fix: a network, pool or secret a VM needs is not stopped or deleted

Stopping a network cut the running VMs on it off, deleting one or a
secret kept the VMs that name it from starting, and stopping a pool
took the disks of running VMs away, all without a word. Each is now
refused with the VMs (and, for a secret, the pools) that need it:
stopping while a running VM uses it, deleting while a VM's definition
names it. A disk given by its file path does not need its pool's
definition. The API's pool stop is refused the same way.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

virtsecrets/tests/test_secret_in_use.py

@@ -0,0 +1,64 @@
+"""A secret a VM disk or a pool needs is not deleted: without it that VM or
+pool no longer starts. A disk or pool names its secret by UUID or by usage.
+libvirt's test driver has no secrets, so the connection is a mock."""
+
+from unittest.mock import MagicMock, patch
+
+from computes.models import Compute
+from django.contrib.auth import get_user_model
+from django.contrib.messages import get_messages
+from django.test import SimpleTestCase, TestCase
+from django.urls import reverse
+from vrtManager.util import OperationError
+from vrtManager.virtsecrets import wvmSecrets
+
+UUID = "8f2c0000-0000-4000-8000-000000000001"
+
+
+def libvirt_object(name, xml):
+    obj = MagicMock()
+    obj.name.return_value = name
+    obj.XMLDesc.return_value = xml
+    return obj
+
+
+def disk_vm(name, secret):
+    return libvirt_object(name, f"<domain><devices><disk type='network'><source protocol='rbd' name='rbd/{name}'/>"
+                                f"<auth username='libvirt'>{secret}</auth><target dev='vdb'/></disk></devices></domain>")
+
+
+class SecretInUseTests(SimpleTestCase):
+    def delete(self, domains=(), pools=()):
+        with patch("vrtManager.connection.connection_manager.get_connection") as get:
+            wvm = get.return_value
+            wvm.listAllDomains.return_value = list(domains)
+            wvm.listAllStoragePools.return_value = list(pools)
+            secret = wvm.secretLookupByUUIDString.return_value
+            secret.usageID.return_value = "client.libvirt secret"
+            wvmSecrets("host", "login", "pw", 1).delete_secret(UUID)
+        return secret
+
+    def test_a_secret_a_vm_disk_or_a_pool_names_is_not_deleted(self):
+        pool = libvirt_object("ceph-rbd", "<pool type='rbd'><source><auth type='ceph' username='libvirt'>"
+                                          "<secret usage='client.libvirt secret'/></auth></source></pool>")
+        with self.assertRaises(OperationError) as refused:
+            self.delete([disk_vm("db-2", f"<secret type='ceph' uuid='{UUID}'/>")], [pool])
+        self.assertIn("VMs db-2", str(refused.exception))
+        self.assertIn("pools ceph-rbd", str(refused.exception))
+
+    def test_an_unused_secret_is_deleted(self):
+        other = disk_vm("web-1", "<secret type='ceph' uuid='8f2c0000-0000-4000-8000-000000000002'/>")
+        self.delete([other]).undefine.assert_called_once_with()
+
+
+class SecretInUsePageTests(TestCase):
+    def test_the_page_says_who_needs_it(self):
+        compute = Compute.objects.create(name="secret-use", hostname="localhost", login="", password="", type=4)
+        self.client.force_login(get_user_model().objects.create_superuser("secret-use", "su@example.com", "pw"))
+        url = reverse("virtsecrets", args=[compute.id])
+        with patch("virtsecrets.views.wvmSecrets") as conn:
+            conn.return_value.get_secrets.return_value = []
+            conn.return_value.delete_secret.side_effect = OperationError(f"Secret {UUID} is used by VMs db-2")
+            response = self.client.post(url, {"delete": "", "uuid": UUID})
+        self.assertRedirects(response, url, fetch_redirect_response=False)
+        self.assertEqual([str(m) for m in get_messages(response.wsgi_request)], [f"Secret {UUID} is used by VMs db-2"])

virtsecrets/views.py

@@ -11,6 +11,7 @@ from libvirt import (
     VIR_SECRET_USAGE_TYPE_VOLUME,
     libvirtError,
 )
+from vrtManager.util import OperationError
 from vrtManager.virtsecrets import wvmSecrets
 
 from virtsecrets.forms import AddSecret
@@ -68,7 +69,10 @@ def secrets(request, compute_id):
                         messages.error(request, msg_err.as_text())
             if "delete" in request.POST:
                 uuid = request.POST.get("uuid", "")
-                conn.delete_secret(uuid)
+                try:
+                    conn.delete_secret(uuid)
+                except OperationError as err:  # a VM disk or a pool needs it
+                    messages.error(request, str(err))
                 return HttpResponseRedirect(request.get_full_path())
             if "set_value" in request.POST:
                 uuid = request.POST.get("uuid", "")