252 lines
9.0 KiB
Python
252 lines
9.0 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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# Copyright (c) 2013-2014 Wind River Systems, Inc.
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#
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"""
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System-level utilities and helper functions.
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"""
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import os
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import random
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import shlex
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import signal
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from eventlet.green import subprocess
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from eventlet import greenthread
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from sm_api.openstack.common.gettextutils import _
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from sm_api.openstack.common import log as logging
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LOG = logging.getLogger(__name__)
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class InvalidArgumentError(Exception):
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def __init__(self, message=None):
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super(InvalidArgumentError, self).__init__(message)
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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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self.exit_code = exit_code
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self.stderr = stderr
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self.stdout = stdout
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self.cmd = cmd
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self.description = description
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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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class NoRootWrapSpecified(Exception):
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def __init__(self, message=None):
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super(NoRootWrapSpecified, self).__init__(message)
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def _subprocess_setup():
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# Python installs a SIGPIPE handler by default. This is usually not what
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# non-Python subprocesses expect.
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signal.signal(signal.SIGPIPE, signal.SIG_DFL)
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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: Single bool, int, or list of allowed exit
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codes. Defaults to [0]. Raise
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:class:`ProcessExecutionError` unless
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program exits with one of these code.
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:type check_exit_code: boolean, int, or [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 to commands called with
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run_as_root=True
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:type root_helper: string
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:param shell: whether or not there should be a shell used to
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execute this command. Defaults to false.
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:type shell: boolean
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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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ignore_exit_code = False
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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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shell = kwargs.pop('shell', False)
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if isinstance(check_exit_code, bool):
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ignore_exit_code = not check_exit_code
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check_exit_code = [0]
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elif isinstance(check_exit_code, int):
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check_exit_code = [check_exit_code]
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if 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 and os.geteuid() != 0:
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if not root_helper:
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raise NoRootWrapSpecified(
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message=('Command requested root, but did not specify a root '
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'helper.'))
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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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if os.name == 'nt':
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preexec_fn = None
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close_fds = False
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else:
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preexec_fn = _subprocess_setup
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close_fds = True
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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=close_fds,
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preexec_fn=preexec_fn,
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shell=shell)
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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 not ignore_exit_code and _returncode not in 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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def trycmd(*args, **kwargs):
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"""
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A wrapper around execute() to more easily handle warnings and errors.
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Returns an (out, err) tuple of strings containing the output of
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the command's stdout and stderr. If 'err' is not empty then the
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command can be considered to have failed.
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:discard_warnings True | False. Defaults to False. If set to True,
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then for succeeding commands, stderr is cleared
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"""
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discard_warnings = kwargs.pop('discard_warnings', False)
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try:
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out, err = execute(*args, **kwargs)
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failed = False
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except ProcessExecutionError, exn:
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out, err = '', str(exn)
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failed = True
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if not failed and discard_warnings and err:
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# Handle commands that output to stderr but otherwise succeed
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err = ''
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return out, err
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def ssh_execute(ssh, cmd, process_input=None,
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addl_env=None, check_exit_code=True):
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LOG.debug(_('Running cmd (SSH): %s'), cmd)
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if addl_env:
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raise InvalidArgumentError(_('Environment not supported over SSH'))
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if process_input:
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# This is (probably) fixable if we need it...
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raise InvalidArgumentError(_('process_input not supported over SSH'))
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stdin_stream, stdout_stream, stderr_stream = ssh.exec_command(cmd)
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channel = stdout_stream.channel
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# NOTE(justinsb): This seems suspicious...
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# ...other SSH clients have buffering issues with this approach
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stdout = stdout_stream.read()
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stderr = stderr_stream.read()
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stdin_stream.close()
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exit_status = channel.recv_exit_status()
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# exit_status == -1 if no exit code was returned
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if exit_status != -1:
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LOG.debug(_('Result was %s') % exit_status)
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if check_exit_code and exit_status != 0:
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raise ProcessExecutionError(exit_code=exit_status,
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stdout=stdout,
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stderr=stderr,
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cmd=cmd)
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return (stdout, stderr)
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