realm: Add uuid and associated secret columns.

Thisi and the following commit follow the approach used in
3e2ad84bbe.

First migration requires a server restart - after that any new realms
will be created with the columns set.

The following migrations are in the next commit:

Second migration does a backfill for older realms and can run in the
background while the server is operating normally.

Third migration enforces null=False now that all realms have the columns
set.

zerver/migrations/0479_realm_uuid_realm_uuid_owner_secret.py

@@ -0,0 +1,22 @@
+# Generated by Django 4.2.5 on 2023-10-06 09:21
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("zerver", "0478_realm_enable_guest_user_indicator"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="realm",
+            name="uuid",
+            field=models.UUIDField(null=True, unique=True),
+        ),
+        migrations.AddField(
+            model_name="realm",
+            name="uuid_owner_secret",
+            field=models.TextField(null=True),
+        ),
+    ]

zerver/models.py

@@ -275,6 +275,14 @@ class RealmAuthenticationMethod(models.Model):
         unique_together = ("realm", "name")
 
 
+def generate_realm_uuid_owner_secret() -> str:
+    token = generate_api_key()
+
+    # We include a prefix to facilitate scanning for accidental
+    # disclosure of secrets e.g. in Github commit pushes.
+    return f"zuliprealm_{token}"
+
+
 class Realm(models.Model):  # type: ignore[django-manager-missing] # django-stubs cannot resolve the custom CTEManager yet https://github.com/typeddjango/django-stubs/issues/1023
     MAX_REALM_NAME_LENGTH = 40
     MAX_REALM_DESCRIPTION_LENGTH = 1000
@@ -295,6 +303,11 @@ class Realm(models.Model):  # type: ignore[django-manager-missing] # django-stub
     # at `foo.example.com`.
     string_id = models.CharField(max_length=MAX_REALM_SUBDOMAIN_LENGTH, unique=True)
 
+    # uuid and a secret for the sake of per-realm authentication with the push notification
+    # bouncer.
+    uuid = models.UUIDField(default=uuid4, unique=True)
+    uuid_owner_secret = models.TextField(default=generate_realm_uuid_owner_secret)
+
     date_created = models.DateTimeField(default=timezone_now)
     demo_organization_scheduled_deletion_date = models.DateTimeField(default=None, null=True)
     deactivated = models.BooleanField(default=False)

zerver/tests/test_import_export.py

@@ -1,6 +1,7 @@
 import datetime
 import os
 import shutil
+import uuid
 from collections import defaultdict
 from typing import Any, Callable, Dict, FrozenSet, Iterable, List, Optional, Set, Tuple
 from unittest.mock import patch
@@ -329,6 +330,13 @@ class RealmImportExportTest(ExportFile):
                 consent_message_id=consent_message_id,
                 public_only=public_only,
             )
+
+            # This is a unique field and thus the cycle of export->import
+            # within the same server (which is what happens in our tests)
+            # will cause a conflict - so rotate it.
+            realm.uuid = uuid.uuid4()
+            realm.save()
+
             export_usermessages_batch(
                 input_path=os.path.join(output_dir, "messages-000001.json.partial"),
                 output_path=os.path.join(output_dir, "messages-000001.json"),
@@ -1538,25 +1546,31 @@ class RealmImportExportTest(ExportFile):
         self.export_realm(realm)
 
         with self.settings(BILLING_ENABLED=True), self.assertLogs(level="INFO"):
-            realm = do_import_realm(get_output_dir(), "test-zulip-1")
-            self.assertEqual(realm.plan_type, Realm.PLAN_TYPE_LIMITED)
-            self.assertEqual(realm.max_invites, 100)
-            self.assertEqual(realm.upload_quota_gb, 5)
-            self.assertEqual(realm.message_visibility_limit, 10000)
+            imported_realm = do_import_realm(get_output_dir(), "test-zulip-1")
+            self.assertEqual(imported_realm.plan_type, Realm.PLAN_TYPE_LIMITED)
+            self.assertEqual(imported_realm.max_invites, 100)
+            self.assertEqual(imported_realm.upload_quota_gb, 5)
+            self.assertEqual(imported_realm.message_visibility_limit, 10000)
             self.assertTrue(
                 RealmAuditLog.objects.filter(
-                    realm=realm, event_type=RealmAuditLog.REALM_PLAN_TYPE_CHANGED
+                    realm=imported_realm, event_type=RealmAuditLog.REALM_PLAN_TYPE_CHANGED
                 ).exists()
             )
+
+        # Importing the same export data twice would cause conflict on unique fields,
+        # so instead re-export the original realm via self.export_realm, which handles
+        # this issue.
+        self.export_realm(realm)
+
         with self.settings(BILLING_ENABLED=False), self.assertLogs(level="INFO"):
-            realm = do_import_realm(get_output_dir(), "test-zulip-2")
-            self.assertEqual(realm.plan_type, Realm.PLAN_TYPE_SELF_HOSTED)
-            self.assertEqual(realm.max_invites, 100)
-            self.assertEqual(realm.upload_quota_gb, None)
-            self.assertEqual(realm.message_visibility_limit, None)
+            imported_realm = do_import_realm(get_output_dir(), "test-zulip-2")
+            self.assertEqual(imported_realm.plan_type, Realm.PLAN_TYPE_SELF_HOSTED)
+            self.assertEqual(imported_realm.max_invites, 100)
+            self.assertEqual(imported_realm.upload_quota_gb, None)
+            self.assertEqual(imported_realm.message_visibility_limit, None)
             self.assertTrue(
                 RealmAuditLog.objects.filter(
-                    realm=realm, event_type=RealmAuditLog.REALM_PLAN_TYPE_CHANGED
+                    realm=imported_realm, event_type=RealmAuditLog.REALM_PLAN_TYPE_CHANGED
                 ).exists()
             )