🔒️(backend) throttle the start recording endpoint

Each recording start writes a Recording row and spins up a recording
worker, so a user or buggy client hammering the endpoint is costly even
when the calls end in a conflict or a worker failure.

Throttle it per authenticated user, mirroring room creation: a short-term
limit of 10/minute absorbs bursts and a daily cap of 100/day bounds
sustained use. Both are configurable via START_RECORDING_THROTTLE_RATES
and START_RECORDING_DAILY_THROTTLE_RATES.

Only starting a recording is throttled, as it is the costly action.
Stopping a recording only releases resources, so it is left unthrottled
and a throttled user can always stop an ongoing recording.

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to
 ### Added
 
 - ⚡️(backend) add UPPER(email) index for case-insensitive user lookups
+- 🔒️(backend) throttle the start recording endpoint
 
 ## [1.35.0] - 2026-10-13
 

docs/installation/kubernetes.md

@@ -335,6 +335,8 @@ These are the environmental options available on meet backend.
 | SESSION_COOKIE_AGE                              | Session cookie expiration in seconds                                                                                                                         | 43200 (12 hours)                                                                                                                                             |
 | ROOM_CREATION_THROTTLE_RATES                    | Room creation throttle rate per authenticated user | 50/minute                                                                                               | 50/minute                                                                                                                                                    |
 | ROOM_CREATION_DAILY_THROTTLE_RATES              | Daily room creation cap per authenticated user                                                                                                               | 1000/day                                                                                                                                                     |
+| START_RECORDING_THROTTLE_RATES                  | Recording start throttle rate per authenticated user                                                                                                         | 10/minute                                                                                                                                                    |
+| START_RECORDING_DAILY_THROTTLE_RATES            | Daily recording start cap per authenticated user                                                                                                             | 100/day                                                                                                                                                      |
 | REQUEST_ENTRY_THROTTLE_RATES                    | Entry request throttle rates                                                                                                                                 | 150/minute                                                                                                                                                   |
 | CREATION_CALLBACK_THROTTLE_RATES                | Creation callback throttle rates                                                                                                                             | 600/minute                                                                                                                                                   |
 | SPECTACULAR_SETTINGS_ENABLE_DJANGO_DEPLOY_CHECK | Enable Django deploy check                                                                                                                                   | false                                                                                                                                                        |

src/backend/core/api/throttling.py

@@ -47,6 +47,18 @@ class RoomCreationDailyUserRateThrottle(RoomCreationUserRateThrottle):
     scope = "room_creation_daily"
 
 
+class StartRecordingUserRateThrottle(MonitoredUserRateThrottle):
+    """Throttle recording starts per authenticated user."""
+
+    scope = "start_recording"
+
+
+class StartRecordingDailyUserRateThrottle(StartRecordingUserRateThrottle):
+    """Cap recording starts per authenticated user over a day."""
+
+    scope = "start_recording_daily"
+
+
 class RequestEntryAuthenticatedUserRateThrottle(MonitoredUserRateThrottle):
     """Throttle authenticated user requesting room entry"""
 

src/backend/core/api/viewsets.py

@@ -406,6 +406,10 @@ class RoomViewSet(
         permission_classes=[
             permissions.HasPrivilegesOnRoom,
         ],
+        throttle_classes=[
+            throttling.StartRecordingUserRateThrottle,
+            throttling.StartRecordingDailyUserRateThrottle,
+        ],
     )
     @FeatureFlag.require("recording")
     def start_room_recording(self, request, pk=None):  # pylint: disable=unused-argument

