87 lines
3.3 KiB
Python
87 lines
3.3 KiB
Python
# Copyright: (c) 2021, Ansible Project
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# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
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from __future__ import annotations
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import os
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import pathlib
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import subprocess
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import sys
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import typing as t
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from ansible.module_utils.common.text.converters import to_bytes
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from ansible.module_utils._internal._ansiballz import _respawn
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_ANSIBLE_PARENT_PATH = pathlib.Path(__file__).parents[3]
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def has_respawned():
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return hasattr(sys.modules['__main__'], '_respawned')
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def respawn_module(interpreter_path) -> t.NoReturn:
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"""
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Respawn the currently-running Ansible Python module under the specified Python interpreter.
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Ansible modules that require libraries that are typically available only under well-known interpreters
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(eg, ``apt``, ``dnf``) can use bespoke logic to determine the libraries they need are not
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available, then call `respawn_module` to re-execute the current module under a different interpreter
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and exit the current process when the new subprocess has completed. The respawned process inherits only
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stdout/stderr from the current process.
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Only a single respawn is allowed. ``respawn_module`` will fail on nested respawns. Modules are encouraged
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to call `has_respawned()` to defensively guide behavior before calling ``respawn_module``, and to ensure
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that the target interpreter exists, as ``respawn_module`` will not fail gracefully.
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:arg interpreter_path: path to a Python interpreter to respawn the current module
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"""
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if has_respawned():
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raise Exception('module has already been respawned')
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# FUTURE: we need a safe way to log that a respawn has occurred for forensic/debug purposes
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payload = _respawn.create_payload()
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stdin_read, stdin_write = os.pipe()
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os.write(stdin_write, to_bytes(payload))
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os.close(stdin_write)
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rc = subprocess.call([interpreter_path, '--'], stdin=stdin_read)
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sys.exit(rc) # pylint: disable=ansible-bad-function
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def probe_interpreters_for_module(interpreter_paths, module_name):
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"""
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Probes a supplied list of Python interpreters, returning the first one capable of
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importing the named module. This is useful when attempting to locate a "system
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Python" where OS-packaged utility modules are located.
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:arg interpreter_paths: iterable of paths to Python interpreters. The paths will be probed
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in order, and the first path that exists and can successfully import the named module will
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be returned (or ``None`` if probing fails for all supplied paths).
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:arg module_name: fully-qualified Python module name to probe for (for example, ``selinux``)
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"""
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PYTHONPATH = os.getenv('PYTHONPATH', '')
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env = os.environ.copy()
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env.update({
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'PYTHONPATH': f'{_ANSIBLE_PARENT_PATH}:{PYTHONPATH}'.rstrip(': ')
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})
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for interpreter_path in interpreter_paths:
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if not os.path.exists(interpreter_path):
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continue
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try:
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rc = subprocess.call(
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[
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interpreter_path,
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'-c',
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f'import {module_name}, ansible.module_utils.basic',
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],
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env=env,
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)
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if rc == 0:
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return interpreter_path
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except Exception:
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continue
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return None
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