# 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 functools import logging import multiprocessing import os import random import shlex import signal import sys import time import enum from oslo_utils import encodeutils from oslo_utils import importutils from oslo_utils import strutils from oslo_utils import timeutils import six from oslo_concurrency._i18n import _ # NOTE(bnemec): eventlet doesn't monkey patch subprocess, so we need to # determine the proper subprocess module to use ourselves. I'm using the # time module as the check because that's a monkey patched module we use # in combination with subprocess below, so they need to match. eventlet = importutils.try_import('eventlet') eventlet_patched = eventlet and eventlet.patcher.is_monkey_patched(time) if eventlet_patched: if os.name == 'nt': # subprocess.Popen.communicate will spawn two threads consuming # stdout/stderr when passing data through stdin. We need to make # sure that *native* threads will be used as pipes are blocking # on Windows. # Recent eventlet versions actually do patch subprocess. subprocess = eventlet.patcher.original('subprocess') subprocess.threading = eventlet.patcher.original('threading') else: from eventlet.green import subprocess from eventlet import tpool else: import subprocess 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): super(ProcessExecutionError, self).__init__( stdout, stderr, exit_code, cmd, description) self.exit_code = exit_code self.stderr = stderr self.stdout = stdout self.cmd = cmd self.description = description def __str__(self): description = self.description if description is None: description = _("Unexpected error while running command.") exit_code = self.exit_code 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': self.cmd, 'exit_code': exit_code, 'stdout': self.stdout, 'stderr': self.stderr} return message class NoRootWrapSpecified(Exception): def __init__(self, message=None): super(NoRootWrapSpecified, self).__init__(message) def _subprocess_setup(on_preexec_fn): # Python installs a SIGPIPE handler by default. This is usually not what # non-Python subprocesses expect. signal.signal(signal.SIGPIPE, signal.SIG_DFL) if on_preexec_fn: on_preexec_fn() @enum.unique class LogErrors(enum.IntEnum): """Enumerations that affect if stdout and stderr are logged on error. .. versionadded:: 2.7 """ #: No logging on errors. DEFAULT = 0 #: Log an error on **each** occurence of an error. ALL = 1 #: Log an error on the last attempt that errored **only**. FINAL = 2 # Retain these aliases for a number of releases... LOG_ALL_ERRORS = LogErrors.ALL LOG_FINAL_ERROR = LogErrors.FINAL LOG_DEFAULT_ERROR = LogErrors.DEFAULT class ProcessLimits(object): """Resource limits on a process. Attributes: * address_space: Address space limit in bytes * core_file_size: Core file size limit in bytes * cpu_time: CPU time limit in seconds * data_size: Data size limit in bytes * file_size: File size limit in bytes * memory_locked: Locked memory limit in bytes * number_files: Maximum number of open files * number_processes: Maximum number of processes * resident_set_size: Maximum Resident Set Size (RSS) in bytes * stack_size: Stack size limit in bytes This object can be used for the *prlimit* parameter of :func:`execute`. """ _LIMITS = { "address_space": "--as", "core_file_size": "--core", "cpu_time": "--cpu", "data_size": "--data", "file_size": "--fsize", "memory_locked": "--memlock", "number_files": "--nofile", "number_processes": "--nproc", "resident_set_size": "--rss", "stack_size": "--stack", } def __init__(self, **kw): for limit in self._LIMITS: setattr(self, limit, kw.pop(limit, None)) if kw: raise ValueError("invalid limits: %s" % ', '.join(sorted(kw.keys()))) def prlimit_args(self): """Create a list of arguments for the prlimit command line.""" args = [] for limit in self._LIMITS: val = getattr(self, limit) if val is not None: args.append("%s=%s" % (self._LIMITS[limit], val)) return args 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 cwd: Set the current working directory :type cwd: string :param process_input: Send to opened process. :type process_input: string or bytes :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) :param log_errors: Should stdout and stderr be logged on error? Possible values are :py:attr:`~.LogErrors.DEFAULT`, :py:attr:`~.LogErrors.FINAL`, or :py:attr:`~.LogErrors.ALL`. Note that the values :py:attr:`~.LogErrors.FINAL` and :py:attr:`~.LogErrors.ALL` are **only** relevant when multiple attempts