src/backend/core/tests/rooms/test_api_rooms_start_recording_throttling.py

@@ -0,0 +1,212 @@
+"""
+Test rooms API endpoints in the Meet core app: start recording throttling.
+"""
+
+# pylint: disable=redefined-outer-name,unused-argument
+
+from unittest import mock
+
+import pytest
+from rest_framework.test import APIClient
+
+from ...api.throttling import (
+    StartRecordingDailyUserRateThrottle,
+    StartRecordingUserRateThrottle,
+)
+from ...factories import RoomFactory, UserFactory
+from ...models import Recording
+
+pytestmark = pytest.mark.django_db
+
+
+@pytest.fixture
+def start_recording_throttle(monkeypatch):
+    """Lower the start recording rates."""
+    rates = StartRecordingUserRateThrottle.THROTTLE_RATES
+    monkeypatch.setitem(rates, "start_recording", "2/minute")
+    monkeypatch.setitem(rates, "start_recording_daily", "100/day")
+
+
+@pytest.fixture
+def daily_start_recording_throttle(monkeypatch):
+    """Lower the daily start recording rate and control the clock."""
+    rates = StartRecordingDailyUserRateThrottle.THROTTLE_RATES
+    monkeypatch.setitem(rates, "start_recording", "100/minute")
+    monkeypatch.setitem(rates, "start_recording_daily", "3/day")
+    now = [1_000_000.0]
+    monkeypatch.setattr(StartRecordingUserRateThrottle, "timer", lambda self: now[0])
+    return now
+
+
+@mock.patch("core.api.viewsets.WorkerServiceMediator")
+@mock.patch("core.api.viewsets.get_worker_service")
+def test_start_recording_throttled(
+    mock_get_worker_service, mock_mediator_class, start_recording_throttle, settings
+):
+    """Starting a recording should return 429 when exceeding the per-minute rate."""
+    settings.RECORDING_ENABLE = True
+    user = UserFactory()
+    client = APIClient()
+    client.force_login(user)
+
+    for _ in range(2):
+        room = RoomFactory(users=[(user, "owner")])
+        response = client.post(
+            f"/api/v1.0/rooms/{room.id}/start-recording/",
+            {"mode": "screen_recording"},
+        )
+        assert response.status_code == 201
+
+    room = RoomFactory(users=[(user, "owner")])
+    response = client.post(
+        f"/api/v1.0/rooms/{room.id}/start-recording/",
+        {"mode": "screen_recording"},
+    )
+
+    assert response.status_code == 429
+    assert 0 < int(response["Retry-After"]) <= 60
+    assert Recording.objects.count() == 2
+    assert mock_mediator_class.return_value.start.call_count == 2
+
+
+@mock.patch("core.api.viewsets.WorkerServiceMediator")
+@mock.patch("core.api.viewsets.get_worker_service")
+def test_start_recording_throttle_counts_failed_attempts(
+    mock_get_worker_service, mock_mediator_class, start_recording_throttle, settings
+):
+    """Failed recording starts should count toward the rate."""
+    settings.RECORDING_ENABLE = True
+    user = UserFactory()
+    room = RoomFactory(users=[(user, "owner")])
+    Recording.objects.create(room=room, mode="screen_recording", status="active")
+    client = APIClient()
+    client.force_login(user)
+
+    for _ in range(2):
+        response = client.post(
+            f"/api/v1.0/rooms/{room.id}/start-recording/",
+            {"mode": "screen_recording"},
+        )
+        assert response.status_code == 409
+
+    response = client.post(
+        f"/api/v1.0/rooms/{room.id}/start-recording/",
+        {"mode": "screen_recording"},
+    )
+
+    assert response.status_code == 429
+
+
+@mock.patch("core.api.viewsets.WorkerServiceMediator")
+@mock.patch("core.api.viewsets.get_worker_service")
+def test_start_recording_throttle_per_user(
+    mock_get_worker_service, mock_mediator_class, start_recording_throttle, settings
+):
+    """Starting a recording should succeed when another user is throttled."""
+    settings.RECORDING_ENABLE = True
+    client = APIClient()
+
+    user = UserFactory()
+    client.force_login(user)
+    for _ in range(2):
+        room = RoomFactory(users=[(user, "owner")])
+        response = client.post(
+            f"/api/v1.0/rooms/{room.id}/start-recording/",
