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mitogen/ansible_mitogen/target.py

673 lines
22 KiB
Python

# Copyright 2017, David Wilson
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# 1. Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
#
# 2. Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
#
# 3. Neither the name of the copyright holder nor the names of its contributors
# may be used to endorse or promote products derived from this software without
# specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
"""
Helper functions intended to be executed on the target. These are entrypoints
for file transfer, module execution and sundry bits like changing file modes.
"""
from __future__ import absolute_import
from __future__ import unicode_literals
import errno
import functools
import grp
import json
import logging
import operator
import os
import pwd
import re
import signal
import stat
import subprocess
import sys
import tempfile
import traceback
import types
import mitogen.core
import mitogen.fork
import mitogen.parent
import mitogen.service
# Ansible since PR #41749 inserts "import __main__" into
# ansible.module_utils.basic. Mitogen's importer will refuse such an import, so
# we must setup a fake "__main__" before that module is ever imported. The
# str() is to cast Unicode to bytes on Python 2.6.
if not sys.modules.get(str('__main__')):
sys.modules[str('__main__')] = types.ModuleType(str('__main__'))
import ansible.module_utils.json_utils
import ansible_mitogen.runner
LOG = logging.getLogger(__name__)
MAKE_TEMP_FAILED_MSG = (
"Unable to find a useable temporary directory. This likely means no\n"
"system-supplied TMP directory can be written to, or all directories\n"
"were mounted on 'noexec' filesystems.\n"
"\n"
"The following paths were tried:\n"
" %(namelist)s\n"
"\n"
"Please check '-vvv' output for a log of individual path errors."
)
#: Initialized to an econtext.parent.Context pointing at a pristine fork of
#: the target Python interpreter before it executes any code or imports.
_fork_parent = None
#: Set by init_child() to a list of candidate $variable-expanded and
#: tilde-expanded directory paths that may be usable as a temporary directory.
_candidate_temp_dirs = None
#: Set by reset_temp_dir() to the single temporary directory that will exist
#: for the duration of the process.
temp_dir = None
def get_small_file(context, path):
"""
Basic in-memory caching module fetcher. This generates an one roundtrip for
every previously unseen file, so it is only a temporary solution.
:param context:
Context we should direct FileService requests to. For now (and probably
forever) this is just the top-level Mitogen connection manager process.
:param path:
Path to fetch from FileService, must previously have been registered by
a privileged context using the `register` command.
:returns:
Bytestring file data.
"""
pool = mitogen.service.get_or_create_pool(router=context.router)
service = pool.get_service('mitogen.service.PushFileService')
return service.get(path)
def transfer_file(context, in_path, out_path, sync=False, set_owner=False):
"""
Streamily download a file from the connection multiplexer process in the
controller.
:param mitogen.core.Context context:
Reference to the context hosting the FileService that will be used to
fetch the file.
:param bytes in_path:
FileService registered name of the input file.
:param bytes out_path:
Name of the output path on the local disk.
:param bool sync:
If :data:`True`, ensure the file content and metadat are fully on disk
before renaming the temporary file over the existing file. This should
ensure in the case of system crash, either the entire old or new file
are visible post-reboot.
:param bool set_owner:
If :data:`True`, look up the metadata username and group on the local
system and file the file owner using :func:`os.fchmod`.
"""
out_path = os.path.abspath(out_path)
fd, tmp_path = tempfile.mkstemp(suffix='.tmp',
prefix='.ansible_mitogen_transfer-',
dir=os.path.dirname(out_path))
fp = os.fdopen(fd, 'wb', mitogen.core.CHUNK_SIZE)
LOG.debug('transfer_file(%r) temporary file: %s', out_path, tmp_path)
try:
try:
ok, metadata = mitogen.service.FileService.get(
context=context,
path=in_path,
out_fp=fp,
)
if not ok:
raise IOError('transfer of %r was interrupted.' % (in_path,))
os.fchmod(fp.fileno(), metadata['mode'])
if set_owner:
set_fd_owner(fp.fileno(), metadata['owner'], metadata['group'])
finally:
fp.close()
if sync:
os.fsync(fp.fileno())
os.rename(tmp_path, out_path)
except BaseException:
os.unlink(tmp_path)
raise
os.utime(out_path, (metadata['atime'], metadata['mtime']))
def prune_tree(path):
"""
Like shutil.rmtree(), but log errors rather than discard them, and do not
waste multiple os.stat() calls discovering whether the object can be
deleted, just try deleting it instead.
