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mitogen/ansible_mitogen/helpers.py

294 lines
8.5 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.
from __future__ import absolute_import
import json
import logging
import operator
import os
import pwd
import random
import re
import stat
import subprocess
import tempfile
import threading
import zlib
import mitogen.core
import mitogen.service
import ansible_mitogen.runner
import ansible_mitogen.services
LOG = logging.getLogger(__name__)
#: Caching of fetched file data.
_file_cache = {}
#: Mapping of job_id<->result dict
_result_by_job_id = {}
#: Mapping of job_id<->threading.Thread
_thread_by_job_id = {}
def get_file(context, path):
"""
Basic in-memory caching module fetcher. This generates an one roundtrip for
every previously unseen module, so it is only temporary.
: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.
"""
if path not in _file_cache:
_file_cache[path] = zlib.decompress(
mitogen.service.call(
context,
ansible_mitogen.services.FileService.handle,
('fetch', path)
)
)
return _file_cache[path]
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 _async_main(job_id, runner_name, kwargs):
"""
Implementation for the thread that implements asynchronous module
execution.
"""
try:
rc = run_module(runner_name, kwargs)
except Exception, e:
rc = mitogen.core.CallError(e)
_result_by_job_id[job_id] = rc
def make_temp_directory(base_dir):
"""
Handle creation of `base_dir` if it is absent, in addition to a unique
temporary directory within `base_dir`.
:returns:
Newly created temporary directory.
"""
if not os.path.exists(base_dir):
os.makedirs(base_dir, mode=int('0700', 8))
return tempfile.mkdtemp(
dir=base_dir,
prefix='ansible-mitogen-tmp-',
)
def run_module_async(runner_name, kwargs):
"""
Arrange for an Ansible module to be executed in a thread of the current
process, with results available via :py:func:`get_async_result`.
"""
job_id = '%08x' % random.randint(0, 2**32-1)
_result_by_job_id[job_id] = None
_thread_by_job_id[job_id] = threading.Thread(
target=_async_main,
kwargs={
'job_id': job_id,
'runner_name': runner_name,
'kwargs': kwargs,
}
)
_thread_by_job_id[job_id].start()
return json.dumps({
'ansible_job_id': job_id,
'changed': True
})
def get_async_result(job_id):
"""
Poll for the result of an asynchronous task.
:param str job_id:
Job ID to poll for.
:returns:
``None`` if job is still running, JSON-encoded result dictionary if
execution completed normally, or :py:class:`mitogen.core.CallError` if
an exception was thrown.
"""
if not _thread_by_job_id[job_id].isAlive():
return _result_by_job_id[job_id]
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):
"""
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.
:return:
(return code, stdout bytes, stderr bytes)
"""
LOG.debug('exec_args(%r, ..., chdir=%r)', args, chdir)
assert isinstance(args, list)
proc = subprocess.Popen(
args=args,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
stdin=subprocess.PIPE,
cwd=chdir,
)
stdout, stderr = proc.communicate(in_data)
return proc.returncode, stdout, stderr
def exec_command(cmd, in_data='', chdir=None, shell=None):
"""
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, basestring)
return exec_args(
args=[get_user_shell(), '-c', cmd],
in_data=in_data,
chdir=chdir,
shell=shell,
)
def read_path(path):
"""
Fetch the contents of a filesystem `path` as bytes.
"""
return open(path, 'rb').read()
def write_path(path, s):
"""
Writes bytes `s` to a filesystem `path`.
"""
open(path, 'wb').write(s)
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 = 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)