🛂(backend) stop throttling collaboration servers

We observe some throttling pick here and there.
We observed that when the collaboration has a
problem, it is retrying to connect, leading to more
requests to the django backend. At one point, the
throttling is reached and the user would not
be able to use the application anymore.
Now when the request comes from a collaboration
server, we do not throttle it anymore.

src/backend/core/tests/test_api_throttling_document_throttle.py

@@ -0,0 +1,107 @@
+"""
+Test DocumentThrottle for regular throttling and y-provider bypass.
+"""
+
+import pytest
+from rest_framework.test import APIClient
+
+from core import factories
+
+pytestmark = pytest.mark.django_db
+
+
+def test_api_throttling_document_throttle_regular_requests(settings):
+    """Test that regular requests are throttled normally."""
+
+    current_rate = settings.REST_FRAMEWORK["DEFAULT_THROTTLE_RATES"]["document"]
+    settings.REST_FRAMEWORK["DEFAULT_THROTTLE_RATES"]["document"] = "3/minute"
+    settings.Y_PROVIDER_API_KEY = "test-y-provider-key"
+
+    user = factories.UserFactory()
+    client = APIClient()
+    client.force_login(user)
+
+    document = factories.DocumentFactory()
+    factories.UserDocumentAccessFactory(document=document, user=user)
+
+    # Make 3 requests without the y-provider key
+    for _i in range(3):
+        response = client.get(
+            f"/api/v1.0/documents/{document.id!s}/",
+        )
+        assert response.status_code == 200
+
+    # 4th request should be throttled
+    response = client.get(
+        f"/api/v1.0/documents/{document.id!s}/",
+    )
+    assert response.status_code == 429
+
+    # A request with the y-provider key should NOT be throttled
+    response = client.get(
+        f"/api/v1.0/documents/{document.id!s}/",
+        HTTP_X_Y_PROVIDER_KEY="test-y-provider-key",
+    )
+    assert response.status_code == 200
+
+    # Restore original rate
+    settings.REST_FRAMEWORK["DEFAULT_THROTTLE_RATES"]["document"] = current_rate
+
+
+def test_api_throttling_document_throttle_y_provider_exempted(settings):
+    """Test that y-provider requests are exempted from throttling."""
+
+    current_rate = settings.REST_FRAMEWORK["DEFAULT_THROTTLE_RATES"]["document"]
+    settings.REST_FRAMEWORK["DEFAULT_THROTTLE_RATES"]["document"] = "3/minute"
+    settings.Y_PROVIDER_API_KEY = "test-y-provider-key"
+
+    user = factories.UserFactory()
+    client = APIClient()
+    client.force_login(user)
+
+    document = factories.DocumentFactory()
+    factories.UserDocumentAccessFactory(document=document, user=user)
+
+    # Make many requests with the y-provider API key
+    for _i in range(10):
+        response = client.get(
+            f"/api/v1.0/documents/{document.id!s}/",
+            HTTP_X_Y_PROVIDER_KEY="test-y-provider-key",
+        )
+        assert response.status_code == 200
+
+    # Restore original rate
+    settings.REST_FRAMEWORK["DEFAULT_THROTTLE_RATES"]["document"] = current_rate
+
+
+def test_api_throttling_document_throttle_invalid_token(settings):
+    """Test that requests with invalid tokens are throttled."""
+
+    current_rate = settings.REST_FRAMEWORK["DEFAULT_THROTTLE_RATES"]["document"]
+    settings.REST_FRAMEWORK["DEFAULT_THROTTLE_RATES"]["document"] = "3/minute"
+    settings.Y_PROVIDER_API_KEY = "test-y-provider-key"
+
+    user = factories.UserFactory()
+    client = APIClient()
+    client.force_login(user)
+
+    document = factories.DocumentFactory()
+    factories.UserDocumentAccessFactory(document=document, user=user)
+
+    # Make 3 requests with an invalid token
+    for _i in range(3):
+        response = client.get(
+            f"/api/v1.0/documents/{document.id!s}/",
+            HTTP_X_Y_PROVIDER_KEY="invalid-token",
+        )
+        assert response.status_code == 200
+
+    # 4th request should be throttled
+    response = client.get(
+        f"/api/v1.0/documents/{document.id!s}/",
+        HTTP_X_Y_PROVIDER_KEY="invalid-token",
+    )
+    assert response.status_code == 429
+
+    # Restore original rate
+    settings.REST_FRAMEWORK["DEFAULT_THROTTLE_RATES"]["document"] = current_rate