"""
try:
os.unlink(path)
return
except OSError as e:
if not (os.path.isdir(path) and
e.args[0] in (errno.EPERM, errno.EISDIR)):
LOG.error('prune_tree(%r): %s', path, e)
return
try:
# Ensure write access for readonly directories. Ignore error in case
# path is on a weird filesystem (e.g. vfat).
os.chmod(path, int('0700', 8))
except OSError as e:
LOG.warning('prune_tree(%r): %s', path, e)
try:
for name in os.listdir(path):
if name not in ('.', '..'):
prune_tree(os.path.join(path, name))
os.rmdir(path)
except OSError as e:
LOG.error('prune_tree(%r): %s', path, e)
def _on_broker_shutdown():
"""
Respond to broker shutdown (graceful termination by parent, or loss of
connection to parent) by deleting our sole temporary directory.
"""
prune_tree(temp_dir)
def find_good_temp_dir():
"""
Given a list of candidate temp directories extracted from ``ansible.cfg``
and stored in _candidate_temp_dirs, combine it with the Python-builtin list
of candidate directories used by :mod:`tempfile`, then iteratively try each
in turn until one is found that is both writeable and executable.
"""
paths = [os.path.expandvars(os.path.expanduser(p))
for p in _candidate_temp_dirs]
paths.extend(tempfile._candidate_tempdir_list())
for path in paths:
try:
tmp = tempfile.NamedTemporaryFile(
prefix='ansible_mitogen_find_good_temp_dir',
dir=path,
)
except (OSError, IOError) as e:
LOG.debug('temp dir %r unusable: %s', path, e)
continue
try:
try:
os.chmod(tmp.name, int('0700', 8))
except OSError as e:
LOG.debug('temp dir %r unusable: %s: chmod failed: %s',
path, e)
continue
try:
# access(.., X_OK) is sufficient to detect noexec.
if not os.access(tmp.name, os.X_OK):
raise OSError('filesystem appears to be mounted noexec')
except OSError as e:
LOG.debug('temp dir %r unusable: %s: %s', path, e)
continue
LOG.debug('Selected temp directory: %r (from %r)', path, paths)
return path
finally:
tmp.close()
raise IOError(MAKE_TEMP_FAILED_MSG % {
'paths': '\n '.join(paths),
})
@mitogen.core.takes_econtext
def reset_temp_dir(econtext):
"""
Create one temporary directory to be reused by all runner.py invocations
for the lifetime of the process. The temporary directory is changed for
each forked job, and emptied as necessary by runner.py::_cleanup_temp()
after each module invocation.
The result is that a context need only create and delete one directory
during startup and shutdown, and no further filesystem writes need occur
assuming no modules execute that create temporary files.
"""
global temp_dir
# https://github.com/dw/mitogen/issues/239
basedir = find_good_temp_dir()
temp_dir = tempfile.mkdtemp(prefix='ansible_mitogen_', dir=basedir)
# This must be reinstalled in forked children too, since the Broker
# instance from the parent process does not carry over to the new child.
mitogen.core.listen(econtext.broker, 'shutdown', _on_broker_shutdown)
@mitogen.core.takes_econtext
def init_child(econtext, log_level, candidate_temp_dirs):
"""
Called by ContextService immediately after connection; arranges for the
(presently) spotless Python interpreter to be forked, where the newly
forked interpreter becomes the parent of any newly forked future
interpreters.
This is necessary to prevent modules that are executed in-process from
polluting the global interpreter state in a way that effects explicitly
isolated modules.
:param int log_level:
Logging package level active in the master.
:param list[str] candidate_temp_dirs:
List of $variable-expanded and tilde-expanded directory names to add to
candidate list of temporary directories.
:returns:
Dict like::
{
'fork_context': mitogen.core.Context.
'home_dir': str.
}
Where `fork_context` refers to the newly forked 'fork parent' context
the controller will use to start forked jobs, and `home_dir` is the
home directory for the active user account.
"""
global _candidate_temp_dirs
_candidate_temp_dirs = candidate_temp_dirs
global _fork_parent
mitogen.parent.upgrade_router(econtext)
_fork_parent = econtext.router.fork()
reset_temp_dir(econtext)
# Copying the master's log level causes log messages to be filtered before
# they reach LogForwarder, thus reducing an influx of tiny messges waking
# the connection multiplexer process in the master.
LOG.setLevel(log_level)
logging.getLogger('ansible_mitogen').setLevel(log_level)
return {
'fork_context': _fork_parent,
'home_dir': mitogen.core.to_text(os.path.expanduser('~')),
'temp_dir': temp_dir,
}
@mitogen.core.takes_econtext
def create_fork_child(econtext):
"""
For helper functions executed in the fork parent context, arrange for
the context's router to be upgraded as necessary and for a new child to be
prepared.