+            {"mode": "screen_recording"},
+        )
+        assert response.status_code == 201
+
+    room = RoomFactory(users=[(user, "owner")])
+    response = client.post(
+        f"/api/v1.0/rooms/{room.id}/start-recording/",
+        {"mode": "screen_recording"},
+    )
+    assert response.status_code == 429
+
+    other_user = UserFactory()
+    client.force_login(other_user)
+    room = RoomFactory(users=[(other_user, "owner")])
+    response = client.post(
+        f"/api/v1.0/rooms/{room.id}/start-recording/",
+        {"mode": "screen_recording"},
+    )
+
+    assert response.status_code == 201
+
+
+@mock.patch("core.api.viewsets.WorkerServiceMediator")
+@mock.patch("core.api.viewsets.get_worker_service")
+def test_start_recording_throttle_does_not_limit_other_actions(
+    mock_get_worker_service, mock_mediator_class, start_recording_throttle, settings
+):
+    """Other room actions should succeed when starting a recording is throttled."""
+    settings.RECORDING_ENABLE = True
+    user = UserFactory()
+    client = APIClient()
+    client.force_login(user)
+
+    rooms = RoomFactory.create_batch(3, users=[(user, "owner")])
+    for room in rooms[:2]:
+        response = client.post(
+            f"/api/v1.0/rooms/{room.id}/start-recording/",
+            {"mode": "screen_recording"},
+        )
+        assert response.status_code == 201
+
+    response = client.post(
+        f"/api/v1.0/rooms/{rooms[2].id}/start-recording/",
+        {"mode": "screen_recording"},
+    )
+    assert response.status_code == 429
+
+    Recording.objects.filter(room=rooms[0]).update(status="active")
+    response = client.post(f"/api/v1.0/rooms/{rooms[0].id}/stop-recording/")
+    assert response.status_code == 200
+
+    response = client.get("/api/v1.0/rooms/")
+    assert response.status_code == 200
+
+    response = client.post("/api/v1.0/rooms/", {"name": "New room"})
+    assert response.status_code == 201
+
+
+@mock.patch("core.api.viewsets.WorkerServiceMediator")
+@mock.patch("core.api.viewsets.get_worker_service")
+def test_start_recording_daily_throttled(
+    mock_get_worker_service,
+    mock_mediator_class,
+    daily_start_recording_throttle,
+    settings,
+):
+    """Starting a recording should return 429 when exceeding the daily rate."""
+    settings.RECORDING_ENABLE = True
+    now = daily_start_recording_throttle
+    user = UserFactory()
+    client = APIClient()
+    client.force_login(user)
+
+    for _ in range(3):
+        room = RoomFactory(users=[(user, "owner")])
+        response = client.post(
+            f"/api/v1.0/rooms/{room.id}/start-recording/",
+            {"mode": "screen_recording"},
+        )
+        assert response.status_code == 201
+        now[0] += 120
+
+    room = RoomFactory(users=[(user, "owner")])
+    response = client.post(
+        f"/api/v1.0/rooms/{room.id}/start-recording/",
+        {"mode": "screen_recording"},
+    )
+    assert response.status_code == 429
+    assert 60 < int(response["Retry-After"]) <= 86400
+
+    now[0] += 86400
+    room = RoomFactory(users=[(user, "owner")])
+    response = client.post(
+        f"/api/v1.0/rooms/{room.id}/start-recording/",
+        {"mode": "screen_recording"},
+    )
+
+    assert response.status_code == 201

src/backend/meet/settings.py

@@ -395,6 +395,16 @@ class Base(Configuration):
                 environ_name="ROOM_CREATION_DAILY_THROTTLE_RATES",
                 environ_prefix=None,
             ),
+            "start_recording": values.Value(
+                default="10/minute",
+                environ_name="START_RECORDING_THROTTLE_RATES",
+                environ_prefix=None,
+            ),
+            "start_recording_daily": values.Value(
+                default="100/day",
+                environ_name="START_RECORDING_DAILY_THROTTLE_RATES",
+                environ_prefix=None,
+            ),
             "request_entry": values.Value(
                 default="150/minute",
                 environ_name="REQUEST_ENTRY_THROTTLE_RATES",