of command execution are requested using the ``attempts`` parameter. :type log_errors: :py:class:`~.LogErrors` :param binary: On Python 3, return stdout and stderr as bytes if binary is True, as Unicode otherwise. :type binary: boolean :param on_execute: This function will be called upon process creation with the object as a argument. The Purpose of this is to allow the caller of `processutils.execute` to track process creation asynchronously. :type on_execute: function(:class:`subprocess.Popen`) :param on_completion: This function will be called upon process completion with the object as a argument. The Purpose of this is to allow the caller of `processutils.execute` to track process completion asynchronously. :type on_completion: function(:class:`subprocess.Popen`) :param preexec_fn: This function will be called in the child process just before the child is executed. WARNING: On windows, we silently drop this preexec_fn as it is not supported by subprocess.Popen on windows (throws a ValueError) :type preexec_fn: function() :param prlimit: Set resource limits on the child process. See below for a detailed description. :type prlimit: :class:`ProcessLimits` :param python_exec: The python executable to use for enforcing prlimits. If this is not set it will default to use sys.executable. :type python_exec: string :returns: (stdout, stderr) from process execution :raises: :class:`UnknownArgumentError` on receiving unknown arguments :raises: :class:`ProcessExecutionError` :raises: :class:`OSError` The *prlimit* parameter can be used to set resource limits on the child process. If this parameter is used, the child process will be spawned by a wrapper process which will set limits before spawning the command. .. versionchanged:: 3.17 *process_input* can now be either bytes or string on python3. .. versionchanged:: 3.4 Added *prlimit* optional parameter. .. versionchanged:: 1.5 Added *cwd* optional parameter. .. versionchanged:: 1.9 Added *binary* optional parameter. On Python 3, *stdout* and *stderr* are now returned as Unicode strings by default, or bytes if *binary* is true. .. versionchanged:: 2.1 Added *on_execute* and *on_completion* optional parameters. .. versionchanged:: 2.3 Added *preexec_fn* optional parameter. """ cwd = kwargs.pop('cwd', None) process_input = kwargs.pop('process_input', None) if process_input is not None: process_input = encodeutils.to_utf8(process_input) 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) log_errors = kwargs.pop('log_errors', None) if log_errors is None: log_errors = LogErrors.DEFAULT binary = kwargs.pop('binary', False) on_execute = kwargs.pop('on_execute', None) on_completion = kwargs.pop('on_completion', None) preexec_fn = kwargs.pop('preexec_fn', None) prlimit = kwargs.pop('prlimit', None) python_exec = kwargs.pop('python_exec', sys.executable) 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 isinstance(log_errors, six.integer_types): log_errors = LogErrors(log_errors) if not isinstance(log_errors, LogErrors): raise InvalidArgumentError(_('Got invalid arg log_errors: %r') % log_errors) 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.')) if shell: # root helper has to be injected into the command string cmd = [' '.join((root_helper, cmd[0]))] + list(cmd[1:]) else: # root helper has to be tokenized into argument list cmd = shlex.split(root_helper) + list(cmd) cmd = [str(c) for c in cmd] if prlimit: if os.name == 'nt': LOG.log(loglevel, _('Process resource limits are ignored as ' 'this feature is not supported on Windows.')) else: args = [python_exec, '-m', 'oslo_concurrency.prlimit'] args.extend(prlimit.prlimit_args()) args.append('--') args.extend(cmd) cmd = args sanitized_cmd = strutils.mask_password(' '.join(cmd)) watch = timeutils.StopWatch() while attempts > 0: attempts -= 1 watch.restart() try: LOG.log(loglevel, _('Running cmd (subprocess): %s'), sanitized_cmd) _PIPE = subprocess.PIPE # pylint: disable=E1101 if os.name == 'nt': on_preexec_fn = None close_fds = False else: on_preexec_fn = functools.partial(_subprocess_setup, preexec_fn) close_fds = True obj = subprocess.Popen(cmd, stdin=_PIPE, stdout=_PIPE, stderr=_PIPE, close_fds=close_fds, preexec_fn=on_preexec_fn, shell=shell, # nosec:B604 cwd=cwd, env=env_variables) if on_execute: on_execute(obj) try: # eventlet.green.subprocess is not really greenthread friendly # on Windows. In order to avoid blocking other greenthreads, # we have to wrap this call using tpool. if eventlet_patched and os.name == 'nt': result = tpool.execute(obj.communicate, process_input) else: result = obj.communicate(process_input) obj.stdin.close() # pylint: disable=E1101 _returncode = obj.returncode # pylint: disable=E1101 LOG.log(loglevel, 'CMD "%s" returned: %s in %0.3fs', sanitized_cmd, _returncode, watch.elapsed()) finally: if on_completion: on_completion(obj) if not ignore_exit_code and _returncode not in check_exit_code: (stdout, stderr) = result if six.PY3: stdout = os.fsdecode(stdout) stderr = os.fsdecode(stderr) 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) if six.PY3 and not binary and result is not None: (stdout, stderr) = result # Decode from the locale using using the surrogateescape error # handler (decoding cannot fail) stdout = os.fsdecode(stdout) stderr = os.fsdecode(stderr) return (stdout, stderr) else: return result except (ProcessExecutionError, OSError) as err: # if we want to always log the errors or if this is # the final attempt that failed and we want to log that. if log_errors == LOG_ALL_ERRORS or ( log_errors == LOG_FINAL_ERROR and not attempts): if isinstance(err, ProcessExecutionError): format = _('%(desc)r\ncommand: %(cmd)r\n' 'exit code: %(code)r\nstdout: %(stdout)r\n' 'stderr: %(stderr)r') LOG.log(loglevel, format, {"desc": err.description, "cmd": err.cmd, "code": err.exit_code, "stdout": err.stdout, "stderr": err.stderr}) else: format = _('Got an OSError\ncommand: %(cmd)r\n' 'errno: %(errno)r') LOG.log(loglevel, format, {"cmd": sanitized_cmd, "errno": err.errno}) if not attempts: LOG.log(loglevel, _('%r failed. Not Retrying.'), sanitized_cmd) raise else: LOG.log(loglevel, _('%r failed. Retrying.'), sanitized_cmd) if delay_on_retry: time.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 # NOTE(bnemec): termie's comment above is probably specific to the # eventlet subprocess module, but since we still # have to support that we're leaving the sleep. It # won't hurt anything in the stdlib case anyway. time.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. :param discard_warnings: True | False. Defaults to False. If set to True, then for succeeding commands, stderr is cleared :type discard_warnings: boolean :returns: (out, err) from process execution """ 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, binary=False, timeout=None, sanitize_stdout=True): """Run a command through SSH. :param ssh: An SSH Connection object. :param cmd: The command string to run. :param check_exit_code: If an exception should be raised for non-zero exit. :param timeout: Max time in secs to wait for command execution. :param sanitize_stdout: Defaults to True. If set to True, stdout is sanitized i.e. any sensitive information like password in command output will be masked. :returns: (stdout, stderr) from command execution through SSH. .. versionchanged:: 1.9 Added *binary* optional parameter. """ sanitized_cmd = strutils.mask_password(cmd) LOG.debug('Running cmd (SSH): %s', sanitized_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, timeout=timeout) 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() if six.PY3: # Decode from the locale using using the surrogateescape error handler # (decoding cannot fail). Decode even if binary is True because # mask_password() requires Unicode on Python 3 stdout = os.fsdecode(stdout) stderr = os.fsdecode(stderr) if sanitize_stdout: stdout = strutils.mask_password(stdout) stderr = strutils.mask_password(stderr) # 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: # In case of errors in command run, due to poor implementation of # command executable program, there might be chance that it leaks # sensitive information like password to stdout. In such cases # stdout needs to be sanitized even though sanitize_stdout=False. stdout = strutils.mask_password(stdout) raise ProcessExecutionError(exit_code=exit_status, stdout=stdout, stderr=stderr, cmd=sanitized_cmd) if binary: if six.PY2: # On Python 2, stdout is a bytes string if mask_password() failed # to decode it, or an Unicode string otherwise. Encode to the # default encoding (ASCII) because mask_password() decodes from # the same encoding. if isinstance(stdout, six.text_type): stdout = stdout.encode() if isinstance(stderr, six.text_type): stderr = stderr.encode() else: # fsencode() is the reverse operation of fsdecode() stdout = os.fsencode(stdout) stderr = os.fsencode(stderr) return (stdout, stderr) def get_worker_count(): """Utility to get the default worker count. :returns: 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