Don't update Slack user groups for deleted organizations (#2985)

# What this PR does

Make sure that Slack user groups are not getting updated for deleted
orgs.
Without this change, there could be issues with backends in multiple
clusters trying to update a single Slack user group after migrating an
org to another cluster (organizations get soft deleted from the original
cluster after migration).

## Which issue(s) this PR fixes

https://github.com/grafana/support-escalations/issues/6936

## 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] `CHANGELOG.md` updated (or `pr:no changelog` PR label added if not
required)

CHANGELOG.md

@@ -16,6 +16,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Enable email notification step by default on Helm by @vadimkerr ([#2975](https://github.com/grafana/oncall/pull/2975))
 - Handle slack resolution note errors consistently ([#2976](https://github.com/grafana/oncall/pull/2976))
 
+### Fixed
+
+- Don't update Slack user groups for deleted organizations by @vadimkerr ([#2985](https://github.com/grafana/oncall/pull/2985))
+
 ## v1.3.35 (2023-09-05)
 
 ### Fixed

engine/apps/slack/tasks.py

@@ -451,7 +451,12 @@ def start_update_slack_user_group_for_schedules():
     from apps.slack.models import SlackUserGroup
 
     user_group_pks = (
-        SlackUserGroup.objects.filter(oncall_schedules__isnull=False).distinct().values_list("pk", flat=True)
+        SlackUserGroup.objects.filter(
+            oncall_schedules__isnull=False,  # has oncall schedules connected
+            oncall_schedules__organization__deleted_at__isnull=True,  # organization is not deleted
+        )
+        .distinct()
+        .values_list("pk", flat=True)
     )
 
     for user_group_pk in user_group_pks:

engine/apps/slack/tests/test_user_group.py

@@ -2,9 +2,11 @@ from unittest.mock import PropertyMock, patch
 
 import pytest
 
-from apps.schedules.models.on_call_schedule import OnCallScheduleQuerySet
+from apps.schedules.models.on_call_schedule import OnCallScheduleQuerySet, OnCallScheduleWeb
 from apps.slack.client import SlackClientWithErrorHandling
 from apps.slack.models import SlackUserGroup
+from apps.slack.tasks import start_update_slack_user_group_for_schedules, update_slack_user_group_for_schedules
+from apps.user_management.models import Organization
 
 
 @pytest.mark.django_db
@@ -67,3 +69,25 @@ def test_update_oncall_members(
         with patch.object(SlackUserGroup, "update_members") as update_members_mock:
             user_group.update_oncall_members()
             update_members_mock.assert_called()
+
+
+@pytest.mark.django_db
+def test_start_update_slack_user_group_for_schedules_organization_deleted(
+    make_organization_with_slack_team_identity, make_slack_user_group, make_schedule
+):
+    organization, slack_team_identity = make_organization_with_slack_team_identity()
+    user_group = make_slack_user_group(slack_team_identity)
+    make_schedule(organization, schedule_class=OnCallScheduleWeb, user_group=user_group)
+
+    # check user group is updated
+    with patch.object(update_slack_user_group_for_schedules, "delay") as mock:
+        start_update_slack_user_group_for_schedules()
+        mock.assert_called_once_with(user_group_pk=user_group.pk)
+
+    # soft delete the organization
+    Organization.objects.filter(pk=organization.pk).delete()
+
+    # check user group is not updated for deleted organization
+    with patch.object(update_slack_user_group_for_schedules, "delay") as mock:
+        start_update_slack_user_group_for_schedules()
+        mock.assert_not_called()