Allow function 'yaql' as condition function

Allow 'yaql' in condition definition, like:

parameters:
  ServiceNames:
    type: comma_delimited_list
    default: ['neutron', 'heat']
conditions:
  contains_neutron:
    yaql:
      expression: $.data.service_names.contains('neutron')
      data:
        service_names:
          get_param: ServiceNames

Closes-Bug: #1693093

Change-Id: I83a540336c01a696780621fb2b39486a6abf0917

doc/source/template_guide/hot_spec.rst

@@ -321,6 +321,7 @@ for the ``heat_template_version`` key:
       yaql
       if
 
+    We support 'yaql' as condition function in this version.
     The complete list of supported condition functions is::
 
       equals
@@ -328,6 +329,7 @@ for the ``heat_template_version`` key:
       not
       and
       or
+      yaql
 
 .. _hot_spec_parameter_groups:
 
@@ -934,10 +936,12 @@ expression
       not
       and
       or
+      yaql
 
     Note: In condition functions, you can reference a value from an input
     parameter, but you cannot reference resource or its attribute. We support
     referencing other conditions (by condition name) in condition functions.
+    We support 'yaql' as condition function in the Pike version.
 
 An example of conditions section definition
 
@@ -979,6 +983,12 @@ An example of conditions section definition
        and:
        - cd1
        - cd2
+     cd9:
+       yaql:
+         expression: $.data.services.contains('heat')
+         data:
+           services:
+             get_param: ServiceNames
 
 The example below shows how to associate condition with resources
 

heat/engine/hot/template.py

@@ -607,3 +607,14 @@ class HOTemplate20170901(HOTemplate20170224):
         'Fn::ResourceFacade': hot_funcs.Removed,
         'Ref': hot_funcs.Removed,
     }
+
+    condition_functions = {
+        'get_param': hot_funcs.GetParam,
+        'equals': hot_funcs.Equals,
+        'not': hot_funcs.Not,
+        'and': hot_funcs.And,
+        'or': hot_funcs.Or,
+
+        # functions added in 2017-09-01
+        'yaql': hot_funcs.Yaql
+    }

heat/tests/test_hot.py

@@ -1299,6 +1299,36 @@ class HOTemplateTest(common.HeatTestCase):
 
         self.assertEqual({'a': [1, 2, 3]}, resolved)
 
+    def test_yaql_as_condition(self):
+        hot_tpl = template_format.parse('''
+        heat_template_version: pike
+        parameters:
+          ServiceNames:
+            type: comma_delimited_list
+            default: ['neutron', 'heat']
+        ''')
+        snippet = {
+            'yaql': {
+                'expression': '$.data.service_names.contains("neutron")',
+                'data': {'service_names': {'get_param': 'ServiceNames'}}}}
+        # when param 'ServiceNames' contains 'neutron',
+        # equals function resolve to true
+        tmpl = template.Template(hot_tpl)
+        stack = parser.Stack(utils.dummy_context(),
+                             'test_condition_yaql_true', tmpl)
+        resolved = self.resolve_condition(snippet, tmpl, stack)
+        self.assertTrue(resolved)
+        # when param 'ServiceNames' doesn't contain 'neutron',
+        # equals function resolve to false
+        tmpl = template.Template(
+            hot_tpl,
+            env=environment.Environment(
+                {'ServiceNames': ['nova_network', 'heat']}))
+        stack = parser.Stack(utils.dummy_context(),
+                             'test_condition_yaql_false', tmpl)
+        resolved = self.resolve_condition(snippet, tmpl, stack)
+        self.assertFalse(resolved)
+
     def test_equals(self):
         hot_tpl = template_format.parse('''
         heat_template_version: 2016-10-14