80 lines
3.5 KiB
Python
80 lines
3.5 KiB
Python
# Copyright 2015 Red Hat, Inc.
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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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from oslo_concurrency import processutils as putils
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from oslo_log import log as logging
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from oslo_utils import encodeutils
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from oslo_utils import units
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from taskflow import task
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from glance.i18n import _LW
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LOG = logging.getLogger(__name__)
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# NOTE(hemanthm): As reported in the bug #1449062, "qemu-img info" calls can
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# be exploited to craft DoS attacks by providing malicious input. The process
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# limits defined here are protections against such attacks. This essentially
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# limits the CPU time and address space used by the process that executes
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# "qemu-img info" command to 2 seconds and 1 GB respectively.
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QEMU_IMG_PROC_LIMITS = putils.ProcessLimits(cpu_time=2,
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address_space=1 * units.Gi)
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class OptionalTask(task.Task):
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def __init__(self, *args, **kwargs):
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super(OptionalTask, self).__init__(*args, **kwargs)
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self.execute = self._catch_all(self.execute)
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def _catch_all(self, func):
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# NOTE(flaper87): Read this comment before calling the MI6
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# Here's the thing, there's no nice way to define "optional"
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# tasks. That is, tasks whose failure shouldn't affect the execution
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# of the flow. The only current "sane" way to do this, is by catching
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# everything and logging. This seems harmless from a taskflow
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# perspective but it is not. There are some issues related to this
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# "workaround":
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#
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# - Task's states will shamelessly lie to us saying the task succeeded.
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#
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# - No revert procedure will be triggered, which means optional tasks,
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# for now, mustn't cause any side-effects because they won't be able to
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# clean them up. If these tasks depend on other task that do cause side
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# effects, a task that cleans those side effects most be registered as
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# well. For example, _ImportToFS, _MyDumbTask, _DeleteFromFS.
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#
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# - Ideally, optional tasks shouldn't `provide` new values unless they
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# are part of an optional flow. Due to the decoration of the execute
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# method, these tasks will need to define the provided methods at
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# class level using `default_provides`.
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#
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#
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# The taskflow team is working on improving this and on something that
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# will provide the ability of defining optional tasks. For now, to lie
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# ourselves we must.
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#
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# NOTE(harlowja): The upstream change that is hopefully going to make
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# this easier/built-in is at: https://review.openstack.org/#/c/271116/
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def wrapper(*args, **kwargs):
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try:
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return func(*args, **kwargs)
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except Exception as exc:
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msg = (_LW("An optional task has failed, "
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"the failure was: %s") %
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encodeutils.exception_to_unicode(exc))
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LOG.warn(msg)
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return wrapper
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