diff --git a/glance/async_/flows/api_image_import.py b/glance/async_/flows/api_image_import.py
index a7ca79d4bf..ea79f99ebd 100644
--- a/glance/async_/flows/api_image_import.py
+++ b/glance/async_/flows/api_image_import.py
@@ -29,6 +29,7 @@ from taskflow.patterns import linear_flow as lf
 from taskflow import retry
 from taskflow import task
 
+from glance.api import common as api_common
 import glance.async_.flows._internal_plugins as internal_plugins
 import glance.async_.flows.plugins as import_plugins
 from glance.common import exception
@@ -301,6 +302,24 @@ class _ImportActions(object):
                 raise AttributeError('Setting %s is not allowed' % attr)
             setattr(self._image, attr, value)
 
+    def set_image_extra_properties(self, properties):
+        """Merge values into image extra_properties.
+
+        This allows a plugin to set additional properties on the image,
+        as long as those are outside the reserved namespace. Any keys
+        in the internal namespace will be dropped (and logged).
+
+        :param properties: A dict of properties to be merged in
+        """
+        for key, value in properties.items():
+            if key.startswith(api_common.GLANCE_RESERVED_NS):
+                LOG.warning(('Dropping %(key)s=%(val)s during metadata '
+                             'injection for %(image)s'),
+                            {'key': key, 'val': value,
+                             'image': self.image_id})
+            else:
+                self._image.extra_properties[key] = value
+
     def remove_location_for_store(self, backend):
         """Remove a location from an image given a backend store.
 
diff --git a/glance/tests/unit/async_/flows/test_api_image_import.py b/glance/tests/unit/async_/flows/test_api_image_import.py
index 48ed12a17c..027e680d5f 100644
--- a/glance/tests/unit/async_/flows/test_api_image_import.py
+++ b/glance/tests/unit/async_/flows/test_api_image_import.py
@@ -689,6 +689,47 @@ class TestImportActionWrapper(test_utils.BaseTestCase):
             self.assertRaises(AttributeError,
                               action.set_image_attribute, id='foo')
 
+    @mock.patch.object(import_flow, 'LOG')
+    def test_set_image_extra_properties(self, mock_log):
+        mock_repo = mock.MagicMock()
+        mock_image = mock_repo.get.return_value
+        mock_image.image_id = IMAGE_ID1
+        mock_image.extra_properties = {'os_glance_import_task': TASK_ID1}
+        mock_image.status = 'bar'
+        wrapper = import_flow.ImportActionWrapper(mock_repo, IMAGE_ID1,
+                                                  TASK_ID1)
+        # One banned property
+        with wrapper as action:
+            action.set_image_extra_properties({'os_glance_foo': 'bar'})
+        self.assertEqual({'os_glance_import_task': TASK_ID1},
+                         mock_image.extra_properties)
+
+        mock_log.warning.assert_called()
+        mock_log.warning.reset_mock()
+
+        # Two banned properties
+        with wrapper as action:
+            action.set_image_extra_properties({'os_glance_foo': 'bar',
+                                               'os_glance_baz': 'bat'})
+        self.assertEqual({'os_glance_import_task': TASK_ID1},
+                         mock_image.extra_properties)
+
+        mock_log.warning.assert_called()
+        mock_log.warning.reset_mock()
+
+        # One banned and one allowed property
+        with wrapper as action:
+            action.set_image_extra_properties({'foo': 'bar',
+                                               'os_glance_foo': 'baz'})
+        self.assertEqual({'foo': 'bar',
+                          'os_glance_import_task': TASK_ID1},
+                         mock_image.extra_properties)
+
+        mock_log.warning.assert_called_once_with(
+            'Dropping %(key)s=%(val)s during metadata injection for %(image)s',
+            {'key': 'os_glance_foo', 'val': 'baz',
+             'image': IMAGE_ID1})
+
     def test_drop_lock_for_task(self):
         mock_repo = mock.MagicMock()
         mock_repo.get.return_value.extra_properties = {