Support delegation in strategy plugin

The strategy plugin previously did not support container detection
when the delegate_to host was a container. This adds support for
delegating tasks to other containers, so the strategy will perform
the same container vars lookups so the SSH connection is toward the
physical host of the container, and the command is wrapped with
lxc-attach based on the container_name.

Co-Authored-By: Jimmy McCrory <jimmy.mccrory@gmail.com>
Change-Id: I56d8afddbccf01f2944d2fdd505b601a4b048374

connection/ssh.py

@@ -46,11 +46,18 @@ class Connection(SSH.Connection):
         super(Connection, self).__init__(*args, **kwargs)
         self.args = args
         self.kwargs = kwargs
-        self.vars = self._play_context._attributes['vars']
+        if hasattr(self._play_context, 'chroot_path'):
-        self.chroot_path = self.vars.get('chroot_path')
+            self.chroot_path = self._play_context.chroot_path
-        self.container_name = self.vars.get('container_name')
+        else:
-        self.physical_host = self.vars.get('physical_host')
+            self.chroot_path = None
-        self.physical_hostname = self.vars.get('physical_hostname')
+        if hasattr(self._play_context, 'container_name'):
+            self.container_name = self._play_context.container_name
+        else:
+            self.container_name = None
+        if hasattr(self._play_context, 'physical_host'):
+            self.physical_host = self._play_context.physical_host
+        else:
+            self.physical_host = None
         if self._container_check() or self._chroot_check():
             self.host = self._play_context.remote_addr = self.physical_host
 
@@ -68,11 +75,11 @@ class Connection(SSH.Connection):
         return super(Connection, self).exec_command(cmd, in_data, sudoable)
 
     def _chroot_check(self):
-        if self.chroot_path:
+        if self.chroot_path is not None:
             SSH.display.vvv(u'chroot_path: "%s"' % self.chroot_path)
-            if self.physical_hostname:
+            if self.physical_host is not None:
                 SSH.display.vvv(
-                    u'physical_hostname: "%s"' % self.physical_hostname
+                    u'physical_host: "%s"' % self.physical_host
                 )
                 SSH.display.vvv(u'chroot confirmed')
                 return True
@@ -80,13 +87,13 @@ class Connection(SSH.Connection):
         return False
 
     def _container_check(self):
-        if self.container_name:
+        if self.container_name is not None:
             SSH.display.vvv(u'container_name: "%s"' % self.container_name)
-            if self.physical_hostname:
+            if self.physical_host is not None:
                 SSH.display.vvv(
-                    u'physical_hostname: "%s"' % self.physical_hostname
+                    u'physical_host: "%s"' % self.physical_host
                 )
-                if self.container_name != self.physical_hostname:
+                if self.container_name != self.physical_host:
                     SSH.display.vvv(u'Container confirmed')
                     return True
 

strategy/linear.py

@@ -26,6 +26,16 @@ LINEAR = imp.load_source(
     os.path.join(os.path.dirname(strategy.__file__), 'linear.py')
 )
 
+# NOTICE(jmccrory): The play_context is imported so that additional container
+#                   specific variables can be made available to connection
+#                   plugins.
+import ansible.playbook.play_context
+ansible.playbook.play_context.MAGIC_VARIABLE_MAPPING.update({'physical_host':
+                                                           ('physical_host',)})
+ansible.playbook.play_context.MAGIC_VARIABLE_MAPPING.update({'container_name':
+                                                           ('inventory_hostname',)})
+ansible.playbook.play_context.MAGIC_VARIABLE_MAPPING.update({'chroot_path':
+                                                           ('chroot_path',)})
 
 class StrategyModule(LINEAR.StrategyModule):
     """Notes about this strategy.
@@ -94,15 +104,14 @@ class StrategyModule(LINEAR.StrategyModule):
     def _queue_task(self, host, task, task_vars, play_context):
         """Queue a task to be sent to the worker.
 
-        Modify the playbook_context to support adding attributes for remote
+        Modify the playbook_context to disable pipelining and use the paramiko
-        LXC containers or remote chroots.
+        transport method when a task is being delegated.
         """
         templar = LINEAR.Templar(loader=self._loader, variables=task_vars)
         if not self._check_when(host, task, templar, task_vars):
             return
 
         _play_context = copy.deepcopy(play_context)
-        _vars = _play_context._attributes['vars']
         if task.delegate_to:
             # If a task uses delegation change the play_context
             #  to use paramiko with pipelining disabled for this
@@ -129,30 +138,6 @@ class StrategyModule(LINEAR.StrategyModule):
                     host=host,
                     caplevel=0
                 )
-        else:
-            physical_host = _vars.get('physical_host')
-            if not physical_host:
-                physical_host = task_vars.get('physical_host')
-                if physical_host:
-                    ph = self._inventory.get_host(physical_host)
-                    ansible_host = ph.vars.get('ansible_host')
-                    if not ansible_host:
-                        ansible_host = ph.vars.get('ansible_host')
-                    if ansible_host:
-                        _vars['physical_host'] = ansible_host
-                        _vars['physical_hostname'] = physical_host
-
-            container_name = _vars.get('container_name')
-            if not container_name:
-                container_name = task_vars.get('container_name')
-                if container_name:
-                    _vars['container_name'] = container_name
-
-            chroot_path = _vars.get('chroot_path')
-            if not chroot_path:
-                chroot_path = task_vars.get('chroot_path')
-                if chroot_path:
-                    _vars['chroot_path'] = chroot_path
 
         return super(StrategyModule, self)._queue_task(
             host,