296 lines
12 KiB
Python
296 lines
12 KiB
Python
# Copyright 2019, David Wilson
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are met:
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#
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# 1. Redistributions of source code must retain the above copyright notice,
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# this list of conditions and the following disclaimer.
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#
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# 2. Redistributions in binary form must reproduce the above copyright notice,
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# this list of conditions and the following disclaimer in the documentation
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# and/or other materials provided with the distribution.
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#
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# 3. Neither the name of the copyright holder nor the names of its contributors
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# may be used to endorse or promote products derived from this software without
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# specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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# POSSIBILITY OF SUCH DAMAGE.
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from __future__ import absolute_import
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import os
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import signal
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import threading
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import mitogen.core
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import ansible_mitogen.affinity
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import ansible_mitogen.loaders
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import ansible_mitogen.mixins
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import ansible_mitogen.process
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import ansible
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import ansible.executor.process.worker
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ANSIBLE_VERSION_MIN = '2.3'
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ANSIBLE_VERSION_MAX = '2.7'
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NEW_VERSION_MSG = (
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"Your Ansible version (%s) is too recent. The most recent version\n"
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"supported by Mitogen for Ansible is %s.x. Please check the Mitogen\n"
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"release notes to see if a new version is available, otherwise\n"
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"subscribe to the corresponding GitHub issue to be notified when\n"
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"support becomes available.\n"
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"\n"
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" https://mitogen.rtfd.io/en/latest/changelog.html\n"
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" https://github.com/dw/mitogen/issues/\n"
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)
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OLD_VERSION_MSG = (
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"Your version of Ansible (%s) is too old. The oldest version supported by "
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"Mitogen for Ansible is %s."
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)
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def _assert_supported_release():
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"""
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Throw AnsibleError with a descriptive message in case of being loaded into
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an unsupported Ansible release.
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"""
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v = ansible.__version__
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if v[:len(ANSIBLE_VERSION_MIN)] < ANSIBLE_VERSION_MIN:
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raise ansible.errors.AnsibleError(
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OLD_VERSION_MSG % (v, ANSIBLE_VERSION_MIN)
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)
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if v[:len(ANSIBLE_VERSION_MAX)] > ANSIBLE_VERSION_MAX:
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raise ansible.errors.AnsibleError(
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NEW_VERSION_MSG % (ansible.__version__, ANSIBLE_VERSION_MAX)
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)
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def _patch_awx_callback():
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"""
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issue #400: AWX loads a display callback that suffers from thread-safety
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issues. Detect the presence of older AWX versions and patch the bug.
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"""
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# AWX uses sitecustomize.py to force-load this package. If it exists, we're
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# running under AWX.
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try:
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from awx_display_callback.events import EventContext
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from awx_display_callback.events import event_context
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except ImportError:
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return
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if hasattr(EventContext(), '_local'):
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# Patched version.
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return
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def patch_add_local(self, **kwargs):
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tls = vars(self._local)
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ctx = tls.setdefault('_ctx', {})
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ctx.update(kwargs)
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EventContext._local = threading.local()
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EventContext.add_local = patch_add_local
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_patch_awx_callback()
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def wrap_action_loader__get(name, *args, **kwargs):
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"""
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While the mitogen strategy is active, trap action_loader.get() calls,
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augmenting any fetched class with ActionModuleMixin, which replaces various
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helper methods inherited from ActionBase with implementations that avoid
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the use of shell fragments wherever possible.
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This is used instead of static subclassing as it generalizes to third party
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action modules outside the Ansible tree.
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"""
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klass = action_loader__get(name, class_only=True)
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if klass:
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bases = (ansible_mitogen.mixins.ActionModuleMixin, klass)
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adorned_klass = type(str(name), bases, {})
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if kwargs.get('class_only'):
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return adorned_klass
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return adorned_klass(*args, **kwargs)
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def wrap_connection_loader__get(name, *args, **kwargs):
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"""
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While the strategy is active, rewrite connection_loader.get() calls for
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some transports into requests for a compatible Mitogen transport.
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"""
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if name in ('docker', 'kubectl', 'jail', 'local', 'lxc',
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'lxd', 'machinectl', 'setns', 'ssh'):
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name = 'mitogen_' + name
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return connection_loader__get(name, *args, **kwargs)
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def wrap_worker__run(*args, **kwargs):
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"""
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While the strategy is active, rewrite connection_loader.get() calls for
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some transports into requests for a compatible Mitogen transport.
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"""
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# Ignore parent's attempts to murder us when we still need to write
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# profiling output.
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if mitogen.core._profile_hook.__name__ != '_profile_hook':
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signal.signal(signal.SIGTERM, signal.SIG_IGN)
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ansible_mitogen.logging.set_process_name('task')
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ansible_mitogen.affinity.policy.assign_worker()
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return mitogen.core._profile_hook('WorkerProcess',
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lambda: worker__run(*args, **kwargs)
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)
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class StrategyMixin(object):
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"""
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This mix-in enhances any built-in strategy by arranging for various Mitogen
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services to be initialized in the Ansible top-level process, and for worker
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processes to grow support for using those top-level services to communicate
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with and execute modules on remote hosts.
