Merge "libvirt: flatten rbd images when unshelving an instance" into stable/rocky

Author: Zuul

nova/tests/unit/virt/libvirt/test_driver.py

@@ -856,6 +856,7 @@ def _create_test_instance():
         'vcpu_model': None,
         'host': 'fake-host',
         'task_state': None,
+        'vm_state': None,
         'trusted_certs': None
     }
 
@@ -16910,8 +16911,8 @@ def fake_prepare(instance, name, tag):
         prepare.side_effect = fake_prepare
         drvr = libvirt_driver.LibvirtDriver(virtapi, False)
 
-        instance = objects.Instance(vm_state=vm_states.BUILDING,
-                                    **self.test_instance)
+        instance = objects.Instance(**self.test_instance)
+        instance.vm_state = vm_states.BUILDING
         vifs = [{'id': uuids.vif_1, 'active': False},
                 {'id': uuids.vif_2, 'active': False}]
 
@@ -18306,6 +18307,7 @@ def _create_instance(self, params=None):
         inst['system_metadata'] = {}
         inst['metadata'] = {}
         inst['task_state'] = None
+        inst['vm_state'] = None
 
         inst.update(params)
 
@@ -19289,6 +19291,54 @@ def test_is_booted_from_volume(self):
         bdm.append({'boot_index': 0})
         self.assertTrue(func(bdi))
 
+    def test_unshelve_noop_flatten_fetch_image_cache(self):
+        instance = self._create_instance(
+            params={'vm_state': vm_states.SHELVED_OFFLOADED})
+        drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
+        mock_imagebackend = mock.Mock(spec=imagebackend.Lvm)
+        mock_imagebackend.flatten.side_effect = NotImplementedError()
+
+        # Assert that this doesn't raise NotImplementedError
+        drvr._try_fetch_image_cache(mock_imagebackend, mock.sentinel.fetch,
+                self.context, mock.sentinel.filename, uuids.image_id,
+                instance, mock.sentinel.size)
+
+        # Assert that we cache and then flatten the image when an instance is
+        # still SHELVED_OFFLOADED during _try_fetch_image_cache.
+        mock_imagebackend.cache.assert_called_once_with(
+            fetch_func=mock.sentinel.fetch, context=self.context,
+            filename=mock.sentinel.filename, image_id=uuids.image_id,
+            size=mock.sentinel.size, trusted_certs=instance.trusted_certs)
+        mock_imagebackend.flatten.assert_called_once()
+
+    def test_unshelve_rbd_image_flatten_during_fetch_image_cache(self):
+        instance = self._create_instance(
+            params={'vm_state': vm_states.SHELVED_OFFLOADED})
+        drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
+        mock_rbd_driver = mock.Mock(spec=rbd_utils.RBDDriver)
+        mock_rbd_imagebackend = mock.Mock(spec=imagebackend.Rbd)
+        mock_rbd_imagebackend.rbd_name = mock.sentinel.rbd_name
+        mock_rbd_imagebackend.pool = mock.sentinel.rbd_pool
+        # This is logged so we can't use a sentinel
+        mock_rbd_imagebackend.path = 'rbd:pool/vol_disk'
+        mock_rbd_imagebackend.driver = mock_rbd_driver
+        mock_rbd_imagebackend.flatten.side_effect = \
+            imagebackend.Rbd.flatten(mock_rbd_imagebackend)
+
+        drvr._try_fetch_image_cache(mock_rbd_imagebackend, mock.sentinel.fetch,
+                self.context, mock.sentinel.filename, uuids.image_id,
+                instance, mock.sentinel.size)
+
+        # Assert that we cache and then flatten the image when an instance is
+        # still SHELVED_OFFLOADED during _try_fetch_image_cache.
+        mock_rbd_imagebackend.cache.assert_called_once_with(
+            fetch_func=mock.sentinel.fetch, context=self.context,
+            filename=mock.sentinel.filename, image_id=uuids.image_id,
+            size=mock.sentinel.size, trusted_certs=instance.trusted_certs)
+        mock_rbd_imagebackend.flatten.assert_called_once()
+        mock_rbd_driver.flatten.assert_called_once_with(
+            mock.sentinel.rbd_name, pool=mock.sentinel.rbd_pool)
+
     @mock.patch('nova.virt.libvirt.driver.imagebackend')
     @mock.patch('nova.virt.libvirt.driver.LibvirtDriver._inject_data')
     @mock.patch('nova.virt.libvirt.driver.imagecache')

nova/tests/unit/virt/libvirt/test_imagebackend.py

@@ -1550,6 +1550,12 @@ def get_mon_addrs():
             ["server1:1899", "server2:1920"]),
                          model)
 
+    @mock.patch.object(rbd_utils.RBDDriver, 'flatten')
+    def test_flatten(self, mock_flatten):
+        image = self.image_class(self.INSTANCE, self.NAME)
+        image.flatten()
+        mock_flatten.assert_called_once_with(image.rbd_name, pool=self.POOL)
+
     def test_import_file(self):
         image = self.image_class(self.INSTANCE, self.NAME)
 

nova/virt/libvirt/driver.py

@@ -7820,6 +7820,26 @@ def copy_from_host(target):
             image.cache(fetch_func=copy_from_host, size=size,
                         filename=filename)
 
+        # NOTE(lyarwood): If the instance vm_state is shelved offloaded then we
+        # must be unshelving for _try_fetch_image_cache to be called.
+        if instance.vm_state == vm_states.SHELVED_OFFLOADED:
+            # NOTE(lyarwood): When using the rbd imagebackend the call to cache
+            # above will attempt to clone from the shelved snapshot in Glance
+            # if available from this compute. We then need to flatten the
+            # resulting image to avoid it still referencing and ultimately
+            # blocking the removal of the shelved snapshot at the end of the
+            # unshelve. This is a no-op for all but the rbd imagebackend.
+            try:
+                image.flatten()
+                LOG.debug('Image %s flattened successfully while unshelving '
+                          'instance.', image.path, instance=instance)
+            except NotImplementedError:
+                # NOTE(lyarwood): There's an argument to be made for logging
+                # our inability to call flatten here, however given this isn't
+                # implemented for most of the backends it may do more harm than
+                # good, concerning operators etc so for now just pass.
+                pass
+
     def _create_images_and_backing(self, context, instance, instance_dir,
                                    disk_info, fallback_from_host=None):
         """:param context: security context

nova/virt/libvirt/imagebackend.py

@@ -431,6 +431,14 @@ def clone(self, context, image_id_or_uri):
         raise exception.ImageUnacceptable(image_id=image_id_or_uri,
                                           reason=reason)
 
+    def flatten(self):
+        """Flatten an image.
+
+        The implementation of this method is optional and therefore is
+        not an abstractmethod.
+        """
+        raise NotImplementedError('flatten() is not implemented')
+
     def direct_snapshot(self, context, snapshot_name, image_format, image_id,
                         base_image_id):
         """Prepare a snapshot for direct reference from glance.
@@ -961,6 +969,9 @@ def clone(self, context, image_id_or_uri):
         raise exception.ImageUnacceptable(image_id=image_id_or_uri,
                                           reason=reason)
 
+    def flatten(self):
+        self.driver.flatten(self.rbd_name, pool=self.pool)
+
     def get_model(self, connection):
         secret = None
         if CONF.libvirt.rbd_secret_uuid: