Use Twilio STUN/TURN servers

requirements.txt

@@ -1 +1,2 @@
 streamlit-webrtc
+twilio

turn.py

@@ -1,26 +1,34 @@
+# Copied from streamlit-webrtc/sample_utils/turn.py
 import logging
 import os
 
-import requests
 import streamlit as st
+from twilio.rest import Client
 
 logger = logging.getLogger(__name__)
 
 
-OPEN_RELAY_API_HOST = os.environ.get("OPEN_RELAY_API_HOST")
-OPEN_RELAY_API_KEY = os.environ.get("OPEN_RELAY_API_KEY")
-
-
-@st.cache_data
+@st.cache_data  # type: ignore
 def get_ice_servers():
-    if not OPEN_RELAY_API_HOST or not OPEN_RELAY_API_KEY:
+    """Use Twilio's TURN server because Streamlit Community Cloud has changed
+    its infrastructure and WebRTC connection cannot be established without TURN server now.  # noqa: E501
+    We considered Open Relay Project (https://www.metered.ca/tools/openrelay/) too,
+    but it is not stable and hardly works as some people reported like https://github.com/aiortc/aiortc/issues/832#issuecomment-1482420656  # noqa: E501
+    See https://github.com/whitphx/streamlit-webrtc/issues/1213
+    """
+
+    # Ref: https://www.twilio.com/docs/stun-turn/api
+    try:
+        account_sid = os.environ["TWILIO_ACCOUNT_SID"]
+        auth_token = os.environ["TWILIO_AUTH_TOKEN"]
+    except KeyError:
         logger.warning(
-            "Open Relay API host or key is not set. Fallback to a free STUN server from Google."  # noqa: E501
+            "Twilio credentials are not set. Fallback to a free STUN server from Google."  # noqa: E501
         )
         return [{"urls": ["stun:stun.l.google.com:19302"]}]
 
-    # Get response from Open Relay API
-    response = requests.get(
-        f"https://{OPEN_RELAY_API_HOST}/api/v1/turn/credentials?apiKey={OPEN_RELAY_API_KEY}"  # noqa: E501
-    )
-    return response.json()
+    client = Client(account_sid, auth_token)
+
+    token = client.tokens.create()
+
+    return token.ice_servers