for mobile app push notifications set FCM android priority to high (#1612)

# What this PR does

## Which issue(s) this PR fixes

## Checklist

- [ ] Unit, integration, and e2e (if applicable) tests updated (N/A)
- [ ] Documentation added (or `pr:no public docs` PR label added if not
required) (N/A)
- [x] `CHANGELOG.md` updated (or `pr:no changelog` PR label added if not
required)

CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - When the `DANGEROUS_WEBHOOKS_ENABLED` environment variable is set to true, it's possible now to create Outgoing Webhooks
   using URLs without a top-level domain ([1266](https://github.com/grafana/oncall/pull/1266))
 - Updated wording when creating an integration ([1572](https://github.com/grafana/oncall/pull/1572))
+- Set FCM iOS/Android "message priority" to "high priority" for mobile app push notifications ([1612](https://github.com/grafana/oncall/pull/1612))
 
 ## v1.2.1 (2023-03-23)
 

engine/apps/mobile_app/tasks.py

@@ -6,7 +6,7 @@ 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 requests import HTTPError
 from rest_framework import status
 
@@ -185,6 +185,21 @@ def _get_fcm_message(alert_group, user, registration_id, critical):
                 mobile_app_user_settings.important_notification_override_dnd
             ),
         },
+        android=AndroidConfig(
+            # from the docs
+            # https://firebase.google.com/docs/cloud-messaging/concept-options#setting-the-priority-of-a-message
+            #
+            # Normal priority.
+            # Normal priority messages are delivered immediately when the app is in the foreground.
+            # For backgrounded apps, delivery may be delayed. For less time-sensitive messages, such as notifications
+            # of new email, keeping your UI in sync, or syncing app data in the background, choose normal delivery
+            # priority.
+            #
+            # High priority.
+            # FCM attempts to deliver high priority messages immediately even if the device is in Doze mode.
+            # High priority messages are for time-sensitive, user visible content.
+            priority="high",
+        ),
         apns=APNSConfig(
             payload=APNSPayload(
                 aps=Aps(
@@ -201,6 +216,11 @@ def _get_fcm_message(alert_group, user, registration_id, critical):
                         "interruption-level": "critical" if critical else "time-sensitive",
                     },
                 ),
+                headers={
+                    # From the docs
+                    # https://firebase.google.com/docs/cloud-messaging/concept-options#setting-the-priority-of-a-message
+                    "apns-priority": "10",
+                },
             ),
         ),
     )