openstack/nova
Code Issues Proposed changes

Fall back to flat config drive if not found in rbd

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Commit adecf780d3ed4315e4ce305cb1821d493650494b added support for
storing config drives in rbd. Existing instances however still
have config drives in the instance directory. If an existing
instance is stopped, an attempt to start it again fails because the
guest config is generated assuming a config drive location in rbd.

This adds a fall back to the instance directory in the case of
config drive and rbd if the image is not found in rbd.

Closes-Bug: #1582684

Change-Id: I21107ea0a148b66bee81e57cdce08e3006a60aee
This commit is contained in:
melanie witt 2016-05-18 00:09:18 +00:00
parent bbd347c8ec
commit f5c9ebd560
2 changed files with 39 additions and 0 deletions
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30
nova/tests/unit/virt/libvirt/test_driver.py
View File

@ -13765,6 +13765,36 @@ class LibvirtConnTestCase(test.NoDBTestCase):
self._test_get_guest_config_parallels_volume(vm_mode.EXE, 4)
self._test_get_guest_config_parallels_volume(vm_mode.HVM, 6)
def test_get_guest_disk_config_rbd_older_config_drive_fall_back(self):
# New config drives are stored in rbd but existing instances have
# config drives in the old location under the instances path.
# Test that the driver falls back to 'flat' for config drive if it
# doesn't exist in rbd.
self.flags(images_type='rbd', group='libvirt')
drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
drvr.image_backend = mock.Mock()
mock_rbd_image = mock.Mock()
mock_flat_image = mock.Mock()
mock_flat_image.libvirt_info.return_value = mock.sentinel.diskconfig
drvr.image_backend.image.side_effect = [mock_rbd_image,
mock_flat_image]
mock_rbd_image.exists.return_value = False
instance = objects.Instance()
disk_mapping = {'disk.config': {'bus': 'ide',
'dev': 'hdd',
'type': 'file'}}
flavor = objects.Flavor(extra_specs={})
diskconfig = drvr._get_guest_disk_config(
instance, 'disk.config', disk_mapping, flavor,
drvr._get_disk_config_image_type())
self.assertEqual(2, drvr.image_backend.image.call_count)
call1 = mock.call(instance, 'disk.config', 'rbd')
call2 = mock.call(instance, 'disk.config', 'flat')
drvr.image_backend.image.assert_has_calls([call1, call2])
self.assertEqual(mock.sentinel.diskconfig, diskconfig)
def _test_prepare_domain_for_snapshot(self, live_snapshot, state):
drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
instance_ref = objects.Instance(**self.test_instance)

9
nova/virt/libvirt/driver.py
View File

@ -3327,6 +3327,15 @@ class LibvirtDriver(driver.ComputeDriver):
image = self.image_backend.image(instance,
name,
image_type)
if (name == 'disk.config' and image_type == 'rbd' and
not image.exists()):
# This is likely an older config drive that has not been migrated
# to rbd yet. Try to fall back on 'flat' image type.
# TODO(melwitt): Add online migration of some sort so we can
# remove this fall back once we know all config drives are in rbd.
image = self.image_backend.image(instance, name, 'flat')
LOG.debug('Config drive not found in RBD, falling back to the '
'instance directory', instance=instance)
disk_info = disk_mapping[name]
return image.libvirt_info(disk_info['bus'],
disk_info['dev'],