136 lines
5.4 KiB
Python
136 lines
5.4 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright 2011 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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"""
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System-level utilities and helper functions.
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"""
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import logging
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import random
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import shlex
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from eventlet.green import subprocess
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from eventlet import greenthread
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from quantum.openstack.common.gettextutils import _
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LOG = logging.getLogger(__name__)
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class UnknownArgumentError(Exception):
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def __init__(self, message=None):
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super(UnknownArgumentError, self).__init__(message)
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class ProcessExecutionError(Exception):
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def __init__(self, stdout=None, stderr=None, exit_code=None, cmd=None,
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description=None):
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if description is None:
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description = "Unexpected error while running command."
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if exit_code is None:
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exit_code = '-'
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message = ("%s\nCommand: %s\nExit code: %s\nStdout: %r\nStderr: %r"
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% (description, cmd, exit_code, stdout, stderr))
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super(ProcessExecutionError, self).__init__(message)
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def execute(*cmd, **kwargs):
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"""
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Helper method to shell out and execute a command through subprocess with
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optional retry.
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:param cmd: Passed to subprocess.Popen.
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:type cmd: string
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:param process_input: Send to opened process.
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:type proces_input: string
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:param check_exit_code: Defaults to 0. Will raise
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:class:`ProcessExecutionError`
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if the command exits without returning this value
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as a returncode
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:type check_exit_code: int
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:param delay_on_retry: True | False. Defaults to True. If set to True,
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wait a short amount of time before retrying.
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:type delay_on_retry: boolean
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:param attempts: How many times to retry cmd.
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:type attempts: int
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:param run_as_root: True | False. Defaults to False. If set to True,
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the command is prefixed by the command specified
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in the root_helper kwarg.
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:type run_as_root: boolean
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:param root_helper: command to prefix all cmd's with
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:type root_helper: string
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:returns: (stdout, stderr) from process execution
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:raises: :class:`UnknownArgumentError` on
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receiving unknown arguments
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:raises: :class:`ProcessExecutionError`
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"""
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process_input = kwargs.pop('process_input', None)
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check_exit_code = kwargs.pop('check_exit_code', 0)
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delay_on_retry = kwargs.pop('delay_on_retry', True)
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attempts = kwargs.pop('attempts', 1)
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run_as_root = kwargs.pop('run_as_root', False)
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root_helper = kwargs.pop('root_helper', '')
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if len(kwargs):
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raise UnknownArgumentError(_('Got unknown keyword args '
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'to utils.execute: %r') % kwargs)
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if run_as_root:
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cmd = shlex.split(root_helper) + list(cmd)
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cmd = map(str, cmd)
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while attempts > 0:
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attempts -= 1
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try:
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LOG.debug(_('Running cmd (subprocess): %s'), ' '.join(cmd))
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_PIPE = subprocess.PIPE # pylint: disable=E1101
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obj = subprocess.Popen(cmd,
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stdin=_PIPE,
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stdout=_PIPE,
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stderr=_PIPE,
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close_fds=True)
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result = None
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if process_input is not None:
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result = obj.communicate(process_input)
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else:
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result = obj.communicate()
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obj.stdin.close() # pylint: disable=E1101
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_returncode = obj.returncode # pylint: disable=E1101
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if _returncode:
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LOG.debug(_('Result was %s') % _returncode)
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if (isinstance(check_exit_code, int) and
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not isinstance(check_exit_code, bool) and
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_returncode != check_exit_code):
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(stdout, stderr) = result
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raise ProcessExecutionError(exit_code=_returncode,
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stdout=stdout,
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stderr=stderr,
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cmd=' '.join(cmd))
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return result
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except ProcessExecutionError:
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if not attempts:
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raise
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else:
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LOG.debug(_('%r failed. Retrying.'), cmd)
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if delay_on_retry:
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greenthread.sleep(random.randint(20, 200) / 100.0)
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finally:
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# NOTE(termie): this appears to be necessary to let the subprocess
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# call clean something up in between calls, without
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# it two execute calls in a row hangs the second one
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greenthread.sleep(0)
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