⚡️(api) add cache to prevent excessive drain from /stats endpoint

src/backend/core/api/client/viewsets.py

@@ -7,6 +7,8 @@
 from django.conf import settings
 from django.db.models import OuterRef, Q, Subquery, Value
 from django.db.models.functions import Coalesce
+from django.utils.decorators import method_decorator
+from django.views.decorators.cache import cache_page
 
 from rest_framework import (
     decorators,
@@ -596,6 +598,7 @@ class StatView(views.APIView):
 
     permission_classes = [AllowAny]
 
+    @method_decorator(cache_page(3600))
     def get(self, request):
         """
         GET /api/v1.0/stats/

src/backend/core/tests/test_api_stats.py

@@ -2,6 +2,8 @@
 Test stats endpoint
 """
 
+from django.core.cache import cache
+
 import pytest
 from rest_framework import status
 from rest_framework.test import APIClient
@@ -43,6 +45,7 @@ def test_api_stats__expected_count():
         10, domain=domains_models.MailDomain.objects.all()[1]
     )
 
+    cache.clear()  # clear cache to avoid interferences from previous tests
     response = APIClient().get("/api/v1.0/stats/")
     assert response.status_code == status.HTTP_200_OK
     assert response.json() == {
@@ -52,3 +55,16 @@ def test_api_stats__expected_count():
         "mailboxes": 10,
         "teams": 3,
     }
+
+
+def test_api_stats__cache_as_expected():
+    """Cache should prevent excessive calls."""
+    cache.clear()  # clear cache to avoid interferences from previous tests
+
+    core_factories.UserFactory.create_batch(2)
+    APIClient().get("/api/v1.0/stats/")
+
+    core_factories.UserFactory()  # There is now a total of 3 users
+
+    new_response = APIClient().get("/api/v1.0/stats/")
+    assert new_response.json()["total_users"] == 2