ansible_mitogen: Fix errant ModuleNotFoundError blacklist exceptions

Current module whitelist/blacklist behaviour is to reject any module not on
the whitelist if the whitelist is populated. Adding `ansible` and
`ansible_mitogen` to the whitelist effectively blocklisted every other Python
module/package, negating much of the benefit of Mitogen.

Fixes #1011

.ci/azure-pipelines.yml

@@ -33,13 +33,9 @@ jobs:
 
       # NOTE: this hangs when ran in Ubuntu 18.04
       Van_27_210:
-        tox.env: py27-mode_localhost-ansible2.10
-        STRATEGY: linear
-        ANSIBLE_SKIP_TAGS: resource_intensive
+        tox.env: py27-mode_localhost-ansible2.10-strategy_linear
       Van_27_4:
-        tox.env: py27-mode_localhost-ansible4
-        STRATEGY: linear
-        ANSIBLE_SKIP_TAGS: resource_intensive
+        tox.env: py27-mode_localhost-ansible4-strategy_linear
 
 - job: Linux
   pool:

ansible_mitogen/process.py

@@ -180,29 +180,6 @@ def setup_pool(pool):
     LOG.debug('Service pool configured: size=%d', pool.size)
 
 
-def _setup_responder(responder):
-    """
-    Configure :class:`mitogen.master.ModuleResponder` to only permit
-    certain packages, and to generate custom responses for certain modules.
-    """
-    responder.whitelist_prefix('ansible')
-    responder.whitelist_prefix('ansible_mitogen')
-
-    # Ansible 2.3 is compatible with Python 2.4 targets, however
-    # ansible/__init__.py is not. Instead, executor/module_common.py writes
-    # out a 2.4-compatible namespace package for unknown reasons. So we
-    # copy it here.
-    responder.add_source_override(
-        fullname='ansible',
-        path=ansible.__file__,
-        source=(ANSIBLE_PKG_OVERRIDE % (
-            ansible.__version__,
-            ansible.__author__,
-        )).encode(),
-        is_pkg=True,
-    )
-
-
 def increase_open_file_limit():
     """
     #549: in order to reduce the possibility of hitting an open files limit,
@@ -669,7 +646,6 @@ def _setup_master(self):
             broker=self.broker,
             max_message_size=MAX_MESSAGE_SIZE,
         )
-        _setup_responder(self.router.responder)
         mitogen.core.listen(self.broker, 'shutdown', self._on_broker_shutdown)
         mitogen.core.listen(self.broker, 'exit', self._on_broker_exit)
         self.listener = mitogen.unix.Listener.build_stream(

tests/ansible/integration/all.yml

@@ -29,6 +29,8 @@
   tags: playbook_semantics
 - import_playbook: process/all.yml
   tags: process
+- import_playbook: responder/all.yml
+  tags: responder
 - import_playbook: runner/all.yml
   tags: runner
 - import_playbook: ssh/all.yml

tests/ansible/integration/responder/all.yml

@@ -0,0 +1 @@
+- import_playbook: imports.yml

tests/ansible/integration/responder/imports.yml

@@ -0,0 +1,23 @@
+- name: integration/responder/imports.yml
+  hosts: test-targets
+  tasks:
+    - meta: end_play
+      when: not is_mitogen
+
+    - name: Import pure Python module via Ansible module
+      mitogen_plain_old_add:
+        x: 2
+        y: 2
+      register: mitogen_plain_old_add_result
+
+    - name: Import binary module via Responder
+      custom_python_run_script:
+        script: |
+          import lxml
+      register: binary_module_result
+
+    - name: Import missing module via Responder
+      custom_python_run_script:
+        script: |
+          import does_not_exist
+      register: missing_module_result

tests/ansible/lib/modules/mitogen_plain_old_add.py

@@ -0,0 +1,36 @@
+#!/usr/bin/env python
+
+DOCUMENTATION = '''
+module: mitogen_plain_old_add
+options:
+    x: {type: int, required: true}
+    y: {type: int, required: true}
+author:
+    - Alex Willmer (@moreati)
+'''
+
+RETURN = '''
+total: {type: int, returned: always, sample: 42}
+'''
+
+from ansible.module_utils.basic import AnsibleModule
+
+import plain_old_module
+
+def main():
+    module = AnsibleModule(
+        argument_spec={
+            'x': {'type': int, 'required': True},
+            'x': {'type': int, 'required': True},
+        },
+        supports_check_mode=True,
+    )
+    result = {
+        'changed': False,
+        'total': plain_old_module.add(module.params['x'], module.params['y']),
+    }
+    module.exit_json(**result)
+
+
+if __name__ == '__main__':
+    main()

tests/ansible/run_ansible_playbook.py

@@ -35,6 +35,8 @@
     os.environ['PATH'],
 )
 
+os.environ['PYTHONPATH'] = os.path.join(GIT_BASEDIR, 'tests', 'data')
+
 extra = {
     'is_mitogen': os.environ.get('ANSIBLE_STRATEGY', '').startswith('mitogen'),
     'git_basedir': GIT_BASEDIR,