Add install_python_debian parameter to deb822_repository (#85487)

* Add python3-debian dependency installation in module

* Add tests to exercise automatic dependency installation

* Fix broken tests to include new module parameter

Co-authored-by: Abhijeet Kasurde <akasurde@redhat.com>

changelogs/fragments/85487-add-dependency-installation-to-deb822_repository.yml

@@ -0,0 +1,2 @@
+minor_changes:
+  - deb822_repository - Add automatic installation of the ``python3-debian`` package if it is missing by adding the parameter ``install_python_debian``

lib/ansible/modules/deb822_repository.py

@@ -67,6 +67,17 @@ options:
         - Determines the path to the C(InRelease) file, relative to the normal
           position of an C(InRelease) file.
         type: str
+    install_python_debian:
+        description:
+        - Whether to automatically try to install the Python C(debian) library or not, if it is not already installed.
+          Without this library, the module does not work.
+            - Runs C(apt install python3-debian).
+            - Only works with the system Python. If you are using a Python on the remote that is not
+              the system Python, set O(install_python_debian=false) and ensure that the Python C(debian) library
+              for your Python version is installed some other way.
+        type: bool
+        default: false
+        version_added: '2.20'
     languages:
         description:
         - Defines which languages information such as translated
@@ -228,6 +239,7 @@ key_filename:
 
 import os
 import re
+import sys
 import tempfile
 import textwrap
 
@@ -235,6 +247,7 @@ from ansible.module_utils.basic import AnsibleModule
 from ansible.module_utils.basic import missing_required_lib
 from ansible.module_utils.common.collections import is_sequence
 from ansible.module_utils.common.file import S_IRWXU_RXG_RXO, S_IRWU_RG_RO
+from ansible.module_utils.common.respawn import has_respawned, probe_interpreters_for_module, respawn_module
 from ansible.module_utils.common.text.converters import to_bytes
 from ansible.module_utils.common.text.converters import to_native
 from ansible.module_utils.six import raise_from  # type: ignore[attr-defined]
@@ -357,6 +370,21 @@ def write_signed_by_key(module, v, slug):
     return changed, filename, None
 
 
+def install_python_debian(module, deb_pkg_name):
+
+    if not module.check_mode:
+        apt_path = module.get_bin_path('apt', required=True)
+        if apt_path:
+            rc, so, se = module.run_command([apt_path, 'update'])
+            if rc != 0:
+                module.fail_json(msg=f"Failed update while auto installing {deb_pkg_name} due to '{se.strip()}'")
+            rc, so, se = module.run_command([apt_path, 'install', deb_pkg_name, '-y', '-q'])
+            if rc != 0:
+                module.fail_json(msg=f"Failed to auto-install {deb_pkg_name} due to : '{se.strip()}'")
+    else:
+        module.fail_json(msg=f"{deb_pkg_name} must be installed to use check mode")
+
+
 def main():
     module = AnsibleModule(
         argument_spec={
@@ -395,6 +423,10 @@ def main():
             'inrelease_path': {
                 'type': 'str',
             },
+            'install_python_debian': {
+                'type': 'bool',
+                'default': False,
+            },
             'languages': {
                 'elements': 'str',
                 'type': 'list',
@@ -453,8 +485,53 @@ def main():
     )
 
