Add helper for logging into community turn server (#25)

* add credentials and docs

* lint

* update

backend/gradio_webrtc/credentials.py

@@ -0,0 +1,52 @@
+import os
+from typing import Literal
+
+import requests
+
+
+def get_hf_turn_credentials(token=None):
+    if token is None:
+        token = os.getenv("HF_TOKEN")
+    credentials = requests.get(
+        "https://freddyaboulton-turn-server-login.hf.space/credentials",
+        headers={"X-HF-Access-Token": token},
+    )
+    if not credentials.status_code == 200:
+        raise ValueError("Failed to get credentials from HF turn server")
+    return {
+        "iceServers": [
+            {
+                "urls": "turn:gradio-turn.com:80",
+                **credentials.json(),
+            },
+        ]
+    }
+
+
+def get_twilio_turn_credentials(twilio_sid=None, twilio_token=None):
+    try:
+        from twilio.rest import Client
+    except ImportError:
+        raise ImportError("Please install twilio with `pip install twilio`")
+
+    if not twilio_sid and not twilio_token:
+        twilio_sid = os.environ.get("TWILIO_ACCOUNT_SID")
+        twilio_token = os.environ.get("TWILIO_AUTH_TOKEN")
+
+    client = Client(twilio_sid, twilio_token)
+
+    token = client.tokens.create()
+
+    return {
+        "iceServers": token.ice_servers,
+        "iceTransportPolicy": "relay",
+    }
+
+
+def get_turn_credentials(method: Literal["hf", "twilio"] = "hf", **kwargs):
+    if method == "hf":
+        return get_hf_turn_credentials(**kwargs)
+    elif method == "twilio":
+        return get_twilio_turn_credentials(**kwargs)
+    else:
+        raise ValueError("Invalid method. Must be 'hf' or 'twilio'")