libvirt: Load and cache volume drivers on-demand
This change completes a long standing TODO in the libvirt driver where volume drivers had previously been loaded at startup. While quick this can result in drivers being dropped from the resulting list on hosts that don't support the underlying connector protocols as checked in os-brick. We should instead load and cache these drivers on-demand ensuring the same instance is reused by repeat callers to _get_volume_driver. An additional TODO is left in place to make this dict configurable in the future, allowing drivers to be replaced by different volume driver implementations. An example being the replacment of the os-brick `iscsi` volume driver with a native `iscsi` QEMU driver. Change-Id: If02a263055376442a116d00c18a1599b436f21d2
This commit is contained in:
Lee Yarwood
parent
0f558749d1
commit
684780ac0d
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@ -694,6 +694,11 @@ class VolumeDriverNotFound(NotFound):
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msg_fmt = _("Could not find a handler for %(driver_type)s volume.")
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class VolumeDriverNotSupported(VolumeDriverNotFound):
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msg_fmt = _("The %(volume_driver)s volume driver is not supported on this "
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"platform.")
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class InvalidImageRef(Invalid):
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msg_fmt = _("Invalid image href %(image_href)s.")
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@ -24846,31 +24846,78 @@ class LibvirtDriverTestCase(test.NoDBTestCase, TraitsComparisonMixin):
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self.assertRaises(fakelibvirt.libvirtError,
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self.drvr.trigger_crash_dump, instance)
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@mock.patch.object(libvirt_driver.LOG, 'debug')
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def test_get_volume_driver_invalid_connector_exception(self, mock_debug):
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"""Tests that the driver doesn't fail to initialize if one of the
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imported volume drivers raises InvalidConnectorProtocol from os-brick.
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"""
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# make a copy of the normal list and add a volume driver that raises
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# the handled os-brick exception when imported.
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libvirt_volume_drivers_copy = copy.copy(
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libvirt_driver.libvirt_volume_drivers)
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libvirt_volume_drivers_copy.append(
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'invalid=nova.tests.unit.virt.libvirt.test_driver.'
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'FakeInvalidVolumeDriver'
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def test_get_volume_driver_invalid_type(self):
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# Assert that VolumeDriverNotFound is raised when an invalid type is
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# provided in the connection_info
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self.assertRaises(
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exception.VolumeDriverNotFound,
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self.drvr._get_volume_driver,
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{'driver_volume_type': 'foo'}
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)
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with mock.patch.object(libvirt_driver, 'libvirt_volume_drivers',
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libvirt_volume_drivers_copy):
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drvr = libvirt_driver.LibvirtDriver(
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fake.FakeVirtAPI(), read_only=True
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)
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# make sure we didn't register the invalid volume driver
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self.assertNotIn('invalid', drvr.volume_drivers)
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# make sure we logged something
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mock_debug.assert_called_with(
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('Unable to load volume driver %s. '
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'It is not supported on this host.'),
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'nova.tests.unit.virt.libvirt.test_driver.FakeInvalidVolumeDriver'
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# Assert that VolumeDriverNotFound is raised when driver_volume_type
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# is missing in the provided connection_info.
