Allowing `args: "{{some_var}}"` for task params again

This is unsafe and we debated re-adding it to the v2/2.0 codebase,
however it is a common-enough feature that we will simply mark it
as deprecated for now and remove it at some point in the future.

Fixes #11718

lib/ansible/executor/task_executor.py

@@ -60,6 +60,13 @@ class TaskExecutor:
         self._loader            = loader
         self._shared_loader_obj = shared_loader_obj
 
+        try:
+            from __main__ import display
+            self._display = display
+        except ImportError:
+            from ansible.utils.display import Display
+            self._display = Display()
+
     def run(self):
         '''
         The main executor entrypoint, where we determine if the specified
@@ -229,6 +236,12 @@ class TaskExecutor:
             prev_var = self._task.args.pop('var')
 
         self._task.post_validate(templar=templar)
+        if '_variable_params' in self._task.args:
+            variable_params = self._task.args.pop('_variable_params')
+            if isinstance(variable_params, dict):
+                self._display.deprecated("Using variables for task params is unsafe, especially if the variables come from an external source like facts")
+                variable_params.update(self._task.args)
+                self._task.args = variable_params
 
         if prev_var is not None:
             self._task.args['var'] = prev_var

lib/ansible/parsing/mod_args.py

@@ -24,6 +24,7 @@ from six import iteritems, string_types
 from ansible.errors import AnsibleParserError
 from ansible.plugins import module_loader
 from ansible.parsing.splitter import parse_kv, split_args
+from ansible.template import Templar
 
 # For filtering out modules correctly below
 RAW_PARAM_MODULES = ([
@@ -278,7 +279,12 @@ class ModuleArgsParser:
         if action is None:
             raise AnsibleParserError("no action detected in task", obj=self._task_ds)
         elif args.get('_raw_params', '') != '' and action not in RAW_PARAM_MODULES:
-            raise AnsibleParserError("this task '%s' has extra params, which is only allowed in the following modules: %s" % (action, ", ".join(RAW_PARAM_MODULES)), obj=self._task_ds)
+            templar = Templar(loader=None)
+            raw_params = args.pop('_raw_params')
+            if templar._contains_vars(raw_params):
+                args['_variable_params'] = raw_params
+            else:
+                raise AnsibleParserError("this task '%s' has extra params, which is only allowed in the following modules: %s" % (action, ", ".join(RAW_PARAM_MODULES)), obj=self._task_ds)
 
         # shell modules require special handling
         (action, args) = self._handle_shell_weirdness(action, args)

lib/ansible/template/__init__.py

@@ -56,10 +56,14 @@ class Templar:
 
     def __init__(self, loader, shared_loader_obj=None, variables=dict()):
         self._loader              = loader
-        self._basedir             = loader.get_basedir()
         self._filters             = None
         self._available_variables = variables
 
+        if loader:
+            self._basedir = loader.get_basedir()
+        else:
+            self._basedir = './'
+
         if shared_loader_obj:
             global _basedirs
             _basedirs = shared_loader_obj.basedirs[:]

lib/ansible/utils/display.py

@@ -130,9 +130,9 @@ class Display:
 
         if not removed:
             if version:
-                new_msg = "\n[DEPRECATION WARNING]: %s. This feature will be removed in version %s." % (msg, version)
+                new_msg = "[DEPRECATION WARNING]: %s. This feature will be removed in version %s." % (msg, version)
             else:
-                new_msg = "\n[DEPRECATION WARNING]: %s. This feature will be removed in a future release." % (msg)
+                new_msg = "[DEPRECATION WARNING]: %s. This feature will be removed in a future release." % (msg)
             new_msg = new_msg + " Deprecation warnings can be disabled by setting deprecation_warnings=False in ansible.cfg.\n\n"
         else:
             raise AnsibleError("[DEPRECATED]: %s.  Please update your playbooks." % msg)