Don't update alert group metrics when deleting an alert group (#3544)

# Which issue(s) this PR fixes

Fixes https://github.com/grafana/oncall-private/issues/2376

## Checklist

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

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Fix schedules invalid dates issue ([#support-escalations/issues/8084](https://github.com/grafana/support-escalations/issues/8084))
+- Fix issue related to updating alert group metrics when deleting an alert group via the public API by @joeyorlando ([#3544](https://github.com/grafana/oncall/pull/3544))
 
 ## v1.3.76 (2023-12-11)
 

engine/apps/alerts/models/alert_group.py

@@ -1191,8 +1191,6 @@ class AlertGroup(AlertGroupSlackRenderingMixin, EscalationSnapshotMixin, models.
     def delete_by_user(self, user: User):
         from apps.alerts.models import AlertGroupLogRecord
 
-        initial_state = self.state
-
         self.stop_escalation()
         # prevent creating multiple logs
         # filter instead of get_or_create cause it can be multiple logs of this type due deleting error
@@ -1222,10 +1220,9 @@ class AlertGroup(AlertGroupSlackRenderingMixin, EscalationSnapshotMixin, models.
         dependent_alerts = list(self.dependent_alert_groups.all())
 
         self.hard_delete()
-        # Update alert group state metric cache
-        self._update_metrics(organization_id=user.organization_id, previous_state=initial_state, state=None)
 
-        for dependent_alert_group in dependent_alerts:  # unattach dependent incidents
+        # unattach dependent incidents
+        for dependent_alert_group in dependent_alerts:
             dependent_alert_group.un_attach_by_delete()
 
     def hard_delete(self):

engine/apps/alerts/tasks/delete_alert_group.py

@@ -24,6 +24,8 @@ def delete_alert_group(alert_group_pk, user_pk):
         logger.debug("User not found, skipping delete_alert_group")
         return
 
+    logger.debug(f"User {user} is deleting alert group {alert_group} (channel: {alert_group.channel})")
+
     try:
         alert_group.delete_by_user(user)
     except SlackAPIRatelimitError as e:

engine/apps/alerts/tests/test_alert_group.py

@@ -577,3 +577,47 @@ def test_filter_active_alert_groups(
     assert active_alert_groups.count() == 2
     assert alert_group_active in active_alert_groups
     assert alert_group_active_silenced in active_alert_groups
+
+
+@patch("apps.alerts.models.AlertGroup.hard_delete")
+@patch("apps.alerts.models.AlertGroup.un_attach_by_delete")
+@patch("apps.alerts.models.AlertGroup.stop_escalation")
+@patch("apps.alerts.models.alert_group.alert_group_action_triggered_signal")
+@pytest.mark.django_db
+def test_delete_by_user(
+    mock_alert_group_action_triggered_signal,
+    _mock_stop_escalation,
+    _mock_un_attach_by_delete,
+    _mock_hard_delete,
+    make_organization_and_user,
+    make_alert_receive_channel,
+    make_alert_group,
+):
+    organization, user = make_organization_and_user()
+    alert_receive_channel = make_alert_receive_channel(organization)
+
+    alert_group = make_alert_group(alert_receive_channel)
+
+    # make a few dependent alert groups
+    dependent_alert_groups = [make_alert_group(alert_receive_channel, root_alert_group=alert_group) for _ in range(3)]
+
+    assert alert_group.log_records.filter(type=AlertGroupLogRecord.TYPE_DELETED).count() == 0
+
+    alert_group.delete_by_user(user)
+
+    assert alert_group.log_records.filter(type=AlertGroupLogRecord.TYPE_DELETED).count() == 1
+    deleted_log_record = alert_group.log_records.get(type=AlertGroupLogRecord.TYPE_DELETED)
+
+    alert_group.stop_escalation.assert_called_once_with()
+
+    mock_alert_group_action_triggered_signal.send.assert_called_once_with(
+        sender=alert_group.delete_by_user,
+        log_record=deleted_log_record.pk,
+        action_source=None,
+        force_sync=True,
+    )
+
+    alert_group.hard_delete.assert_called_once_with()
+
+    for dependent_alert_group in dependent_alert_groups:
+        dependent_alert_group.un_attach_by_delete.assert_called_with()