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# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright 2011 OpenStack LLC.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""
System-level utilities and helper functions.
"""
import logging
import random
import shlex
from eventlet.green import subprocess
from eventlet import greenthread
from openstack.common.gettextutils import _
LOG = logging.getLogger(__name__)
class UnknownArgumentError(Exception):
def __init__(self, message=None):
super(UnknownArgumentError, self).__init__(message)
class ProcessExecutionError(Exception):
def __init__(self, stdout=None, stderr=None, exit_code=None, cmd=None,
description=None):
if description is None:
description = "Unexpected error while running command."
if exit_code is None:
exit_code = '-'
message = ("%s\nCommand: %s\nExit code: %s\nStdout: %r\nStderr: %r"
% (description, cmd, exit_code, stdout, stderr))
super(ProcessExecutionError, self).__init__(message)
def execute(*cmd, **kwargs):
"""
Helper method to shell out and execute a command through subprocess with
optional retry.
:param cmd: Passed to subprocess.Popen.
:type cmd: string
:param process_input: Send to opened process.
:type proces_input: string
:param check_exit_code: Defaults to 0. Will raise
:class:`ProcessExecutionError`
if the command exits without returning this value
as a returncode
:type check_exit_code: int
:param delay_on_retry: True | False. Defaults to True. If set to True,
wait a short amount of time before retrying.
:type delay_on_retry: boolean
:param attempts: How many times to retry cmd.
:type attempts: int
:param run_as_root: True | False. Defaults to False. If set to True,
the command is prefixed by the command specified
in the root_helper kwarg.
:type run_as_root: boolean
:param root_helper: command to prefix all cmd's with
:type root_helper: string
:returns: (stdout, stderr) from process execution
:raises: :class:`UnknownArgumentError` on
receiving unknown arguments
:raises: :class:`ProcessExecutionError`
"""
process_input = kwargs.pop('process_input', None)
check_exit_code = kwargs.pop('check_exit_code', 0)
delay_on_retry = kwargs.pop('delay_on_retry', True)
attempts = kwargs.pop('attempts', 1)
run_as_root = kwargs.pop('run_as_root', False)
root_helper = kwargs.pop('root_helper', '')
if len(kwargs):
raise UnknownArgumentError(_('Got unknown keyword args '
'to utils.execute: %r') % kwargs)
if run_as_root:
cmd = shlex.split(root_helper) + list(cmd)
cmd = map(str, cmd)
while attempts > 0:
attempts -= 1
try:
LOG.debug(_('Running cmd (subprocess): %s'), ' '.join(cmd))
_PIPE = subprocess.PIPE # pylint: disable=E1101
obj = subprocess.Popen(cmd,
stdin=_PIPE,
stdout=_PIPE,
stderr=_PIPE,
close_fds=True)
result = None
if process_input is not None:
result = obj.communicate(process_input)
else:
result = obj.communicate()
obj.stdin.close() # pylint: disable=E1101
_returncode = obj.returncode # pylint: disable=E1101
if _returncode:
LOG.debug(_('Result was %s') % _returncode)
if (isinstance(check_exit_code, int) and
not isinstance(check_exit_code, bool) and
_returncode != check_exit_code):
(stdout, stderr) = result
raise ProcessExecutionError(exit_code=_returncode,
stdout=stdout,
stderr=stderr,
cmd=' '.join(cmd))
return result
except ProcessExecutionError:
if not attempts:
raise
else:
LOG.debug(_('%r failed. Retrying.'), cmd)
if delay_on_retry:
greenthread.sleep(random.randint(20, 200) / 100.0)
finally:
# NOTE(termie): this appears to be necessary to let the subprocess
# call clean something up in between calls, without
# it two execute calls in a row hangs the second one
greenthread.sleep(0)
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