module compat for py3.8+ controller (#73423)

* module compat for py3.8+ controller

* replaced internal usages of selinux bindings with internal ctypes binding (allows basic selinux operations from any Python interpreter), plus tests

* added new respawn_module API to allow modules to import Python packages that are only available under a well-known interpreter, plus tests

* added respawn logic to modules that need Python libs from a specific system interpreter (apt, apt_repository, dnf, yum)

minimize internal HAVE_SELINUX usage

spurious junk

pep8

* pylint fixes

* add RHEL8 Python 3.8 testing

* more pylint

* import sanity

* unit tests

* changelog update

* fix a bunch of stuff

* tweak changelog

* fix setup_rpm_repo on EL8

* misc sanity/test fixes

* misc feedback tweaks

* fix import fallback in test module

* fix selinux MU test

* fix dnf tests to avoid python-dependent test packages

* add trailing LFs to aliases

* fix yum tests to avoid test package with Python deps

* hack create_repo for EL6 to create noarch package

1 files changed, 34 insertions, 42 deletions

diff --git a/lib/ansible/modules/dnf.py b/lib/ansible/modules/dnf.py
index 7550b3371f..b3a73fc1a4 100644
--- a/lib/ansible/modules/dnf.py
+++ b/lib/ansible/modules/dnf.py
@@ -324,6 +324,15 @@ import os
 import re
 import sys
 
+from ansible.module_utils._text import to_native, to_text
+from ansible.module_utils.urls import fetch_file
+from ansible.module_utils.six import PY2, text_type
+from distutils.version import LooseVersion
+
+from ansible.module_utils.basic import AnsibleModule
+from ansible.module_utils.common.respawn import has_respawned, probe_interpreters_for_module, respawn_module
+from ansible.module_utils.yumdnf import YumDnf, yumdnf_argument_spec
+
 try:
     import dnf
     import dnf.cli
@@ -335,14 +344,6 @@ try:
 except ImportError:
     HAS_DNF = False
 
-from ansible.module_utils._text import to_native, to_text
-from ansible.module_utils.urls import fetch_file
-from ansible.module_utils.six import PY2, text_type
-from distutils.version import LooseVersion
-
-from ansible.module_utils.basic import AnsibleModule
-from ansible.module_utils.yumdnf import YumDnf, yumdnf_argument_spec
-
 
 class DnfModule(YumDnf):
     """
@@ -509,40 +510,31 @@ class DnfModule(YumDnf):
         return rc
 
     def _ensure_dnf(self):
-        if not HAS_DNF:
-            if PY2:
-                package = 'python2-dnf'
-            else:
-                package = 'python3-dnf'
-
-            if self.module.check_mode:
-                self.module.fail_json(
-                    msg="`{0}` is not installed, but it is required"
-                    "for the Ansible dnf module.".format(package),
-                    results=[],
-                )
-
-            rc, stdout, stderr = self.module.run_command(['dnf', 'install', '-y', package])
-            global dnf
-            try:
-                import dnf
-                import dnf.cli
-                import dnf.const
-                import dnf.exceptions
-                import dnf.subject
-                import dnf.util
-            except ImportError:
-                self.module.fail_json(
-                    msg="Could not import the dnf python module using {0} ({1}). "
-                        "Please install `{2}` package or ensure you have specified the "
-                        "correct ansible_python_interpreter.".format(sys.executable, sys.version.replace('\n', ''),
-                                                                     package),
-                    results=[],
-                    cmd='dnf install -y {0}'.format(package),
-                    rc=rc,
-                    stdout=stdout,
-                    stderr=stderr,
-                )
+        if HAS_DNF:
+            return
+
+        system_interpreters = ['/usr/libexec/platform-python',
+                               '/usr/bin/python3',
+                               '/usr/bin/python2',
+                               '/usr/bin/python']
+
+        if not has_respawned():
+            # probe well-known system Python locations for accessible bindings, favoring py3
+            interpreter = probe_interpreters_for_module(system_interpreters, 'dnf')
+
+            if interpreter:
+                # respawn under the interpreter where the bindings should be found
+                respawn_module(interpreter)
+                # end of the line for this module, the process will exit here once the respawned module completes
+
+        # done all we can do, something is just broken (auto-install isn't useful anymore with respawn, so it was removed)
+        self.module.fail_json(
+            msg="Could not import the dnf python module using {0} ({1}). "
+                "Please install `python3-dnf` or `python2-dnf` package or ensure you have specified the "
+                "correct ansible_python_interpreter. (attempted {2})"
+                .format(sys.executable, sys.version.replace('\n', ''), system_interpreters),
+            results=[]
+        )
 
     def _configure_base(self, base, conf_file, disable_gpg_check, installroot='/'):
         """Configure the dnf Base object."""