Merge pull request #1382 from moreati/issue1225-interpreter-python-fallback

ansible_mitogen: Use INTERPRETER_PYTHON_FALLBACK as python candidates

Author: moreati

ansible_mitogen/mixins.py

@@ -470,18 +470,7 @@ def _low_level_execute_command(self, cmd, sudoable=True, in_data=None,
         # chicken-and-egg issue, mitogen needs a python to run low_level_execute_command
         # which is required by Ansible's discover_interpreter function
         if self._mitogen_discovering_interpreter:
-            possible_pythons = [
-                '/usr/bin/python',
-                'python3',
-                'python3.7',
-                'python3.6',
-                'python3.5',
-                'python2.7',
-                'python2.6',
-                '/usr/libexec/platform-python',
-                '/usr/bin/python3',
-                'python'
-            ]
+            possible_pythons = self._mitogen_interpreter_candidates
         else:
             # not used, just adding a filler value
             possible_pythons = ['python']
@@ -492,12 +481,15 @@ def _low_level_execute_command(self, cmd, sudoable=True, in_data=None,
                 rc, stdout, stderr = self._connection.exec_command(
                     cmd, in_data, sudoable, mitogen_chdir=chdir,
                 )
-            # TODO: what exception is thrown?
-            except:
+            except BaseException as exc:
                 # we've reached the last python attempted and failed
                 if possible_python == possible_pythons[-1]:
                     raise
                 else:
+                    LOG.debug(
+                        '%r._low_level_execute_command: candidate=%r ignored: %s, %r',
+                        self, possible_python, type(exc), exc,
+                    )
                     continue
 
         stdout_text = to_text(stdout, errors=encoding_errors)

ansible_mitogen/transport_config.py

@@ -73,13 +73,21 @@
 from ansible.module_utils.six import with_metaclass
 from ansible.module_utils.parsing.convert_bool import boolean
 
+import ansible_mitogen.utils
 import mitogen.core
 
 
 LOG = logging.getLogger(__name__)
 
+if ansible_mitogen.utils.ansible_version[:2] >= (2, 19):
+    _FALLBACK_INTERPRETER = ansible.executor.interpreter_discovery._FALLBACK_INTERPRETER
+elif ansible_mitogen.utils.ansible_version[:2] >= (2, 17):
+    _FALLBACK_INTERPRETER = u'/usr/bin/python3'
+else:
+    _FALLBACK_INTERPRETER = u'/usr/bin/python'
 
-def run_interpreter_discovery_if_necessary(s, task_vars, action, rediscover_python):
+
+def run_interpreter_discovery_if_necessary(s, candidates, task_vars, action, rediscover_python):
     """
     Triggers ansible python interpreter discovery if requested.
     Caches this value the same way Ansible does it.
@@ -107,8 +115,11 @@ def run_interpreter_discovery_if_necessary(s, task_vars, action, rediscover_pyth
             # blow away the discovered_interpreter_config cache and rediscover
             del task_vars['ansible_facts'][discovered_interpreter_config]
 
-        if discovered_interpreter_config not in task_vars['ansible_facts']:
+        try:
+            s = task_vars[u'ansible_facts'][discovered_interpreter_config]
+        except KeyError:
             action._mitogen_discovering_interpreter = True
+            action._mitogen_interpreter_candidates = candidates
             # fake pipelining so discover_interpreter can be happy
             action._connection.has_pipelining = True
             s = ansible.executor.interpreter_discovery.discover_interpreter(
@@ -121,18 +132,17 @@ def run_interpreter_discovery_if_necessary(s, task_vars, action, rediscover_pyth
             # cache discovered interpreter
             task_vars['ansible_facts'][discovered_interpreter_config] = s
             action._connection.has_pipelining = False
-        else:
-            s = task_vars['ansible_facts'][discovered_interpreter_config]
 
         # propagate discovered interpreter as fact
         action._discovered_interpreter_key = discovered_interpreter_config
         action._discovered_interpreter = s
 
     action._mitogen_discovering_interpreter = False
+    action._mitogen_interpreter_candidates = None
     return s
 
 
-def parse_python_path(s, task_vars, action, rediscover_python):
+def parse_python_path(s, candidates, task_vars, action, rediscover_python):
     """
     Given the string set for ansible_python_interpeter, parse it using shell
     syntax and return an appropriate argument vector. If the value detected is
@@ -143,10 +153,9 @@ def parse_python_path(s, task_vars, action, rediscover_python):
         # if python_path doesn't exist, default to `auto` and attempt to discover it
         s = 'auto'
 
-    s = run_interpreter_discovery_if_necessary(s, task_vars, action, rediscover_python)
-    # if unable to determine python_path, fallback to '/usr/bin/python'
+    s = run_interpreter_discovery_if_necessary(s, candidates, task_vars, action, rediscover_python)
     if not s:
-        s = '/usr/bin/python'
+        s = _FALLBACK_INTERPRETER
 
     return ansible.utils.shlex.shlex_split(s)
 
@@ -510,13 +519,17 @@ def python_path(self, rediscover_python=False):
         interpreter_python = C.config.get_config_value(
             'INTERPRETER_PYTHON', variables=variables,
         )
+        interpreter_python_fallback = C.config.get_config_value(
+            'INTERPRETER_PYTHON_FALLBACK', variables=variables,
+        )
 
         if '{{' in interpreter_python or '{%' in interpreter_python:
             templar = self._connection.templar
             interpreter_python = templar.template(interpreter_python)
 
         return parse_python_path(
             interpreter_python,
+            candidates=interpreter_python_fallback,
             task_vars=self._task_vars,
             action=self._action,
             rediscover_python=rediscover_python)
@@ -732,11 +745,12 @@ def port(self):
 
     def python_path(self, rediscover_python=False):
         s = self._host_vars.get('ansible_python_interpreter')
-        # #511, #536: executor/module_common.py::_get_shebang() hard-wires
-        # "/usr/bin/python" as the default interpreter path if no other
-        # interpreter is specified.
+        interpreter_python_fallback = self._host_vars.get(
+            'ansible_interpreter_python_fallback', [],
+        )
         return parse_python_path(
             s,
+            candidates=interpreter_python_fallback,
             task_vars=self._task_vars,
             action=self._action,
             rediscover_python=rediscover_python)

docs/changelog.rst

@@ -21,6 +21,9 @@ To avail of fixes in an unreleased version, please download a ZIP file
 In progress (unreleased)
 ------------------------
 
+* :gh:issue:`1132` :mod:`ansible_mitogen` During intrepreter discovery use
+  Ansible ``INTERPRETER_PYTHON_FALLBACK`` config as list of candidates
+
 
 v0.3.34 (2025-11-27)
 --------------------