From c8d5397b0a671fddfa9b9c27bc7790a439a18caf Mon Sep 17 00:00:00 2001
From: Amit Uniyal <auniyal@redhat.com>
Date: Thu, 4 Aug 2022 13:42:14 +0000
Subject: [PATCH] Adds check for VM snapshot fail while quiesce

Added check if quiesce fails because libvirt fails to connect with
qemu guest agent inside instance

Closes-Bug: #1980720
Change-Id: I134a4060ace2678f76ae3606bf117c07194a8d92
---
 nova/api/openstack/compute/servers.py         |  2 ++
 nova/exception.py                             |  5 +++++
 .../regressions/test_bug_1980720.py           |  3 ++-
 nova/tests/unit/virt/libvirt/test_driver.py   | 20 +++++++++++++++++++
 nova/virt/libvirt/driver.py                   |  8 +++++++-
 5 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/nova/api/openstack/compute/servers.py b/nova/api/openstack/compute/servers.py
index 6a9bf1fa92..946d5a7042 100644
--- a/nova/api/openstack/compute/servers.py
+++ b/nova/api/openstack/compute/servers.py
@@ -1353,6 +1353,8 @@ class ServersController(wsgi.Controller):
         except exception.InstanceInvalidState as state_error:
             common.raise_http_conflict_for_instance_invalid_state(state_error,
                         'createImage', id)
+        except exception.InstanceQuiesceFailed as err:
+            raise exc.HTTPConflict(explanation=err.format_message())
         except exception.Invalid as err:
             raise exc.HTTPBadRequest(explanation=err.format_message())
         except exception.OverQuota as e:
diff --git a/nova/exception.py b/nova/exception.py
index 3d8e596312..cebaea4bee 100644
--- a/nova/exception.py
+++ b/nova/exception.py
@@ -217,6 +217,11 @@ class InvalidVIOMMUArchitecture(Invalid):
                 "but given architecture %(arch)s.")
 
 
+class InstanceQuiesceFailed(Invalid):
+    msg_fmt = _("Failed to quiesce instance: %(reason)s")
+    code = 409
+
+
 class InvalidConfiguration(Invalid):
     msg_fmt = _("Configuration is Invalid.")
 
diff --git a/nova/tests/functional/regressions/test_bug_1980720.py b/nova/tests/functional/regressions/test_bug_1980720.py
index 416137123f..ad2e6e6ba2 100644
--- a/nova/tests/functional/regressions/test_bug_1980720.py
+++ b/nova/tests/functional/regressions/test_bug_1980720.py
@@ -58,10 +58,11 @@ class LibvirtDriverTests(
             nova_fixtures.libvirt.Domain, 'fsFreeze'
         ) as mock_obj:
             ex = nova_fixtures.libvirt.libvirtError("Error")
+            ex.err = (nova_fixtures.libvirt.VIR_ERR_AGENT_UNRESPONSIVE,)
 
             mock_obj.side_effect = ex
             excep = self.assertRaises(
                     client.OpenStackApiException,
                     self._snapshot_server, server, "snapshot-1"
                 )
-            self.assertEqual(500, excep.response.status_code)
+            self.assertEqual(409, excep.response.status_code)
diff --git a/nova/tests/unit/virt/libvirt/test_driver.py b/nova/tests/unit/virt/libvirt/test_driver.py
index fee87d3bb5..1c5f79dc89 100644
--- a/nova/tests/unit/virt/libvirt/test_driver.py
+++ b/nova/tests/unit/virt/libvirt/test_driver.py
@@ -9244,6 +9244,26 @@ class LibvirtConnTestCase(test.NoDBTestCase,
                                              image_meta))
             mock_fsthaw.assert_called_once_with()
 
+    def test_set_quiesced_agent_connection_fails(self):
+        # This is require to mock guest host
+        self.create_fake_libvirt_mock(lookupByUUIDString=self.fake_lookup)
+
+        with mock.patch.object(FakeVirtDomain, "fsFreeze") as mock_fsfreeze:
+            error = fakelibvirt.make_libvirtError(
+                fakelibvirt.libvirtError,
+                "QEMU guest agent is not connected",
+                error_code=fakelibvirt.VIR_ERR_AGENT_UNRESPONSIVE)
+
+            mock_fsfreeze.side_effect = error
+            mock_fsfreeze.error_code = error.get_error_code()
+
+            drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI())
+            instance = objects.Instance(**self.test_instance)
+            image_meta = objects.ImageMeta.from_dict(
+                {"properties": {"hw_qemu_guest_agent": "yes", }})
+            self.assertRaises(exception.InstanceQuiesceFailed,
+                drvr._set_quiesced, self.context, instance, image_meta, True)
+
     def test_create_snapshot_metadata(self):
         base = objects.ImageMeta.from_dict(
             {'disk_format': 'raw'})
diff --git a/nova/virt/libvirt/driver.py b/nova/virt/libvirt/driver.py
index ce884dfe30..7306e4a4c2 100644
--- a/nova/virt/libvirt/driver.py
+++ b/nova/virt/libvirt/driver.py
@@ -3250,7 +3250,13 @@ class LibvirtDriver(driver.ComputeDriver):
                      '[Error Code %(error_code)s] %(ex)s')
                    % {'instance_name': instance.name,
                       'error_code': error_code, 'ex': err_msg})
-            raise exception.InternalError(msg)
+
+            if error_code == libvirt.VIR_ERR_AGENT_UNRESPONSIVE:
+                msg += (", libvirt cannot connect to the qemu-guest-agent"
+                    " inside the instance.")
+                raise exception.InstanceQuiesceFailed(reason=msg)
+            else:
+                raise exception.InternalError(msg)
 
     def quiesce(self, context, instance, image_meta):
         """Freeze the guest filesystems to prepare for snapshot.