Handle top-level vars for include tasks to match v1 syntax

The "streamlined" syntax will be deprecated at some point in the future.

Fixes #11882

lib/ansible/playbook/base.py

@@ -65,6 +65,13 @@ class Base:
         # and initialize the base attributes
         self._initialize_base_attributes()
 
+        try:
+            from __main__ import display
+            self._display = display
+        except ImportError:
+            from ansible.utils.display import Display
+            self._display = Display()
+
     # The following three functions are used to programatically define data
     # descriptors (aka properties) for the Attributes of all of the playbook
     # objects (tasks, blocks, plays, etc).

lib/ansible/playbook/task.py

@@ -162,6 +162,16 @@ class Task(Base, Conditional, Taggable, Become):
         new_ds['args']        = args
         new_ds['delegate_to'] = delegate_to
 
+        # we handle any 'vars' specified in the ds here, as we may
+        # be adding things to them below (special handling for includes).
+        # When that deprecated feature is removed, this can be too.
+        if 'vars' in ds:
+            if not isinstance(ds['vars'], dict):
+                raise AnsibleError("vars specified on a task must be a dictionary (got a %s)" % type(ds['vars']), obj=new_ds)
+            new_ds['vars'] = ds.pop('vars')
+        else:
+            new_ds['vars'] = dict()
+
         for (k,v) in ds.iteritems():
             if k in ('action', 'local_action', 'args', 'delegate_to') or k == action or k == 'shell':
                 # we don't want to re-assign these values, which were
@@ -170,7 +180,15 @@ class Task(Base, Conditional, Taggable, Become):
             elif k.replace("with_", "") in lookup_loader:
                 self._preprocess_loop(ds, new_ds, k, v)
             else:
-                new_ds[k] = v
+                # pre-2.0 syntax allowed variables for include statements at the
+                # top level of the task, so we move those into the 'vars' dictionary
+                # here, and show a deprecation message as we will remove this at
+                # some point in the future.
+                if action == 'include' and k not in self._get_base_attributes():
+                    self._display.deprecated("Specifying include variables at the top-level of the task is deprecated. Please see:\nhttp://docs.ansible.com/ansible/playbooks_roles.html#task-include-files-and-encouraging-reuse\n\nfor currently supported syntax regarding included files and variables")
+                    new_ds['vars'][k] = v
+                else:
+                    new_ds[k] = v
 
         return super(Task, self).preprocess_data(new_ds)