add static facility and apply to register (#49737)

* add static facility and apply to register

* added warning

* added test for templated register

* test register 'static' status

* rely on subshell to deal with quote context

* use corrects pb for test

* bring constants back cause new code in devel

changelogs/fragments/static_attributes.yml

@@ -0,0 +1,2 @@
+minor_changes:
+    - add facility for playbook attributes that are not templatable, i.e register

lib/ansible/playbook/attribute.py

@@ -41,6 +41,7 @@ class Attribute:
         alias=None,
         extend=False,
         prepend=False,
+        static=False,
     ):
 
         """
@@ -86,6 +87,7 @@ class Attribute:
         self.alias = alias
         self.extend = extend
         self.prepend = prepend
+        self.static = static
 
         if default is not None and self.isa in _CONTAINERS and not callable(default):
             raise TypeError('defaults for FieldAttribute may not be mutable, please provide a callable instead')

lib/ansible/playbook/base.py

@@ -14,6 +14,7 @@ from functools import partial
 from jinja2.exceptions import UndefinedError
 
 from ansible import constants as C
+
 from ansible.module_utils.six import iteritems, string_types, with_metaclass
 from ansible.module_utils.parsing.convert_bool import boolean
 from ansible.errors import AnsibleParserError, AnsibleUndefinedVariable, AnsibleAssertionError
@@ -350,6 +351,13 @@ class FieldAttributeBase(with_metaclass(BaseMeta, object)):
 
         for (name, attribute) in iteritems(self._valid_attrs):
 
+            if attribute.static:
+                value = getattr(self, name)
+                if templar.is_template(value):
+                    display.warning('"%s" is not templatable, but we found: %s, '
+                                    'it will not be templated and will be used "as is".' % (name, value))
+                continue
+
             if getattr(self, name) is None:
                 if not attribute.required:
                     continue

lib/ansible/playbook/task.py

@@ -80,7 +80,7 @@ class Task(Base, Conditional, Taggable, Become):
     _loop_control = FieldAttribute(isa='class', class_type=LoopControl, inherit=False)
     _notify = FieldAttribute(isa='list')
     _poll = FieldAttribute(isa='int', default=10)
-    _register = FieldAttribute(isa='string')
+    _register = FieldAttribute(isa='string', static=True)
     _retries = FieldAttribute(isa='int', default=3)
     _until = FieldAttribute(isa='list', default=list)
 

test/integration/targets/templating_settings/dont_warn_register.yml

@@ -0,0 +1,6 @@
+- hosts: testhost
+  gather_facts: false
+  tasks:
+    - name: template in register warns, but no template should not
+      debug: msg=unimportant
+      register: thisshouldnotwarn

test/integration/targets/templating_settings/runme.sh

@@ -3,3 +3,5 @@
 set -eux
 
 ansible-playbook test_templating_settings.yml -i ../../inventory -v "$@"
+ansible-playbook warn_on_register.yml -i ../../inventory -v "$@" 2>&1| grep 'is not templatable, but we found'
+[ "$(ansible-playbook dont_warn_register.yml -i ../../inventory -v "$@" 2>&1| grep -c 'is not templatable, but we found')" == "0" ]

test/integration/targets/templating_settings/warn_on_register.yml

@@ -0,0 +1,8 @@
+- hosts: testhost
+  gather_facts: false
+  vars:
+    thisshouldwarn: noreally
+  tasks:
+    - name: template in register warns
+      debug: msg=unimportant
+      register: '{{ thisshouldwarn }}'