tenants: really ensure default tenant cannot be deleted (#8875)

authentik/tenants/models.py

@@ -87,11 +87,6 @@ def save(self, *args, **kwargs):
             raise IntegrityError("Cannot create schema named template")
         super().save(*args, **kwargs)
 
-    def delete(self, *args, **kwargs):
-        if self.schema_name in ("public", "template"):
-            raise IntegrityError("Cannot delete schema public or template")
-        super().delete(*args, **kwargs)
-
     @property
     def serializer(self) -> Serializer:
         from authentik.tenants.api.tenants import TenantSerializer

authentik/tenants/signals.py

@@ -0,0 +1,14 @@
+"""authentik tenants signals"""
+
+from django.db import models
+from django.db.models.signals import pre_delete
+from django.dispatch import receiver
+from django_tenants.utils import get_public_schema_name
+
+from authentik.tenants.models import Tenant
+
+
+@receiver(pre_delete, sender=Tenant)
+def tenants_ensure_no_default_delete(sender, instance: Tenant, **kwargs):
+    if instance.schema_name == get_public_schema_name():
+        raise models.ProtectedError("Cannot delete schema public", instance)