     if not HAS_DEBIAN:
-        module.fail_json(msg=missing_required_lib("python3-debian"),
+        deb_pkg_name = 'python3-debian'
-                         exception=DEBIAN_IMP_ERR)
+        # This interpreter can't see the debian Python library- we'll do the following to try and fix that as per
+        # the apt_repository module:
+        # 1) look in common locations for system-owned interpreters that can see it; if we find one, respawn under it
+        # 2) finding none, try to install a matching python-debian package for the current interpreter version;
+        #    we limit to the current interpreter version to try and avoid installing a whole other Python just
+        #    for deb support
+        # 3) if we installed a support package, try to respawn under what we think is the right interpreter (could be
+        #    the current interpreter again, but we'll let it respawn anyway for simplicity)
+        # 4) if still not working, return an error and give up (some corner cases not covered, but this shouldn't be
+        #    made any more complex than it already is to try and cover more, eg, custom interpreters taking over
+        #    system locations)
+
+        if has_respawned():
+            # this shouldn't be possible; short-circuit early if it happens...
+            module.fail_json(msg=f"{deb_pkg_name} must be installed and visible from {sys.executable}.")
+
+        interpreters = ['/usr/bin/python3', '/usr/bin/python']
+
+        interpreter = probe_interpreters_for_module(interpreters, 'debian')
+
+        if interpreter:
+            # found the Python bindings; respawn this module under the interpreter where we found them
+            respawn_module(interpreter)
+            # this is the end of the line for this process, it will exit here once the respawned module has completed
+
+        # don't make changes if we're in check_mode
+        if module.check_mode:
+            module.fail_json(msg=f"{deb_pkg_name} must be installed to use check mode. If run with install_python_debian, this module can auto-install it.")
+
+        if module.params['install_python_debian']:
+            install_python_debian(module, deb_pkg_name)
+        else:
+            module.fail_json(msg=f'{deb_pkg_name} is not installed, and install_python_debian is False')
+
+        # try again to find the bindings in common places
+        interpreter = probe_interpreters_for_module(interpreters, 'debian')
+
+        if interpreter:
+            # found the Python bindings; respawn this module under the interpreter where we found them
+            # NB: respawn is somewhat wasteful if it's this interpreter, but simplifies the code
+            respawn_module(interpreter)
+            # this is the end of the line for this process, it will exit here once the respawned module has completed
+        else:
+            # we've done all we can do; just tell the user it's busted and get out
+            module.fail_json(msg=missing_required_lib(deb_pkg_name),
+                             exception=DEBIAN_IMP_ERR)
 
     check_mode = module.check_mode
 

test/integration/targets/deb822_repository/tasks/main.yml

@@ -1,13 +1,62 @@
 - meta: end_play
   when: ansible_os_family != 'Debian'
 
+- set_fact:
+    python_debian: python3-debian
+
 - block:
+    # UNINSTALL 'python3-debian'
+    #  The `deb822_repository` module has the smarts to auto-install `python3-debian`.  To
+    # test, we will first uninstall `python3-debian`.
+    - name: check {{ python_debian }} with dpkg
+      shell: dpkg -s {{ python_debian }}
+      register: dpkg_result
+      ignore_errors: true
+
+    - name: uninstall {{ python_debian }} with apt
+      apt: pkg={{ python_debian }} state=absent purge=yes
+      register: apt_result
+      when: dpkg_result is successful
+
+    - name: check failure when python3-debian is absent
+      deb822_repository:
+        name: myrepo
+        types: deb
+        uris: "http://example.com/debian/"
+        suites: stable
+        components: main
+      register: no_python3_debian
+      ignore_errors: true
+
+    - name: Assert failure with absent python3-debian
+      assert:
+        that: no_python3_debian.msg is contains 'python3-debian is not installed'
+
+    - name: run deb822 to check for python3-debian installation
+      deb822_repository:
+        name: myrepo
+        types: deb
+        uris: "http://example.com/debian/"
+        suites: stable
+        components: main
+        install_python_debian: true
+
+    - name: Clean up the previously added basic Debian repository
+      deb822_repository:
+        name: myrepo
+        state: absent
+
     - name: install python3-debian
       apt:
         name: python3-debian
         state: present
       register: py3_deb_install
 
+    - name: assert python3-debian already installed
+      assert:
+        that:
+           - not py3_deb_install.changed
+
     - import_tasks: test.yml
 
     - import_tasks: install.yml

test/integration/targets/deb822_repository/tasks/test.yml

@@ -119,6 +119,7 @@
     focal_archive_expected: |-
       Components: main restricted
       Date-Max-Future: 10
+      Install-Python-Debian: no
       X-Repolib-Name: ansible-test focal archive
       Suites: focal focal-updates
       Types: deb
@@ -192,6 +193,7 @@
   vars:
     signed_by_inline_expected: |-
       Components: main contrib non-free
+      Install-Python-Debian: no
       X-Repolib-Name: ansible-test
       Signed-By:
           -----BEGIN PGP PUBLIC KEY BLOCK-----