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Diffstat (limited to 'ceilometer/openstack/common/processutils.py')
| -rw-r--r-- | ceilometer/openstack/common/processutils.py | 285 |
1 files changed, 285 insertions, 0 deletions
diff --git a/ceilometer/openstack/common/processutils.py b/ceilometer/openstack/common/processutils.py new file mode 100644 index 00000000..ebb3cb74 --- /dev/null +++ b/ceilometer/openstack/common/processutils.py @@ -0,0 +1,285 @@ +# 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 errno +import logging +import multiprocessing +import os +import random +import shlex +import signal + +from eventlet.green import subprocess +from eventlet import greenthread +import six + +from ceilometer.openstack.common.gettextutils import _ +from ceilometer.openstack.common import strutils + + +LOG = logging.getLogger(__name__) + + +class InvalidArgumentError(Exception): + def __init__(self, message=None): + super(InvalidArgumentError, self).__init__(message) + + +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): + 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 = _('%(description)s\n' + 'Command: %(cmd)s\n' + 'Exit code: %(exit_code)s\n' + 'Stdout: %(stdout)r\n' + 'Stderr: %(stderr)r') % {'description': description, + 'cmd': cmd, + 'exit_code': exit_code, + 'stdout': stdout, + 'stderr': stderr} + super(ProcessExecutionError, self).__init__(message) + + +class NoRootWrapSpecified(Exception): + 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 env_variables: Environment variables and their values that + will be set for the process. + :type env_variables: dict + :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 logging.DEBUG or 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) + env_variables = kwargs.pop('env_variables', 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', 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: %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) + sanitized_cmd = strutils.mask_password(' '.join(cmd)) + + while attempts > 0: + attempts -= 1 + try: + LOG.log(loglevel, _('Running cmd (subprocess): %s'), sanitized_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, + env=env_variables) + result = None + for _i in six.moves.range(20): + # NOTE(russellb) 20 is an arbitrary number of retries to + # prevent any chance of looping forever here. + try: + if process_input is not None: + result = obj.communicate(process_input) + else: + result = obj.communicate() + except OSError as e: + if e.errno in (errno.EAGAIN, errno.EINTR): + continue + raise + break + 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 + sanitized_stdout = strutils.mask_password(stdout) + sanitized_stderr = strutils.mask_password(stderr) + raise ProcessExecutionError(exit_code=_returncode, + stdout=sanitized_stdout, + stderr=sanitized_stderr, + cmd=sanitized_cmd) + return result + except ProcessExecutionError: + if not attempts: + raise + else: + LOG.log(loglevel, _('%r failed. Retrying.'), sanitized_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 = '', six.text_type(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) + + +def get_worker_count(): + """Utility to get the default worker count. + + @return: The number of CPUs if that can be determined, else a default + worker count of 1 is returned. + """ + try: + return multiprocessing.cpu_count() + except NotImplementedError: + return 1 |