issue #340: use expanded delegate_to hostname, not template.

PlayContext.delegate_to is the unexpanded template, Ansible doesn't keep
a copy of it around anywhere convenient. We either need to re-expand it
or take the expanded version that was stored on the Task, which is what
is done here.

ansible_mitogen/connection.py

@@ -448,7 +448,9 @@ class Connection(ansible.plugins.connection.ConnectionBase):
     #: Set to 'hostvars' by on_action_run()
     host_vars = None
 
-    #: Set to '_loader.get_basedir()' by on_action_run().
+    #: Set to '_loader.get_basedir()' by on_action_run(). Used by mitogen_local
+    #: to change the working directory to that of the current playbook,
+    #: matching vanilla Ansible behaviour.
     loader_basedir = None
 
     #: Set after connection to the target context's home directory.
@@ -470,11 +472,20 @@ class Connection(ansible.plugins.connection.ConnectionBase):
         # https://github.com/dw/mitogen/issues/140
         self.close()
 
-    def on_action_run(self, task_vars, loader_basedir):
+    def on_action_run(self, task_vars, delegate_to_hostname, loader_basedir):
         """
         Invoked by ActionModuleMixin to indicate a new task is about to start
         executing. We use the opportunity to grab relevant bits from the
         task-specific data.
+
+        :param dict task_vars:
+            Task variable dictionary.
+        :param str delegate_to_hostname:
+            :data:`None`, or the template-expanded inventory hostname this task
+            is being delegated to. A similar variable exists on PlayContext
+            when ``delegate_to:`` is active, however it is unexpanded.
+        :param str loader_basedir:
+            Loader base directory; see :attr:`loader_basedir`.
         """
         self.ansible_ssh_timeout = task_vars.get('ansible_ssh_timeout',
                                                  C.DEFAULT_TIMEOUT)
@@ -488,6 +499,7 @@ class Connection(ansible.plugins.connection.ConnectionBase):
         self.mitogen_ssh_debug_level = task_vars.get('mitogen_ssh_debug_level')
         self.inventory_hostname = task_vars['inventory_hostname']
         self.host_vars = task_vars['hostvars']
+        self.delegate_to_hostname = delegate_to_hostname
         self.loader_basedir = loader_basedir
         self.close(new_task=True)
 
@@ -563,6 +575,26 @@ class Connection(ansible.plugins.connection.ConnectionBase):
                 broker=self.broker,
             )
 
+    def _config_from_direct_connection(self):
+        """
+        """
+        return config_from_play_context(
+            transport=self.transport,
+            inventory_name=self.inventory_hostname,
+            connection=self
+        )
+
+    def _config_from_delegate_to(self):
+        return config_from_hostvars(
+            transport=self._play_context.connection,
+            inventory_name=self.delegate_to_hostname,
+            connection=self,
+            hostvars=self.host_vars[self._play_context.delegate_to],
+            become_user=(self._play_context.become_user
+                         if self._play_context.become
+                         else None),
+        )
+
     def _build_stack(self):
         """
         Construct a list of dictionaries representing the connection
@@ -570,22 +602,11 @@ class Connection(ansible.plugins.connection.ConnectionBase):
         additionally used by the integration tests "mitogen_get_stack" action
         to fetch the would-be connection configuration.
         """
-        if hasattr(self._play_context, 'delegate_to'):
-            target_config = config_from_hostvars(
-                transport=self._play_context.connection,
-                inventory_name=self._play_context.delegate_to,
-                connection=self,
-                hostvars=self.host_vars[self._play_context.delegate_to],
-                become_user=(self._play_context.become_user
-                             if self._play_context.become
-                             else None),
-            )
+        if self.delegate_to_hostname is not None:
+            target_config = self._config_from_delegate_to()
         else:
-            target_config = config_from_play_context(
-                transport=self.transport,
-                inventory_name=self.inventory_hostname,
-                connection=self
-            )
+            target_config = self._config_from_direct_connection()
+
         stack, _ = self._stack_from_config(target_config)
         return stack
 

ansible_mitogen/mixins.py

@@ -110,6 +110,7 @@ class ActionModuleMixin(ansible.plugins.action.ActionBase):
         """
         self._connection.on_action_run(
             task_vars=task_vars,
+            delegate_to_hostname=self._task.delegate_to,
             loader_basedir=self._loader.get_basedir(),
         )
         return super(ActionModuleMixin, self).run(tmp, task_vars)

tests/ansible/integration/delegation/all.yml

@@ -1,2 +1,2 @@
-
+- import_playbook: delegate_to_template.yml
 - import_playbook: stack_construction.yml

tests/ansible/integration/delegation/delegate_to_template.yml

@@ -0,0 +1,41 @@
+# Ensure templated delegate_to field works.
+
+- name: integration/delegation/delegate_to_template.yml
+  vars:
+    physical_host: "cd-normal-alias"
+    physical_hosts: ["cd-normal-alias", "cd-normal-normal"]
+  hosts: test-targets
+  gather_facts: no
+  any_errors_fatal: true
+  tasks:
+    - mitogen_get_stack:
+      delegate_to: "{{ physical_host }}"
+      register: out
+
+    - assert:
+        that: |
+          out.result == [
+            {
+                'kwargs': {
+                    'check_host_keys': 'ignore',
+                    'connect_timeout': 10,
+                    'hostname': 'cd-normal-alias',
+                    'identity_file': None,
+                    'password': None,
+                    'port': None,
+                    'python_path': None,
+                    'ssh_args': [
+                        '-o',
+                        'ForwardAgent=yes',
+                        '-o',
+                        'ControlMaster=auto',
+                        '-o',
+                        'ControlPersist=60s',
+                    ],
+                    'ssh_debug_level': None,
+                    'ssh_path': 'ssh',
+                    'username': None,
+                },
+                'method': 'ssh',
+            },
+          ]