":
                await pc.setRemoteDescription(RTCSessionDescription(
                    sdp=data["sdp"], type=data["type"]))
                answer = await pc.createAnswer()
                await pc.setLocalDescription(answer)
                await ws.send_json({
                    "type": pc.localDescription.type,
                    "sdp": pc.localDescription.sdp
                })

            elif data["type"] == "candidate":
                candidate = data["candidate"]
                await pc.addIceCandidate(candidate)
        elif msg.type == web.WSMsgType.ERROR:
            print(f'WebSocket connection closed with exception {ws.exception()}')

    pcs.discard(pc)
    return ws

  1. Incorporating TURN servers into ICE configuration

To handle the NAT traversal and ensure connectivity we need TURN servers.

In this article we are going with Metered TURN servers. Metered is a Global provider of TURN server

You can sign up for a free plan on Metered TURN servers that offers 50 GB monthly TURN server quota and there are paid plans also available

Steps:

  • Obtain the Credentials

Sign Up on Metered.ca/stun-turn and get your TURN credentials

On the Dashboard click on the Click here to generate your first credential button to create a new TURN server credential

Then click on the Instructions button to get your ICE server array.

You can also use the api key to enable TURN servers

  • Configure the ICE servers
iceServers: [
      {
        urls: "stun:metered.ca:80",
      },
      {
        urls: "turn:global.relay.metered.ca:80",
        username: "4efd284bf1075051a07466e7",
        credential: "PLm78gtgI6mKgm/j",
      },
      {
        urls: "turn:global.relay.metered.ca:80?transport=tcp",
        username: "4efd284bf1075051a07466e7",
        credential: "PLm78gtgI6mKgm/j",
      },
      {
        urls: "turn:global.relay.metered.ca:443",
        username: "4efd284bf1075051a07466e7",
        credential: "PLm78gtgI6mKgm/j",
      },
      {
        urls: "turns:global.relay.metered.ca:443?transport=tcp",
        username: "4efd284bf1075051a07466e7",
        credential: "PLm78gtgI6mKgm/j",
      },
  ]
pc = RTCPeerConnection(configuration={"iceServers": iceServers})
  1. Code Example illustrating the Key streps

Here is how we can integrate everything here

from aiohttp import web
import json
from aiortc import RTCPeerConnection, RTCSessionDescription

async def websocket_handler(request):
    ws = web.WebSocketResponse()
    await ws.prepare(request)

    turn_servers =  [
      {
        urls: "stun:metered.ca:80",
      },
      {
        urls: "turn:global.relay.metered.ca:80",
        username: "4efd284bf1075051a07466e7",
        credential: "PLm78gtgI6mKgm/j",
      },
      {
        urls: "turn:global.relay.metered.ca:80?transport=tcp",
        username: "4efd284bf1075051a07466e7",
        credential: "PLm78gtgI6mKgm/j",
      },
      {
        urls: "turn:global.relay.metered.ca:443",
        username: "4efd284bf1075051a07466e7",
        credential: "PLm78gtgI6mKgm/j",
      },
      {
        urls: "turns:global.relay.metered.ca:443?transport=tcp",
        username: "4efd284bf1075051a07466e7",
        credential: "PLm78gtgI6mKgm/j",
      },
  ]
    pc = RTCPeerConnection(configuration={"iceServers": turn_servers})

    @pc.on("iceconnectionstatechange")
    def on_iceconnectionstatechange():
        print("ICE connection state:", pc.iceConnectionState)

    # Rest of your handler code...

    return ws

Practical Implementation Tips

Network Considerations

  1. Managing NAT traversal with Metered.ca STUN/TURN Servers

  • STUN Servers: These help the client devices that are behind a NAT know their own IP address and port number. To learn more about STUN servers go to Stun Server: What is Session Traversal Utilities for NAT?

  • TURN Servers: TURN servers relay traffic from peer to per when direct communication is not possible due to NAT or firewall rules. To learn more about TURN servers go to: What is a TURN server?

  1. Ensuring Reliable and Low latency Connections
  • Automatic Geographic routing: Metered.ca has automatic geographical routing

Performance Optimization

  1. Using asyncio for concurrency management

  2. Media streams management best practices

Metered TURN servers

  1. API: TURN server management with powerful API. You can do things like Add/ Remove credentials via the API, Retrieve Per User / Credentials and User metrics via the API, Enable/ Disable credentials via the API, Retrive Usage data by date via the API.

  2. Global Geo-Location targeting: Automatically directs traffic to the nearest servers, for lowest possible latency and highest quality performance. less than 50 ms latency anywhere around the world

  3. Servers in all the Regions of the world: Toronto, Miami, San Francisco, Amsterdam, London, Frankfurt, Bangalore, Singapore,Sydney, Seoul, Dallas, New York

  4. Low Latency: less than 50 ms latency, anywhere across the world.

  5. Cost-Effective: pay-as-you-go pricing with bandwidth and volume discounts available.

  6. Easy Administration: Get usage logs, emails when accounts reach threshold limits, billing records and email and phone support.

  7. Standards Compliant: Conforms to RFCs 5389, 5769, 5780, 5766, 6062, 6156, 5245, 5768, 6336, 6544, 5928 over UDP, TCP, TLS, and DTLS.

  8. Multi‑Tenancy: Create multiple credentials and separate the usage by customer, or different apps. Get Usage logs, billing records and threshold alerts.

  9. Enterprise Reliability: 99.999% Uptime with SLA.

  10. Enterprise Scale: With no limit on concurrent traffic or total traffic. Metered TURN Servers provide Enterprise Scalability

  11. 5 GB/mo Free: Get 5 GB every month free TURN server usage with the Free Plan

  12. Runs on port 80 and 443

  13. Support TURNS + SSL to allow connections through deep packet inspection firewalls.

  14. Supports both TCP and UDP

  15. Free Unlimited STUN

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