Fix resize when instance has no image

This patch makes it possible to resize an instance that has no image
supplied (was booted from volume), by avoiding calling the image service
and thus causing an uncaught exception, if there was no image suplied in
the first place.

Fixes bug: 1182114
blueprint: improve-boot-from-volume

Change-Id: I67d63a7aef699b555897582c74b04e857db7aafb

2 files changed, 21 insertions, 1 deletions

diff --git a/nova/compute/api.py b/nova/compute/api.py
index f31aefb9b..518678524 100644
--- a/nova/compute/api.py
+++ b/nova/compute/api.py
@@ -2020,7 +2020,11 @@ class API(base.Base):
             raise exception.FlavorNotFound(flavor_id=flavor_id)
 
         # NOTE(markwash): look up the image early to avoid auth problems later
-        image = self.image_service.show(context, instance['image_ref'])
+        image_ref = instance.get('image_ref')
+        if image_ref:
+            image = self.image_service.show(context, image_ref)
+        else:
+            image = {}
 
         if same_instance_type and flavor_id:
             raise exception.CannotResizeToSameFlavor()
diff --git a/nova/tests/compute/test_compute.py b/nova/tests/compute/test_compute.py
index 3101e3aa2..36a6a36a6 100644
--- a/nova/tests/compute/test_compute.py
+++ b/nova/tests/compute/test_compute.py
@@ -6155,6 +6155,22 @@ class ComputeAPITestCase(BaseTestCase):
                           self.context, instance)
         self.compute.terminate_instance(self.context, instance=instance)
 
+    def test_resize_no_image(self):
+        def _fake_prep_resize(_context, **args):
+            image = args['image']
+            self.assertEqual(image, {})
+
+        instance = self._create_fake_instance(params={'image_ref': ''})
+        instance = db.instance_get_by_uuid(self.context, instance['uuid'])
+        instance = jsonutils.to_primitive(instance)
+        self.compute.run_instance(self.context, instance=instance)
+
+        self.stubs.Set(self.compute_api.scheduler_rpcapi,
+                       'prep_resize', _fake_prep_resize)
+
+        self.compute_api.resize(self.context, instance, None)
+        self.compute.terminate_instance(self.context, instance=instance)
+
     def test_migrate(self):
         instance = self._create_fake_instance()
         instance = db.instance_get_by_uuid(self.context, instance['uuid'])