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OpenStack Study: processutils.py**** CubicPower OpenStack Study ****
# Copyright 2011 OpenStack Foundation. # 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 as stdlib_logging import os import random import shlex import signal from eventlet.green import subprocess from eventlet import greenthread from neutron.openstack.common.gettextutils import _ from neutron.openstack.common import log as logging LOG = logging.getLogger(__name__)
**** CubicPower OpenStack Study **** class InvalidArgumentError(Exception):
**** CubicPower OpenStack Study **** def __init__(self, message=None): super(InvalidArgumentError, self).__init__(message)
**** CubicPower OpenStack Study **** class UnknownArgumentError(Exception):
**** CubicPower OpenStack Study **** def __init__(self, message=None): super(UnknownArgumentError, self).__init__(message)
**** CubicPower OpenStack Study **** class ProcessExecutionError(Exception):
**** CubicPower OpenStack Study **** def __init__(self, stdout=None, stderr=None, exit_code=None, cmd=None, description=None): self.exit_code = exit_code self.stderr = stderr self.stdout = stdout self.cmd = cmd self.description = description 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)
**** CubicPower OpenStack Study **** class NoRootWrapSpecified(Exception):
**** CubicPower OpenStack Study **** def __init__(self, message=None): super(NoRootWrapSpecified, self).__init__(message) def _subprocess_setup(): # Python installs a SIGPIPE handler by default. This is usually not what # non-Python subprocesses expect. signal.signal(signal.SIGPIPE, signal.SIG_DFL) def execute(*cmd, **kwargs): """Helper method to shell out and execute a command through subprocess. Allows optional retry. :param cmd: Passed to subprocess.Popen. :type cmd: string :param process_input: Send to opened process. :type process_input: string :param check_exit_code: Single bool, int, or list of allowed exit codes. Defaults to [0]. Raise :class:`ProcessExecutionError` unless program exits with one of these code. :type check_exit_code: boolean, int, or [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 to commands called with run_as_root=True :type root_helper: string :param shell: whether or not there should be a shell used to execute this command. Defaults to false. :type shell: boolean :param loglevel: log level for execute commands. :type loglevel: int. (Should be stdlib_logging.DEBUG or stdlib_logging.INFO) :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]) ignore_exit_code = False 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', '') shell = kwargs.pop('shell', False) loglevel = kwargs.pop('loglevel', stdlib_logging.DEBUG) if isinstance(check_exit_code, bool): ignore_exit_code = not check_exit_code check_exit_code = [0] elif isinstance(check_exit_code, int): check_exit_code = [check_exit_code] if kwargs: raise UnknownArgumentError(_('Got unknown keyword args ' 'to utils.execute: %r') % kwargs) if run_as_root and hasattr(os, 'geteuid') and os.geteuid() != 0: if not root_helper: raise NoRootWrapSpecified( message=('Command requested root, but did not specify a root ' 'helper.')) cmd = shlex.split(root_helper) + list(cmd) cmd = map(str, cmd) while attempts > 0: attempts -= 1 try: LOG.log(loglevel, _('Running cmd (subprocess): %s'), ' '.join(cmd)) _PIPE = subprocess.PIPE # pylint: disable=E1101 if os.name == 'nt': preexec_fn = None close_fds = False else: preexec_fn = _subprocess_setup close_fds = True obj = subprocess.Popen(cmd, stdin=_PIPE, stdout=_PIPE, stderr=_PIPE, close_fds=close_fds, preexec_fn=preexec_fn, shell=shell) 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 LOG.log(loglevel, _('Result was %s') % _returncode) if not ignore_exit_code and _returncode not in 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.log(loglevel, _('%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) def trycmd(*args, **kwargs): """A wrapper around execute() to more easily handle warnings and errors. Returns an (out, err) tuple of strings containing the output of the command's stdout and stderr. If 'err' is not empty then the command can be considered to have failed. :discard_warnings True | False. Defaults to False. If set to True, then for succeeding commands, stderr is cleared """ discard_warnings = kwargs.pop('discard_warnings', False) try: out, err = execute(*args, **kwargs) failed = False except ProcessExecutionError as exn: out, err = '', str(exn) failed = True if not failed and discard_warnings and err: # Handle commands that output to stderr but otherwise succeed err = '' return out, err def ssh_execute(ssh, cmd, process_input=None, addl_env=None, check_exit_code=True): LOG.debug(_('Running cmd (SSH): %s'), cmd) if addl_env: raise InvalidArgumentError(_('Environment not supported over SSH')) if process_input: # This is (probably) fixable if we need it... raise InvalidArgumentError(_('process_input