Support notification priority in FCM relay (#1630)

# What this PR does
Adds support for notification priority in FCM relay + add some tests on
FCM relay.

## Which issue(s) this PR fixes
Related to https://github.com/grafana/oncall/issues/1550 and
https://github.com/grafana/oncall/pull/1612.

## Checklist

- [x] Unit, integration, and e2e (if applicable) tests updated

No changelog update since notification priority is "Unreleased":
a2caeae3c7/CHANGELOG.md (unreleased)

engine/apps/mobile_app/fcm_relay.py

@@ -4,7 +4,7 @@ from celery.utils.log import get_task_logger
 from django.conf import settings
 from fcm_django.models import FCMDevice
 from firebase_admin.exceptions import FirebaseError
-from firebase_admin.messaging import APNSConfig, APNSPayload, Aps, ApsAlert, CriticalSound, Message
+from firebase_admin.messaging import AndroidConfig, APNSConfig, APNSPayload, Aps, ApsAlert, CriticalSound, Message
 from rest_framework import status
 from rest_framework.permissions import IsAuthenticated
 from rest_framework.response import Response
@@ -42,18 +42,19 @@ class FCMRelayView(APIView):
             token = request.data["token"]
             data = request.data["data"]
             apns = request.data["apns"]
+            android = request.data.get("android")  # optional
         except KeyError:
             return Response(status=status.HTTP_400_BAD_REQUEST)
 
-        fcm_relay_async.delay(token=token, data=data, apns=apns)
+        fcm_relay_async.delay(token=token, data=data, apns=apns, android=android)
         return Response(status=status.HTTP_200_OK)
 
 
 @shared_dedicated_queue_retry_task(
     autoretry_for=(Exception,), retry_backoff=True, max_retries=1 if settings.DEBUG else 5
 )
-def fcm_relay_async(token, data, apns):
-    message = Message(token=token, data=data, apns=deserialize_apns(apns))
+def fcm_relay_async(token, data, apns, android=None):
+    message = _get_message_from_request_data(token, data, apns, android)
 
     # https://firebase.google.com/docs/cloud-messaging/http-server-ref#interpret-downstream
     response = FCMDevice(registration_id=token).send_message(message)
@@ -63,7 +64,17 @@ def fcm_relay_async(token, data, apns):
         raise response
 
 
-def deserialize_apns(apns):
+def _get_message_from_request_data(token, data, apns, android):
+    """
+    Create Message object from JSON payload from OSS instance.
+    """
+
+    return Message(
+        token=token, data=data, apns=_deserialize_apns(apns), android=AndroidConfig(**android) if android else None
+    )
+
+
+def _deserialize_apns(apns):
     """
     Create APNSConfig object from JSON payload from OSS instance.
     """
@@ -95,5 +106,6 @@ def deserialize_apns(apns):
                 sound=sound,
                 custom_data=aps,
             )
-        )
+        ),
+        headers=apns.get("headers"),
     )

engine/apps/mobile_app/tests/test_fcm_relay.py

@@ -1,3 +1,4 @@
+import json
 from unittest.mock import patch
 
 import pytest
@@ -7,7 +8,8 @@ from firebase_admin.exceptions import FirebaseError
 from rest_framework import status
 from rest_framework.test import APIClient
 
-from apps.mobile_app.fcm_relay import FCMRelayThrottler, fcm_relay_async
+from apps.mobile_app.fcm_relay import FCMRelayThrottler, _get_message_from_request_data, fcm_relay_async
+from apps.mobile_app.tasks import _get_fcm_message
 
 
 @pytest.mark.django_db
@@ -88,3 +90,41 @@ def test_fcm_relay_async_retry():
     ):
         with pytest.raises(FirebaseError):
             fcm_relay_async(token="test_token", data={}, apns={})
+
+
+def test_get_message_from_request_data():
+    token = "test_token"
+    data = {"test_data_key": "test_data_value"}
+    apns = {"headers": {"apns-priority": "10"}, "payload": {"aps": {"thread-id": "test_thread_id"}}}
+    android = {"priority": "high"}
+    message = _get_message_from_request_data(token, data, apns, android)
+
+    assert message.token == "test_token"
+    assert message.data == {"test_data_key": "test_data_value"}
+    assert message.apns.headers == {"apns-priority": "10"}
+    assert message.apns.payload.aps.thread_id == "test_thread_id"
+    assert message.android.priority == "high"
+
+
+@pytest.mark.django_db
+def test_fcm_relay_serialize_deserialize(
+    make_organization_and_user, make_alert_receive_channel, make_alert_group, make_alert
+):
+    organization, user = make_organization_and_user()
+    device = FCMDevice.objects.create(user=user, registration_id="test_device_id")
+
+    alert_receive_channel = make_alert_receive_channel(organization=organization)
+    alert_group = make_alert_group(alert_receive_channel)
+    make_alert(alert_group=alert_group, raw_request_data={})
+
+    # Imitate sending a message to the FCM relay endpoint
+    original_message = _get_fcm_message(alert_group, user, device.registration_id, critical=False)
+    request_data = json.loads(str(original_message))
+
+    # Imitate receiving a message from the FCM relay endpoint
+    relayed_message = _get_message_from_request_data(
+        request_data["token"], request_data["data"], request_data["apns"], request_data["android"]
+    )
+
+    # Check that the message is the same after serialization and deserialization
+    assert json.loads(str(original_message)) == json.loads(str(relayed_message))