"""
mitogen.parent.upgrade_router(econtext)
context = econtext.router.fork()
context.call(reset_temp_dir)
LOG.debug('create_fork_child() -> %r', context)
return context
def run_module(kwargs):
"""
Set up the process environment in preparation for running an Ansible
module. This monkey-patches the Ansible libraries in various places to
prevent it from trying to kill the process on completion, and to prevent it
from reading sys.stdin.
"""
runner_name = kwargs.pop('runner_name')
klass = getattr(ansible_mitogen.runner, runner_name)
impl = klass(**kwargs)
return impl.run()
def _get_async_dir():
return os.path.expanduser(
os.environ.get('ANSIBLE_ASYNC_DIR', '~/.ansible_async')
)
class AsyncRunner(object):
def __init__(self, job_id, timeout_secs, econtext, kwargs):
self.job_id = job_id
self.timeout_secs = timeout_secs
self.econtext = econtext
self.kwargs = kwargs
self._timed_out = False
self._init_path()
def _init_path(self):
async_dir = _get_async_dir()
if not os.path.exists(async_dir):
os.makedirs(async_dir)
self.path = os.path.join(async_dir, self.job_id)
def _update(self, dct):
"""
Update an async job status file.
"""
LOG.info('%r._update(%r, %r)', self, self.job_id, dct)
dct.setdefault('ansible_job_id', self.job_id)
dct.setdefault('data', '')
with open(self.path + '.tmp', 'w') as fp:
fp.write(json.dumps(dct))
os.rename(self.path + '.tmp', self.path)
def _on_sigalrm(self, signum, frame):
"""
Respond to SIGALRM (job timeout) by updating the job file and killing
the process.
"""
msg = "Job reached maximum time limit of %d seconds." % (
self.timeout_secs,
)
self._update({
"failed": 1,
"finished": 1,
"msg": msg,
})
self._timed_out = True
self.econtext.broker.shutdown()
def _install_alarm(self):
signal.signal(signal.SIGALRM, self._on_sigalrm)
signal.alarm(self.timeout_secs)
def _run_module(self):
kwargs = dict(self.kwargs, **{
'detach': True,
'econtext': self.econtext,
'emulate_tty': False,
})
return run_module(kwargs)
def _parse_result(self, dct):
filtered, warnings = (
ansible.module_utils.json_utils.
_filter_non_json_lines(dct['stdout'])
)
result = json.loads(filtered)
result.setdefault('warnings', []).extend(warnings)
result['stderr'] = dct['stderr']
self._update(result)
def _run(self):
"""
1. Immediately updates the status file to mark the job as started.
2. Installs a timer/signal handler to implement the time limit.
3. Runs as with run_module(), writing the result to the status file.
:param dict kwargs:
Runner keyword arguments.
:param str job_id:
String job ID.
:param int timeout_secs:
If >0, limit the task's maximum run time.
"""
self._update({
'started': 1,
'finished': 0,
'pid': os.getpid()
})
if self.timeout_secs > 0:
self._install_alarm()
dct = self._run_module()
if not self._timed_out:
# After SIGALRM fires, there is a window between broker responding
# to shutdown() by killing the process, and work continuing on the
# main thread. If main thread was asleep in at least
# basic.py/select.select(), an EINTR will be raised. We want to
# discard that exception.
try:
self._parse_result(dct)
except Exception:
self._update({
"failed": 1,
"msg": traceback.format_exc(),
"data": dct['stdout'], # temporary notice only
"stderr": dct['stderr']
})
def run(self):
try:
try:
self._run()
except Exception:
self._update({
"failed": 1,
"msg": traceback.format_exc(),
})
finally:
self.econtext.broker.shutdown()
@mitogen.core.takes_econtext
def run_module_async(kwargs, job_id, timeout_secs, econtext):
"""
Execute a module with its run status and result written to a file,
terminating on the process on completion. This function must run in a child
forked using :func:`create_fork_child`.
"""
arunner = AsyncRunner(job_id, timeout_secs, econtext, kwargs)
arunner.run()
def get_user_shell():
"""
For commands executed directly via an SSH command-line, SSH looks up the
user's shell via getpwuid() and only defaults to /bin/sh if that field is
missing or empty.
"""
try:
pw_shell = pwd.getpwuid(os.geteuid()).pw_shell
except KeyError:
pw_shell = None
return pw_shell or '/bin/sh'
def exec_args(args, in_data='', chdir=None, shell=None, emulate_tty=False):
"""
Run a command in a subprocess, emulating the argument handling behaviour of
SSH.
:param list[str]:
Argument vector.
:param bytes in_data:
Optional standard input for the command.
:param bool emulate_tty:
If :data:`True`, arrange for stdout and stderr to be merged into the
stdout pipe and for LF to be translated into CRLF, emulating the
behaviour of a TTY.
