Libvirt driver create images even without meta

This patch allows the libvirt driver to call _create_image and
create instance directory and other needed images even when there is no
image metadata specified.

As an added bonus, this patch refactors the code of _create_image
method a bit to make it more clear to the reader when some of the images
will and will not be created, especially with regard to booting from
volume.

Fixes bug: 1124441
Fixes bug: 1131913
Fixes bug: 1123274

blueprint: improve-boot-from-volume

Change-Id: I5a028dc0585876d35be4fb86df3a423d89e054ee

1 files changed, 54 insertions, 1 deletions

diff --git a/nova/tests/test_libvirt.py b/nova/tests/test_libvirt.py
index 351c6b7dd..55b6aaec4 100644
--- a/nova/tests/test_libvirt.py
+++ b/nova/tests/test_libvirt.py
@@ -2578,7 +2578,7 @@ class LibvirtConnTestCase(test.TestCase):
         self.stubs.Set(conn, 'get_info', fake_get_info)
 
         conn.spawn(self.context, instance, None, [], None)
-        self.assertFalse(self.create_image_called)
+        self.assertTrue(self.create_image_called)
 
         conn.spawn(self.context,
                    instance,
@@ -2587,6 +2587,59 @@ class LibvirtConnTestCase(test.TestCase):
                    None)
         self.assertTrue(self.create_image_called)
 
+    def test_spawn_from_volume_calls_cache(self):
+        self.cache_called_for_disk = False
+
+        def fake_none(*args, **kwargs):
+            return
+
+        def fake_cache(*args, **kwargs):
+            if kwargs.get('image_id') == 'my_fake_image':
+                self.cache_called_for_disk = True
+
+        def fake_get_info(instance):
+            return {'state': power_state.RUNNING}
+
+        conn = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
+        self.stubs.Set(conn, 'to_xml', fake_none)
+
+        self.stubs.Set(imagebackend.Image, 'cache', fake_cache)
+        self.stubs.Set(conn, '_create_domain_and_network', fake_none)
+        self.stubs.Set(conn, 'get_info', fake_get_info)
+
+        block_device_info = {'root_device_name': '/dev/vda',
+                             'block_device_mapping': [
+                                {'mount_device': 'vda'}]}
+
+        # Volume-backed instance created without image
+        instance_ref = self.test_instance
+        instance_ref['image_ref'] = ''
+        instance_ref['root_device_name'] = '/dev/vda'
+        instance = db.instance_create(self.context, instance_ref)
+
+        conn.spawn(self.context, instance, None, [], None,
+                   block_device_info=block_device_info)
+        self.assertFalse(self.cache_called_for_disk)
+        db.instance_destroy(self.context, instance['uuid'])
+
+        # Booted from volume but with placeholder image
+        instance_ref = self.test_instance
+        instance_ref['image_ref'] = 'my_fake_image'
+        instance_ref['root_device_name'] = '/dev/vda'
+        instance = db.instance_create(self.context, instance_ref)
+
+        conn.spawn(self.context, instance, None, [], None,
+                   block_device_info=block_device_info)
+        self.assertFalse(self.cache_called_for_disk)
+        db.instance_destroy(self.context, instance['uuid'])
+
+        # Booted from an image
+        instance_ref['image_ref'] = 'my_fake_image'
+        instance = db.instance_create(self.context, instance_ref)
+        conn.spawn(self.context, instance, None, [], None)
+        self.assertTrue(self.cache_called_for_disk)
+        db.instance_destroy(self.context, instance['uuid'])
+
     def test_create_image_plain(self):
         gotFiles = []