not supported over SSH')) stdin_stream, stdout_stream, stderr_stream = ssh.exec_command(cmd) channel = stdout_stream.channel # NOTE(justinsb): This seems suspicious... # ...other SSH clients have buffering issues with this approach stdout = stdout_stream.read() stderr = stderr_stream.read() stdin_stream.close() exit_status = channel.recv_exit_status() # exit_status == -1 if no exit code was returned if exit_status != -1: LOG.debug(_('Result was %s') % exit_status) if check_exit_code and exit_status != 0: raise ProcessExecutionError(exit_code=exit_status, stdout=stdout, stderr=stderr, cmd=cmd) return (stdout, stderr)
**** CubicPower OpenStack Study **** def _subprocess_setup(): # Python installs a SIGPIPE handler by default. This is usually not what # non-Python subprocesses expect. signal.signal(signal.SIGPIPE, signal.SIG_DFL)
**** CubicPower OpenStack Study **** def execute(*cmd, **kwargs): """Helper method to shell out and execute a command through subprocess. Allows optional retry. :param cmd: Passed to subprocess.Popen. :type cmd: string :param process_input: Send to opened process. :type process_input: string :param check_exit_code: Single bool, int, or list of allowed exit codes. Defaults to [0]. Raise :class:`ProcessExecutionError` unless program exits with one of these code. :type check_exit_code: boolean, int, or [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 to commands called with run_as_root=True :type root_helper: string :param shell: whether or not there should be a shell used to execute this command. Defaults to false. :type shell: boolean :param loglevel: log level for execute commands. :type loglevel: int. (Should be stdlib_logging.DEBUG or stdlib_logging.INFO) :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]) ignore_exit_code = False 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', '') shell = kwargs.pop('shell', False) loglevel = kwargs.pop('loglevel', stdlib_logging.DEBUG) if isinstance(check_exit_code, bool): ignore_exit_code = not check_exit_code check_exit_code = [0] elif isinstance(check_exit_code, int): check_exit_code = [check_exit_code] if kwargs: raise UnknownArgumentError(_('Got unknown keyword args ' 'to utils.execute: %r') % kwargs) if run_as_root and hasattr(os, 'geteuid') and os.geteuid() != 0: if not root_helper: raise NoRootWrapSpecified( message=('Command requested root, but did not specify a root ' 'helper.')) cmd = shlex.split(root_helper) + list(cmd) cmd = map(str, cmd) while attempts > 0: attempts -= 1 try: LOG.log(loglevel, _('Running cmd (subprocess): %s'), ' '.join(cmd)) _PIPE = subprocess.PIPE # pylint: disable=E1101 if os.name == 'nt': preexec_fn = None close_fds = False else: preexec_fn = _subprocess_setup close_fds = True obj = subprocess.Popen(cmd, stdin=_PIPE, stdout=_PIPE, stderr=_PIPE, close_fds=close_fds, preexec_fn=preexec_fn, shell=shell) 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 LOG.log(loglevel, _('Result was %s') % _returncode) if not ignore_exit_code and _returncode not in 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.log(loglevel, _('%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)
**** CubicPower OpenStack Study **** def trycmd(*args, **kwargs): """A wrapper around execute() to more easily handle warnings and errors. Returns an (out, err) tuple of strings containing the output of the command's stdout and stderr. If 'err' is not empty then the command can be considered to have failed. :discard_warnings True | False. Defaults to False. If set to True, then for succeeding commands, stderr is cleared """ discard_warnings = kwargs.pop('discard_warnings', False) try: out, err = execute(*args, **kwargs) failed = False except ProcessExecutionError as exn: out, err = '', str(exn) failed = True if not failed and discard_warnings and err: # Handle commands that output to stderr but otherwise succeed err = '' return out, err
**** CubicPower OpenStack Study **** def ssh_execute(ssh, cmd, process_input=None, addl_env=None, check_exit_code=True): LOG.debug(_('Running cmd (SSH): %s'), cmd) if addl_env: raise InvalidArgumentError(_('Environment not supported over SSH')) if process_input: # This is (probably) fixable if we need it... raise InvalidArgumentError(_('process_input not supported over SSH')) stdin_stream, stdout_stream, stderr_stream = ssh.exec_command(cmd) channel = stdout_stream.channel # NOTE(justinsb): This seems suspicious... # ...other SSH clients have buffering issues with this approach stdout = stdout_stream.read() stderr = stderr_stream.read() stdin_stream.close() exit_status = channel.recv_exit_status() # exit_status == -1 if no exit code was returned if exit_status != -1: LOG.debug(_('Result was %s') % exit_status) if check_exit_code and exit_status != 0: raise ProcessExecutionError(exit_code=exit_status, stdout=stdout, stderr=stderr, cmd=cmd) return (stdout, stderr)
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