1 files changed, 98 insertions, 0 deletions
diff --git a/lib/ansible/module_utils/common/respawn.py b/lib/ansible/module_utils/common/respawn.py
new file mode 100644
index 0000000..3bc526a
--- /dev/null
+++ b/lib/ansible/module_utils/common/respawn.py
@@ -0,0 +1,98 @@
+# Copyright: (c) 2021, Ansible Project
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+
+from __future__ import (absolute_import, division, print_function)
+__metaclass__ = type
+
+import os
+import subprocess
+import sys
+
+from ansible.module_utils.common.text.converters import to_bytes, to_native
+
+
+def has_respawned():
+    return hasattr(sys.modules['__main__'], '_respawned')
+
+
+def respawn_module(interpreter_path):
+    """
+    Respawn the currently-running Ansible Python module under the specified Python interpreter.
+
+    Ansible modules that require libraries that are typically available only under well-known interpreters
+    (eg, ``yum``, ``apt``, ``dnf``) can use bespoke logic to determine the libraries they need are not
+    available, then call `respawn_module` to re-execute the current module under a different interpreter
+    and exit the current process when the new subprocess has completed. The respawned process inherits only
+    stdout/stderr from the current process.
+
+    Only a single respawn is allowed. ``respawn_module`` will fail on nested respawns. Modules are encouraged
+    to call `has_respawned()` to defensively guide behavior before calling ``respawn_module``, and to ensure
+    that the target interpreter exists, as ``respawn_module`` will not fail gracefully.
+
+    :arg interpreter_path: path to a Python interpreter to respawn the current module
+    """
+
+    if has_respawned():
+        raise Exception('module has already been respawned')
+
+    # FUTURE: we need a safe way to log that a respawn has occurred for forensic/debug purposes
+    payload = _create_payload()
+    stdin_read, stdin_write = os.pipe()
+    os.write(stdin_write, to_bytes(payload))
+    os.close(stdin_write)
+    rc = subprocess.call([interpreter_path, '--'], stdin=stdin_read)
+    sys.exit(rc)  # pylint: disable=ansible-bad-function
+
+
+def probe_interpreters_for_module(interpreter_paths, module_name):
+    """
+    Probes a supplied list of Python interpreters, returning the first one capable of
+    importing the named module. This is useful when attempting to locate a "system
+    Python" where OS-packaged utility modules are located.
+
+    :arg interpreter_paths: iterable of paths to Python interpreters. The paths will be probed
+    in order, and the first path that exists and can successfully import the named module will
+    be returned (or ``None`` if probing fails for all supplied paths).
+    :arg module_name: fully-qualified Python module name to probe for (eg, ``selinux``)
+    """
+    for interpreter_path in interpreter_paths:
+        if not os.path.exists(interpreter_path):
+            continue
+        try:
+            rc = subprocess.call([interpreter_path, '-c', 'import {0}'.format(module_name)])
+            if rc == 0:
+                return interpreter_path
+        except Exception:
+            continue
+
+    return None
+
+
+def _create_payload():
+    from ansible.module_utils import basic
+    smuggled_args = getattr(basic, '_ANSIBLE_ARGS')
+    if not smuggled_args:
+        raise Exception('unable to access ansible.module_utils.basic._ANSIBLE_ARGS (not launched by AnsiballZ?)')
+    module_fqn = sys.modules['__main__']._module_fqn
+    modlib_path = sys.modules['__main__']._modlib_path
+    respawn_code_template = '''
+import runpy
+import sys
+
+module_fqn = '{module_fqn}'
+modlib_path = '{modlib_path}'
+smuggled_args = b"""{smuggled_args}""".strip()
+
+
+if __name__ == '__main__':
+    sys.path.insert(0, modlib_path)
+
+    from ansible.module_utils import basic
+    basic._ANSIBLE_ARGS = smuggled_args
+
+    runpy.run_module(module_fqn, init_globals=dict(_respawned=True), run_name='__main__', alter_sys=True)
+    '''
+
+    respawn_code = respawn_code_template.format(module_fqn=module_fqn, modlib_path=modlib_path, smuggled_args=to_native(smuggled_args))
+
+    return respawn_code