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Mitogen:
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A private Broker IO multiplexer thread is created to dispatch IO
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between the local Router and any connected streams, including streams
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connected to Ansible WorkerProcesses, and SSH commands implementing
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connections to remote machines.
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A Router is created that implements message dispatch to any locally
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registered handlers, and message routing for remote streams. Router is
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the junction point through which WorkerProceses and remote SSH contexts
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can communicate.
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Router additionally adds message handlers for a variety of base
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services, review the Standard Handles section of the How It Works guide
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in the documentation.
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A ContextService is installed as a message handler in the master
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process and run on a private thread. It is responsible for accepting
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requests to establish new SSH connections from worker processes, and
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ensuring precisely one connection exists and is reused for subsequent
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playbook steps. The service presently runs in a single thread, so to
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begin with, new SSH connections are serialized.
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Finally a mitogen.unix listener is created through which WorkerProcess
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can establish a connection back into the master process, in order to
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avail of ContextService. A UNIX listener socket is necessary as there
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is no more sane mechanism to arrange for IPC between the Router in the
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master process, and the corresponding Router in the worker process.
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Ansible:
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PluginLoader monkey patches are installed to catch attempts to create
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connection and action plug-ins.
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For connection plug-ins, if the desired method is "local" or "ssh", it
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is redirected to the "mitogen" connection plug-in. That plug-in
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implements communication via a UNIX socket connection to the top-level
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Ansible process, and uses ContextService running in the top-level
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process to actually establish and manage the connection.
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For action plug-ins, the original class is looked up as usual, but a
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new subclass is created dynamically in order to mix-in
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ansible_mitogen.target.ActionModuleMixin, which overrides many of the
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methods usually inherited from ActionBase in order to replace them with
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pure-Python equivalents that avoid the use of shell.
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In particular, _execute_module() is overridden with an implementation
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that uses ansible_mitogen.target.run_module() executed in the target
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Context. run_module() implements module execution by importing the
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module as if it were a normal Python module, and capturing its output
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in the remote process. Since the Mitogen module loader is active in the
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remote process, all the heavy lifting of transferring the action module
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and its dependencies are automatically handled by Mitogen.
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"""
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def _install_wrappers(self):
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"""
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Install our PluginLoader monkey patches and update global variables
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with references to the real functions.
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"""
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global action_loader__get
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action_loader__get = ansible_mitogen.loaders.action_loader.get
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ansible_mitogen.loaders.action_loader.get = wrap_action_loader__get
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global connection_loader__get
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connection_loader__get = ansible_mitogen.loaders.connection_loader.get
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ansible_mitogen.loaders.connection_loader.get = wrap_connection_loader__get
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global worker__run
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worker__run = ansible.executor.process.worker.WorkerProcess.run
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ansible.executor.process.worker.WorkerProcess.run = wrap_worker__run
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def _remove_wrappers(self):
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"""
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Uninstall the PluginLoader monkey patches.
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"""
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ansible_mitogen.loaders.action_loader.get = action_loader__get
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ansible_mitogen.loaders.connection_loader.get = connection_loader__get
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ansible.executor.process.worker.WorkerProcess.run = worker__run
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def _add_plugin_paths(self):
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"""
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Add the Mitogen plug-in directories to the ModuleLoader path, avoiding
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the need for manual configuration.
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"""
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base_dir = os.path.join(os.path.dirname(__file__), 'plugins')
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ansible_mitogen.loaders.connection_loader.add_directory(
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os.path.join(base_dir, 'connection')
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)
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ansible_mitogen.loaders.action_loader.add_directory(
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os.path.join(base_dir, 'action')
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)
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def _queue_task(self, host, task, task_vars, play_context):
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"""
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Many PluginLoader caches are defective as they are only populated in
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the ephemeral WorkerProcess. Touch each plug-in path before forking to
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ensure all workers receive a hot cache.
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"""
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ansible_mitogen.loaders.module_loader.find_plugin(
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name=task.action,
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mod_type='',
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)
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ansible_mitogen.loaders.connection_loader.get(
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name=play_context.connection,
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class_only=True,
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)
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ansible_mitogen.loaders.action_loader.get(
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name=task.action,
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class_only=True,
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)
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return super(StrategyMixin, self)._queue_task(
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host=host,
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task=task,
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task_vars=task_vars,
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play_context=play_context,
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)
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def run(self, iterator, play_context, result=0):
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"""
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Arrange for a mitogen.master.Router to be available for the duration of
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the strategy's real run() method.
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"""
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_assert_supported_release()
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ansible_mitogen.process.MuxProcess.start()
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run = super(StrategyMixin, self).run
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self._add_plugin_paths()
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self._install_wrappers()
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try:
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return mitogen.core._profile_hook('Strategy',
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lambda: run(iterator, play_context)
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)
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finally:
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self._remove_wrappers()
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