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self.assertRaises(
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exception.VolumeDriverNotFound,
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self.drvr._get_volume_driver,
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{}
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)
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@mock.patch('oslo_utils.importutils.import_class')
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def test_get_volume_driver(self, mock_import_class):
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# Assert the behaviour of _get_volume_driver and the driver cache
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# Use a valid VOLUME_DRIVERS key but mock out the import of the class
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driver_volume_type = 'iscsi'
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connection_info = {
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'driver_volume_type': driver_volume_type
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}
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mock_driver = mock.Mock()
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mock_class = mock.Mock(return_value=mock_driver)
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mock_import_class.return_value = mock_class
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# Assert that the cache is empty
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self.assertEqual(0, len(self.drvr.volume_drivers))
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# Assert that repeat calls return the same instance of mock_driver
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self.assertEqual(
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mock_driver,
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self.drvr._get_volume_driver(connection_info)
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)
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self.assertEqual(
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mock_driver,
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self.drvr._get_volume_driver(connection_info)
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)
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# Assert that we only imported the class once
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mock_import_class.assert_called_once_with(
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libvirt_driver.VOLUME_DRIVERS.get('iscsi'))
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# Assert that the cache only contains the mock_driver instance
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self.assertEqual(1, len(self.drvr.volume_drivers))
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self.assertEqual(
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mock_driver,
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self.drvr.volume_drivers.get(driver_volume_type)
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)
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@mock.patch('oslo_utils.importutils.import_class')
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def test_get_volume_driver_unsupported_protocol(self, mock_import_class):
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# Assert that VolumeDriverNotSupported is raised when os-brick raises
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# InvalidConnectorProtocol while building the connector
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connection_info = {
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'driver_volume_type': 'iscsi'
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}
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mock_driver = mock.Mock(
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side_effect=brick_exception.InvalidConnectorProtocol)
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mock_class = mock.Mock(side_effect=mock_driver)
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mock_import_class.return_value = mock_class
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ex = self.assertRaises(
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exception.VolumeDriverNotSupported,
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self.drvr._get_volume_driver,
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connection_info
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)
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self.assertIn('volume driver is not supported on this platform',
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str(ex)
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)
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@mock.patch('nova.virt.libvirt.driver.LibvirtDriver'
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@ -127,6 +127,7 @@ from nova.virt.libvirt import vif as libvirt_vif
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from nova.virt.libvirt.volume import fs
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from nova.virt.libvirt.volume import mount
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from nova.virt.libvirt.volume import remotefs
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from nova.virt.libvirt.volume import volume
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from nova.virt import netutils
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from nova.volume import cinder
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@ -172,25 +173,27 @@ class InjectionInfo(collections.namedtuple(
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'admin_pass=<SANITIZED>)') % (self.network_info, self.files)
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libvirt_volume_drivers = [
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'iscsi=nova.virt.libvirt.volume.iscsi.LibvirtISCSIVolumeDriver',
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'iser=nova.virt.libvirt.volume.iser.LibvirtISERVolumeDriver',
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'local=nova.virt.libvirt.volume.volume.LibvirtVolumeDriver',
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'fake=nova.virt.libvirt.volume.volume.LibvirtFakeVolumeDriver',
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'rbd=nova.virt.libvirt.volume.net.LibvirtNetVolumeDriver',
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'nfs=nova.virt.libvirt.volume.nfs.LibvirtNFSVolumeDriver',
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'smbfs=nova.virt.libvirt.volume.smbfs.LibvirtSMBFSVolumeDriver',
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'fibre_channel='
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'nova.virt.libvirt.volume.fibrechannel.'
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'LibvirtFibreChannelVolumeDriver',
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'gpfs=nova.virt.libvirt.volume.gpfs.LibvirtGPFSVolumeDriver',
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'quobyte=nova.virt.libvirt.volume.quobyte.LibvirtQuobyteVolumeDriver',
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'scaleio=nova.virt.libvirt.volume.scaleio.LibvirtScaleIOVolumeDriver',
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'vzstorage='
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'nova.virt.libvirt.volume.vzstorage.LibvirtVZStorageVolumeDriver',
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'storpool=nova.virt.libvirt.volume.storpool.LibvirtStorPoolVolumeDriver',
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'nvmeof=nova.virt.libvirt.volume.nvme.LibvirtNVMEVolumeDriver',
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]
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# NOTE(lyarwood): Dict of volume drivers supported by the libvirt driver, keyed
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# by the connection_info['driver_volume_type'] returned by Cinder for each
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# volume type it supports
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# TODO(lyarwood): Add host configurables to allow this list to be changed.
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# Allowing native iSCSI to be reintroduced etc.
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VOLUME_DRIVERS = {
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'iscsi': 'nova.virt.libvirt.volume.iscsi.LibvirtISCSIVolumeDriver',
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'iser': 'nova.virt.libvirt.volume.iser.LibvirtISERVolumeDriver',
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'local': 'nova.virt.libvirt.volume.volume.LibvirtVolumeDriver',
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'fake': 'nova.virt.libvirt.volume.volume.LibvirtFakeVolumeDriver',
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'rbd': 'nova.virt.libvirt.volume.net.LibvirtNetVolumeDriver',
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'nfs': 'nova.virt.libvirt.volume.nfs.LibvirtNFSVolumeDriver',
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'smbfs': 'nova.virt.libvirt.volume.smbfs.LibvirtSMBFSVolumeDriver',
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'fibre_channel': 'nova.virt.libvirt.volume.fibrechannel.LibvirtFibreChannelVolumeDriver', # noqa:E501
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'gpfs': 'nova.virt.libvirt.volume.gpfs.LibvirtGPFSVolumeDriver',
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'quobyte': 'nova.virt.libvirt.volume.quobyte.LibvirtQuobyteVolumeDriver',
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'scaleio': 'nova.virt.libvirt.volume.scaleio.LibvirtScaleIOVolumeDriver',
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'vzstorage': 'nova.virt.libvirt.volume.vzstorage.LibvirtVZStorageVolumeDriver', # noqa:E501
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'storpool': 'nova.virt.libvirt.volume.storpool.LibvirtStorPoolVolumeDriver', # noqa:E501
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'nvmeof': 'nova.virt.libvirt.volume.nvme.LibvirtNVMEVolumeDriver',
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}
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def patch_tpool_proxy():
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@ -319,11 +322,8 @@ class LibvirtDriver(driver.ComputeDriver):
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self.vif_driver = libvirt_vif.LibvirtGenericVIFDriver()
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# TODO(mriedem): Long-term we should load up the volume drivers on
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# demand as needed rather than doing this on startup, as there might
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# be unsupported volume drivers in this list based on the underlying
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# platform.
