Integtation backsync endpoint (#4082)

# What this PR does
Adds endpoint for integration backsync
Related to https://github.com/grafana/oncall-private/issues/2542

## Checklist

- [x] Unit, integration, and e2e (if applicable) tests updated
- [x] Documentation added (or `pr:no public docs` PR label added if not
required)
- [x] Added the relevant release notes label (see labels prefixed w/
`release:`). These labels dictate how your PR will
    show up in the autogenerated release notes.

engine/apps/integrations/tests/test_integration_backsync.py

@@ -0,0 +1,62 @@
+from unittest.mock import PropertyMock, patch
+
+import pytest
+from django.core.cache import cache
+from django.urls import reverse
+from rest_framework import status
+from rest_framework.test import APIClient
+
+
+@pytest.mark.django_db
+def test_integration_backsync_endpoint(
+    make_organization,
+    make_alert_receive_channel,
+    make_token_for_integration,
+):
+    organization = make_organization()
+    alert_receive_channel = make_alert_receive_channel(organization=organization)
+    _, token = make_token_for_integration(alert_receive_channel, organization)
+
+    client = APIClient()
+    url = reverse("integrations:integration_backsync")
+
+    response = client.post(url, format="json", HTTP_AUTHORIZATION=token)
+    assert response.status_code == status.HTTP_200_OK
+
+
+@pytest.mark.django_db
+def test_integration_backsync_endpoint_wrong_token(
+    make_organization,
+    make_alert_receive_channel,
+):
+    client = APIClient()
+    url = reverse("integrations:integration_backsync")
+    response = client.post(url, format="json", HTTP_AUTHORIZATION="randomtesttoken")
+    assert response.status_code == status.HTTP_403_FORBIDDEN
+
+
+@pytest.mark.django_db
+def test_integration_backsync_endpoint_throttling(
+    make_organization,
+    make_alert_receive_channel,
+    make_token_for_integration,
+):
+    organization = make_organization()
+    alert_receive_channel = make_alert_receive_channel(organization=organization)
+    _, token = make_token_for_integration(alert_receive_channel, organization)
+
+    client = APIClient()
+    url = reverse("integrations:integration_backsync")
+    cache.clear()
+
+    with patch(
+        "apps.integrations.throttlers.integration_backsync_throttler.BacksyncRateThrottle.rate",
+        new_callable=PropertyMock,
+    ) as mocked_rate:
+        mocked_rate.return_value = "1/m"
+
+        response = client.post(url, format="json", HTTP_AUTHORIZATION=token)
+        assert response.status_code == status.HTTP_200_OK
+
+        response = client.post(url, format="json", HTTP_AUTHORIZATION=f"{token}")
+        assert response.status_code == status.HTTP_429_TOO_MANY_REQUESTS

engine/apps/integrations/throttlers/integration_backsync_throttler.py

@@ -0,0 +1,14 @@
+from rest_framework.throttling import SimpleRateThrottle
+
+
+class BacksyncRateThrottle(SimpleRateThrottle):
+    """
+    Integration backsync rate limit
+    """
+
+    scope = "backsync"
+    rate = "300/m"
+
+    def get_cache_key(self, request, view):
+        ident = request.auth.alert_receive_channel.pk
+        return self.cache_format % {"scope": self.scope, "ident": ident}

engine/apps/integrations/urls.py

@@ -11,6 +11,7 @@ from .views import (
     AmazonSNS,
     GrafanaAlertingAPIView,
     GrafanaAPIView,
+    IntegrationBacksyncAPIView,
     IntegrationHeartBeatAPIView,
     UniversalAPIView,
 )
@@ -32,6 +33,8 @@ urlpatterns = [
     path("alertmanager/<str:alert_channel_key>/", AlertManagerAPIView.as_view(), name="alertmanager"),
     path("amazon_sns/<str:alert_channel_key>/", AmazonSNS.as_view(), name="amazon_sns"),
     path("<str:integration_type>/<str:alert_channel_key>/", UniversalAPIView.as_view(), name="universal"),
+    # integration backsync
+    path("backsync/", IntegrationBacksyncAPIView.as_view(), name="integration_backsync"),
 ]
 
 if settings.FEATURE_INBOUND_EMAIL_ENABLED:

engine/apps/integrations/views.py

@@ -8,10 +8,12 @@ from django.utils import timezone
 from django.utils.decorators import method_decorator
 from django.views.decorators.csrf import csrf_exempt
 from django_sns_view.views import SNSEndpoint
+from rest_framework.permissions import IsAuthenticated
 from rest_framework.response import Response
 from rest_framework.views import APIView
 
 from apps.alerts.models import AlertReceiveChannel
+from apps.auth_token.auth import IntegrationBacksyncAuthentication
 from apps.heartbeat.tasks import process_heartbeat_task
 from apps.integrations.legacy_prefix import has_legacy_prefix
 from apps.integrations.mixins import (
@@ -22,6 +24,7 @@ from apps.integrations.mixins import (
     is_ratelimit_ignored,
 )
 from apps.integrations.tasks import create_alert, create_alertmanager_alerts
+from apps.integrations.throttlers.integration_backsync_throttler import BacksyncRateThrottle
 from apps.user_management.exceptions import OrganizationDeletedException, OrganizationMovedException
 from common.api_helpers.utils import create_engine_url
 
@@ -353,3 +356,16 @@ class IntegrationHeartBeatAPIView(AlertChannelDefiningMixin, IntegrationHeartBea
         process_heartbeat_task.apply_async(
             (alert_receive_channel.pk,),
         )
+
+
+class IntegrationBacksyncAPIView(APIView):
+    authentication_classes = (IntegrationBacksyncAuthentication,)
+    permission_classes = (IsAuthenticated,)
+    throttle_classes = (BacksyncRateThrottle,)
+
+    def post(self, request):
+        alert_receive_channel = request.auth.alert_receive_channel
+        integration_backsync_func = getattr(alert_receive_channel.config, "integration_backsync", None)
+        if integration_backsync_func:
+            integration_backsync_func(alert_receive_channel, request.data)
+        return Response(status=200)