fix: handle empty notification recipients

api/organisations/task_helpers.py

@@ -29,6 +29,14 @@ def send_api_flags_blocked_notification(organisation: Organisation) -> None:
         userorganisation__organisation=organisation,
     )
 
+    recipient_emails = list(recipient_list.values_list("email", flat=True))
+    if not recipient_emails:
+        logger.warning(
+            "notification.no_recipients_for_blocked_notification",
+            organisation__id=organisation.id,
+        )
+        return
+
     url = get_current_site_url()
     context = {
         "organisation": organisation,
@@ -43,7 +51,7 @@ def send_api_flags_blocked_notification(organisation: Organisation) -> None:
         subject="Flagsmith API use has been blocked due to overuse",
         message=render_to_string(message, context),
         from_email=settings.DEFAULT_FROM_EMAIL,
-        recipient_list=list(recipient_list.values_list("email", flat=True)),
+        recipient_list=recipient_emails,
         html_message=render_to_string(html_message, context),
         fail_silently=True,
     )
@@ -75,6 +83,21 @@ def _send_api_usage_notification(
         message = "organisations/api_usage_notification_limit.txt"
         html_message = "organisations/api_usage_notification_limit.html"
 
+    recipient_emails = list(recipient_list.values_list("email", flat=True))
+
+    if not recipient_emails:
+        logger.warning(
+            "notification.no_recipients",
+            organisation__id=organisation.id,
+            matched_threshold=matched_threshold,
+        )
+        OrganisationAPIUsageNotification.objects.create(
+            organisation=organisation,
+            percent_usage=matched_threshold,
+            notified_at=timezone.now(),
+        )
+        return
+
     url = get_current_site_url()
     context = {
         "organisation": organisation,
@@ -87,7 +110,7 @@ def _send_api_usage_notification(
         subject=f"Flagsmith API use has reached {matched_threshold}%",
         message=render_to_string(message, context),
         from_email=settings.DEFAULT_FROM_EMAIL,
-        recipient_list=list(recipient_list.values_list("email", flat=True)),
+        recipient_list=recipient_emails,
         html_message=render_to_string(html_message, context),
         fail_silently=True,
     )

api/tests/unit/organisations/test_unit_organisations_tasks.py

@@ -39,6 +39,7 @@
 from organisations.subscriptions.xero.metadata import XeroSubscriptionMetadata
 from organisations.task_helpers import (
     handle_api_usage_notification_for_organisation,
+    send_api_flags_blocked_notification,
 )
 from organisations.tasks import (  # type: ignore[attr-defined]
     ALERT_EMAIL_MESSAGE,
@@ -530,6 +531,45 @@ def test_handle_api_usage_notifications__usage_below_100_percent__sends_90_perce
     )
 
 
+@pytest.mark.django_db
+@pytest.mark.freeze_time("2023-01-19T09:09:47.325132+00:00")
+def test_handle_api_usage_notifications__no_admin_users__skips_notification(
+    mocker: MockerFixture,
+    mailoutbox: list[EmailMultiAlternatives],
+    log: StructuredLogCapture,
+    enable_features: EnableFeaturesFixture,
+) -> None:
+    # Given - an organisation with no users
+    organisation = Organisation.objects.create(name="No Users Org")
+    now = timezone.now()
+    organisation.subscription.plan = SCALE_UP
+    organisation.subscription.subscription_id = "fancy_id"
+    organisation.subscription.save()
+    OrganisationSubscriptionInformationCache.objects.create(
+        organisation=organisation,
+        allowed_30d_api_calls=100,
+        current_billing_term_starts_at=now - timedelta(days=45),
+        current_billing_term_ends_at=now + timedelta(days=320),
+        api_calls_30d=91,
+    )
+    mock_api_usage = mocker.patch(
+        "organisations.task_helpers.get_current_api_usage",
+    )
+    mock_api_usage.return_value = 91
+    enable_features("api_usage_alerting")
+
+    # When
+    handle_api_usage_notifications()
+
+    # Then - no email sent, warning logged
+    assert len(mailoutbox) == 0
+    assert any(e.get("event") == "notification.no_recipients" for e in log.events)
+    assert OrganisationAPIUsageNotification.objects.filter(
+        organisation=organisation,
+        percent_usage=91,
+    ).exists()
+
+
 @pytest.mark.freeze_time("2023-01-19T09:09:47.325132+00:00")
 def test_handle_api_usage_notifications__usage_below_alert_thresholds__sends_no_email(
     mocker: MockerFixture,
@@ -2136,3 +2176,27 @@ def test_update_organisation_subscription_information_cache__called__calls_updat
             SubscriptionCacheEntity.CHARGEBEE, SubscriptionCacheEntity.API_USAGE
         )
     ]
+
+
+@pytest.mark.django_db
+def test_send_api_flags_blocked_notification__no_recipients__skips_notification(
+    organisation: Organisation,
+    log: StructuredLogCapture,
+    mailoutbox: list[EmailMultiAlternatives],
+) -> None:
+    # Given
+    # Ensure no users are associated with the organisation
+    UserOrganisation.objects.filter(organisation=organisation).delete()
+
+    # When
+    send_api_flags_blocked_notification(organisation)
+
+    # Then
+    assert len(mailoutbox) == 0
+    assert log.events == [
+        {
+            "level": "warning",
+            "event": "notification.no_recipients_for_blocked_notification",
+            "organisation__id": organisation.id,
+        }
+    ]

docs/docs/deployment-self-hosting/observability/_events-catalogue.md

@@ -2,7 +2,7 @@
 ### `api_usage.notification.evaluated`
 
 Logged at `info` from:
- - `api/organisations/task_helpers.py:153`
+ - `api/organisations/task_helpers.py:171`
 
 Attributes:
  - `allowed_api_calls`
@@ -16,15 +16,32 @@ Attributes:
 ### `api_usage.notification.missing_billing_starts_at`
 
 Logged at `error` from:
- - `api/organisations/task_helpers.py:118`
+ - `api/organisations/task_helpers.py:136`
+
+Attributes:
+ - `organisation.id`
+
+### `api_usage.notification.no_recipients`
+
+Logged at `warning` from:
+ - `api/organisations/task_helpers.py:89`
+
+Attributes:
+ - `matched_threshold`
+ - `organisation.id`
+
+### `api_usage.notification.no_recipients_for_blocked_notification`
+
+Logged at `warning` from:
+ - `api/organisations/task_helpers.py:34`
 
 Attributes:
  - `organisation.id`
 
 ### `api_usage.notification.sent`
 
 Logged at `info` from:
- - `api/organisations/task_helpers.py:176`
+ - `api/organisations/task_helpers.py:194`
 
 Attributes:
  - `matched_threshold`