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self.volume_drivers = self._get_volume_drivers()
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# NOTE(lyarwood): Volume drivers are loaded on-demand
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self.volume_drivers: ty.Dict[str, volume.LibvirtBaseVolumeDriver] = {}
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self._disk_cachemode = None
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self.image_cache_manager = imagecache.ImageCacheManager()
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@ -465,20 +465,6 @@ class LibvirtDriver(driver.ComputeDriver):
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align=ns['daxregion']['align'])
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return vpmems_host
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def _get_volume_drivers(self):
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driver_registry = dict()
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for driver_str in libvirt_volume_drivers:
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driver_type, _sep, driver = driver_str.partition('=')
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driver_class = importutils.import_class(driver)
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try:
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driver_registry[driver_type] = driver_class(self._host)
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except brick_exception.InvalidConnectorProtocol:
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LOG.debug('Unable to load volume driver %s. It is not '
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'supported on this host.', driver)
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return driver_registry
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@property
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def disk_cachemode(self):
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# It can be confusing to understand the QEMU cache mode
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@ -1580,11 +1566,55 @@ class LibvirtDriver(driver.ComputeDriver):
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except exception.InternalError as e:
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LOG.debug(e, instance=instance)
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def _get_volume_driver(self, connection_info):
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def _get_volume_driver(
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self, connection_info: ty.Dict[str, ty.Any]
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) -> 'volume.LibvirtBaseVolumeDriver':
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"""Fetch the nova.virt.libvirt.volume driver
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Based on the provided connection_info return a nova.virt.libvirt.volume
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driver. This will call out to os-brick to construct an connector and
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check if the connector is valid on the underlying host.
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:param connection_info: The connection_info associated with the volume
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:raises: VolumeDriverNotFound if no driver is found or if the host
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doesn't support the requested driver. This retains legacy behaviour
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when only supported drivers were loaded on startup leading to a
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VolumeDriverNotFound being raised later if an invalid driver was
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requested.
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"""
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driver_type = connection_info.get('driver_volume_type')
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if driver_type not in self.volume_drivers:
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# If the driver_type isn't listed in the supported type list fail
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if driver_type not in VOLUME_DRIVERS:
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raise exception.VolumeDriverNotFound(driver_type=driver_type)
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return self.volume_drivers[driver_type]
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# Return the cached driver
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if driver_type in self.volume_drivers:
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return self.volume_drivers.get(driver_type)
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@utils.synchronized('cache_volume_driver')
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def _cache_volume_driver(driver_type):
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# Check if another request cached the driver while we waited
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if driver_type in self.volume_drivers:
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return self.volume_drivers.get(driver_type)
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try:
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driver_class = importutils.import_class(
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VOLUME_DRIVERS.get(driver_type))
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self.volume_drivers[driver_type] = driver_class(self._host)
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return self.volume_drivers.get(driver_type)
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except brick_exception.InvalidConnectorProtocol:
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LOG.debug('Unable to load volume driver %s. It is not '
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'supported on this host.', driver_type)
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# NOTE(lyarwood): This exception is a subclass of
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# VolumeDriverNotFound to ensure no callers have to change
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# their error handling code after the move to on-demand loading
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# of the volume drivers and associated os-brick connectors.
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raise exception.VolumeDriverNotSupported(
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volume_driver=VOLUME_DRIVERS.get(driver_type))
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# Cache the volume driver if it hasn't already been
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return _cache_volume_driver(driver_type)
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def _connect_volume(self, context, connection_info, instance,
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encryption=None):
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