Merge "Add a workaround config toggle to refuse ceph image upload"
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Zuul
Gerrit Code Review
commit
b0cae0750c
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@ -246,6 +246,30 @@ candidates if necessary. This has a slight performance impact and is not
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necessary on new or upgraded deployments where the new configuration has been
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set on all hosts. By setting this option, the second lookup is disabled and the
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scheduler will only request ``PCPU``-based allocations.
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"""),
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cfg.BoolOpt(
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'never_download_image_if_on_rbd',
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default=False,
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help="""
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When booting from an image on a ceph-backed compute node, if the image does not
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already reside on the ceph cluster (as would be the case if glance is
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also using the same cluster), nova will download the image from glance and
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upload it to ceph itself. If using multiple ceph clusters, this may cause nova
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to unintentionally duplicate the image in a non-COW-able way in the local
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ceph deployment, wasting space.
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For more information, refer to the bug report:
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https://bugs.launchpad.net/nova/+bug/1858877
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Enabling this option will cause nova to *refuse* to boot an instance if it
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would require downloading the image from glance and uploading it to ceph
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itself.
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Related options:
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* ``compute_driver`` (libvirt)
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* ``[libvirt]/images_type`` (rbd)
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"""),
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]
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@ -21454,6 +21454,52 @@ class LibvirtDriverTestCase(test.NoDBTestCase, TraitsComparisonMixin):
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None)
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self.assertFalse(mock_inject.called)
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@mock.patch('nova.virt.libvirt.utils.fetch_image')
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@mock.patch('nova.virt.libvirt.storage.rbd_utils.RBDDriver')
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@mock.patch.object(imagebackend, 'IMAGE_API')
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def test_create_fetch_image_ceph_workaround(self, mock_image, mock_rbd,
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mock_fetch):
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# Make sure that rbd clone will fail as un-clone-able
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mock_rbd.is_cloneable.return_value = False
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# Make sure the rbd code thinks the image does not already exist
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mock_rbd.return_value.exists.return_value = False
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# Make sure the rbd code says the image is small
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mock_rbd.return_value.size.return_value = 128 * units.Mi
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# Make sure IMAGE_API.get() returns a raw image
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mock_image.get.return_value = {'locations': [], 'disk_format': 'raw'}
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instance = self._create_instance()
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disk_images = {'image_id': 'foo'}
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self.flags(images_type='rbd', group='libvirt')
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drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
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def do_create():
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# Reset the fetch mock and run our driver method so we can
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# check for called-ness after each attempt
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mock_fetch.reset_mock()
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drvr._create_and_inject_local_root(self.context,
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instance,
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False,
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'',
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disk_images,
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get_injection_info(),
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None)
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# Do an image create with rbd
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do_create()
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# Make sure it tried fetch, which implies that it tried and
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# failed to clone.
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mock_fetch.assert_called()
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# Enable the workaround
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self.flags(never_download_image_if_on_rbd=True,
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group='workarounds')
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# Ensure that we raise the original ImageUnacceptable from the
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# failed clone...
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self.assertRaises(exception.ImageUnacceptable, do_create)
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# ...and ensure that we did _not_ try to fetch
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mock_fetch.assert_not_called()
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@mock.patch('nova.virt.netutils.get_injected_network_template')
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@mock.patch('nova.virt.disk.api.inject_data')
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@mock.patch.object(libvirt_driver.LibvirtDriver, "_conn")
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@ -3867,9 +3867,24 @@ class LibvirtDriver(driver.ComputeDriver):
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backend.create_snap(libvirt_utils.RESIZE_SNAPSHOT_NAME)
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if backend.SUPPORTS_CLONE:
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def clone_fallback_to_fetch(*args, **kwargs):
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refuse_fetch = (
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CONF.libvirt.images_type == 'rbd' and
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CONF.workarounds.never_download_image_if_on_rbd)
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try:
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backend.clone(context, disk_images['image_id'])
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except exception.ImageUnacceptable:
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if refuse_fetch:
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# Re-raise the exception from the failed
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# ceph clone. The compute manager expects
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# ImageUnacceptable as a possible result
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# of spawn(), from which this is called.
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with excutils.save_and_reraise_exception():
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LOG.warning(
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'Image %s is not on my ceph and '
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'[workarounds]/'
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'never_download_image_if_on_rbd=True;'
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' refusing to fetch and upload.',
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disk_images['image_id'])
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libvirt_utils.fetch_image(*args, **kwargs)
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fetch_func = clone_fallback_to_fetch
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else:
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@ -0,0 +1,19 @@
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---
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other:
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- |
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Nova now has a config option called
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``[workarounds]/never_download_image_if_on_rbd`` which helps to
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avoid pathological storage behavior with multiple ceph clusters.
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Currently, Nova does *not* support multiple ceph clusters
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properly, but Glance can be configured with them. If an instance
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is booted from an image residing in a ceph cluster other than the
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one Nova knows about, it will silently download it from Glance and
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re-upload the image to the local ceph privately for that
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instance. Unlike the behavior you expect when configuring Nova and
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Glance for ceph, Nova will continue to do this over and over for
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the same image when subsequent instances are booted, consuming a
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large amount of storage unexpectedly. The new workaround option
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will cause Nova to refuse to do this download/upload behavior and
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instead fail the instance boot. It is simply a stop-gap effort to
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allow unsupported deployments with multiple ceph clusters from
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silently consuming large amounts of disk space.
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