:return:
(return code, stdout bytes, stderr bytes)
"""
LOG.debug('exec_args(%r, ..., chdir=%r)', args, chdir)
assert isinstance(args, list)
if emulate_tty:
stderr = subprocess.STDOUT
else:
stderr = subprocess.PIPE
proc = subprocess.Popen(
args=args,
stdout=subprocess.PIPE,
stderr=stderr,
stdin=subprocess.PIPE,
cwd=chdir,
)
stdout, stderr = proc.communicate(in_data)
if emulate_tty:
stdout = stdout.replace(b'\n', b'\r\n')
return proc.returncode, stdout, stderr or ''
def exec_command(cmd, in_data='', chdir=None, shell=None, emulate_tty=False):
"""
Run a command in a subprocess, emulating the argument handling behaviour of
SSH.
:param bytes cmd:
String command line, passed to user's shell.
:param bytes in_data:
Optional standard input for the command.
:return:
(return code, stdout bytes, stderr bytes)
"""
assert isinstance(cmd, mitogen.core.UnicodeType)
return exec_args(
args=[get_user_shell(), '-c', cmd],
in_data=in_data,
chdir=chdir,
shell=shell,
emulate_tty=emulate_tty,
)
def read_path(path):
"""
Fetch the contents of a filesystem `path` as bytes.
"""
return open(path, 'rb').read()
def set_fd_owner(fd, owner, group=None):
if owner:
uid = pwd.getpwnam(owner).pw_uid
else:
uid = os.geteuid()
if group:
gid = grp.getgrnam(group).gr_gid
else:
gid = os.getegid()
os.fchown(fd, (uid, gid))
def write_path(path, s, owner=None, group=None, mode=None,
utimes=None, sync=False):
"""
Writes bytes `s` to a filesystem `path`.
"""
path = os.path.abspath(path)
fd, tmp_path = tempfile.mkstemp(suffix='.tmp',
prefix='.ansible_mitogen_transfer-',
dir=os.path.dirname(path))
fp = os.fdopen(fd, 'wb', mitogen.core.CHUNK_SIZE)
LOG.debug('write_path(path=%r) temporary file: %s', path, tmp_path)
try:
try:
if mode:
os.fchmod(fp.fileno(), mode)
if owner or group:
set_fd_owner(fp.fileno(), owner, group)
fp.write(s)
finally:
fp.close()
if sync:
os.fsync(fp.fileno())
os.rename(tmp_path, path)
except BaseException:
os.unlink(tmp_path)
raise
if utimes:
os.utime(path, utimes)
CHMOD_CLAUSE_PAT = re.compile(r'([uoga]*)([+\-=])([ugo]|[rwx]*)')
CHMOD_MASKS = {
'u': stat.S_IRWXU,
'g': stat.S_IRWXG,
'o': stat.S_IRWXO,
'a': (stat.S_IRWXU | stat.S_IRWXG | stat.S_IRWXO),
}
CHMOD_BITS = {
'u': {'r': stat.S_IRUSR, 'w': stat.S_IWUSR, 'x': stat.S_IXUSR},
'g': {'r': stat.S_IRGRP, 'w': stat.S_IWGRP, 'x': stat.S_IXGRP},
'o': {'r': stat.S_IROTH, 'w': stat.S_IWOTH, 'x': stat.S_IXOTH},
'a': {
'r': (stat.S_IRUSR | stat.S_IRGRP | stat.S_IROTH),
'w': (stat.S_IWUSR | stat.S_IWGRP | stat.S_IWOTH),
'x': (stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH)
}
}
def apply_mode_spec(spec, mode):
"""
Given a symbolic file mode change specification in the style of chmod(1)
`spec`, apply changes in the specification to the numeric file mode `mode`.
"""
for clause in spec.split(','):
match = CHMOD_CLAUSE_PAT.match(clause)
who, op, perms = match.groups()
for ch in who or 'a':
mask = CHMOD_MASKS[ch]
bits = CHMOD_BITS[ch]
cur_perm_bits = mode & mask
new_perm_bits = functools.reduce(operator.or_, (bits[p] for p in perms), 0)
mode &= ~mask
if op == '=':
mode |= new_perm_bits
elif op == '+':
mode |= new_perm_bits | cur_perm_bits
else:
mode |= cur_perm_bits & ~new_perm_bits
return mode
def set_file_mode(path, spec):
"""
Update the permissions of a file using the same syntax as chmod(1).
"""
mode = os.stat(path).st_mode
if spec.isdigit():
new_mode = int(spec, 8)
else:
new_mode = apply_mode_spec(spec, mode)
os.chmod(path, new_mode)