137 lines
4.5 KiB
Python
137 lines
4.5 KiB
Python
# Copyright 2016 OpenStack Foundation
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""The 'workarounds' group is for very specific reasons.
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If you're:
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- Working around an issue in a system tool (e.g. libvirt or qemu) where the
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fix is in flight/discussed in that community.
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- The tool can be/is fixed in some distributions and rather than patch the
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code those distributions can trivially set a config option to get the
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"correct" behavior.
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Then this is a good place for your workaround.
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.. warning::
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Please use with care! Document the BugID that your workaround is paired with.
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"""
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from oslo_config import cfg
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workarounds_group = cfg.OptGroup(
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'workarounds',
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title='Workaround Options',
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help="""
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A collection of workarounds used to mitigate bugs or issues found in system
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tools (e.g. Libvirt or QEMU) or Nova itself under certain conditions. These
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should only be enabled in exceptional circumstances. All options are linked
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against bug IDs, where more information on the issue can be found.
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""")
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ALL_OPTS = [
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cfg.BoolOpt(
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'disable_rootwrap',
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default=False,
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help="""
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Use sudo instead of rootwrap.
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Allow fallback to sudo for performance reasons.
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For more information, refer to the bug report:
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https://bugs.launchpad.net/nova/+bug/1415106
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Possible values:
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* True: Use sudo instead of rootwrap
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* False: Use rootwrap as usual
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Interdependencies to other options:
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* Any options that affect 'rootwrap' will be ignored.
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"""),
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cfg.BoolOpt(
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'disable_libvirt_livesnapshot',
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default=True,
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help="""
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Disable live snapshots when using the libvirt driver.
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Live snapshots allow the snapshot of the disk to happen without an
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interruption to the guest, using coordination with a guest agent to
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quiesce the filesystem.
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When using libvirt 1.2.2 live snapshots fail intermittently under load
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(likely related to concurrent libvirt/qemu operations). This config
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option provides a mechanism to disable live snapshot, in favor of cold
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snapshot, while this is resolved. Cold snapshot causes an instance
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outage while the guest is going through the snapshotting process.
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For more information, refer to the bug report:
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https://bugs.launchpad.net/nova/+bug/1334398
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Possible values:
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* True: Live snapshot is disabled when using libvirt
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* False: Live snapshots are always used when snapshotting (as long as
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there is a new enough libvirt and the backend storage supports it)
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"""),
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cfg.BoolOpt(
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'handle_virt_lifecycle_events',
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default=True,
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help="""
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Enable handling of events emitted from compute drivers.
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Many compute drivers emit lifecycle events, which are events that occur when,
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for example, an instance is starting or stopping. If the instance is going
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through task state changes due to an API operation, like resize, the events
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are ignored.
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This is an advanced feature which allows the hypervisor to signal to the
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compute service that an unexpected state change has occurred in an instance
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and that the instance can be shutdown automatically. Unfortunately, this can
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race in some conditions, for example in reboot operations or when the compute
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service or when host is rebooted (planned or due to an outage). If such races
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are common, then it is advisable to disable this feature.
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Care should be taken when this feature is disabled and
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'sync_power_state_interval' is set to a negative value. In this case, any
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instances that get out of sync between the hypervisor and the Nova database
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will have to be synchronized manually.
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For more information, refer to the bug report:
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https://bugs.launchpad.net/bugs/1444630
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Interdependencies to other options:
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* If ``sync_power_state_interval`` is negative and this feature is disabled,
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then instances that get out of sync between the hypervisor and the Nova
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database will have to be synchronized manually.
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"""),
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]
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def register_opts(conf):
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conf.register_group(workarounds_group)
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conf.register_opts(ALL_OPTS, group=workarounds_group)
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def list_opts():
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return {workarounds_group: ALL_OPTS}
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