Use a sentinel to indicate when all attributes are required

To generate its NodeData, a Resource must know which of its attributes
other parts of the template have dependencies on, which it determines by
asking the intrinsic functions in the template. Currently, the get_attr
function when used with no arguments depends on all of the attributes of
the resource (except 'show'), and it obtains this list from the Resource
itself (via the attributes_schema). This presents a chicken-and-egg problem
if we want to give Functions access only to a ResourceProxy based on the
NodeData.

Resolve this by returning a constant sentinel value (indicating that all
attributes are required) to the Resource, which can determine for itself
what attributes it has.

Change-Id: If209b589278fe1facb06e157fe76209fdd42a8a2
Partially-Implements: blueprint stack-definition

heat/engine/attributes.py

@@ -135,6 +135,10 @@ def _stack_id_output(resource_name, template_type='cfn'):
 
 BASE_ATTRIBUTES = (SHOW_ATTR, ) = ('show', )
 
+# Returned by function.dep_attrs() to indicate that all attributes are
+# referenced
+ALL_ATTRIBUTES = '*'
+
 
 @repr_wrapper
 class Attributes(collections.Mapping):
@@ -146,6 +150,9 @@ class Attributes(collections.Mapping):
         self._attributes = Attributes._make_attributes(schema)
         self.reset_resolved_values()
 
+        assert ALL_ATTRIBUTES not in schema, \
+            "Invalid attribute name '%s'" % ALL_ATTRIBUTES
+
     def reset_resolved_values(self):
         self._resolved_values = {}
 

heat/engine/function.py

@@ -73,6 +73,9 @@ class Function(object):
 
         Return an iterator over any attributes of the specified resource that
         this function references.
+
+        The special value heat.engine.attributes.ALL_ATTRIBUTES may be used to
+        indicate that all attributes of the resource are required.
         """
         return dep_attrs(self.args, resource_name)
 
@@ -179,6 +182,9 @@ class Macro(Function):
 
         Return an iterator over any attributes of the specified resource that
         this function references.
+
+        The special value heat.engine.attributes.ALL_ATTRIBUTES may be used to
+        indicate that all attributes of the resource are required.
         """
         return dep_attrs(self.parsed, resource_name)
 

heat/engine/hot/functions.py

@@ -315,8 +315,7 @@ class GetAttAllAttributes(GetAtt):
         if self._attribute is not None:
             return super(GetAttAllAttributes, self).dep_attrs(resource_name)
         elif self._res_name() == resource_name:
-            res = self._resource()
-            attrs = six.iterkeys(res.attributes_schema)
+            attrs = [attributes.ALL_ATTRIBUTES]
         else:
             attrs = []
         return itertools.chain(function.dep_attrs(self.args,

heat/engine/resource.py

@@ -872,9 +872,13 @@ class Resource(status.ResourceStatus):
                 except exception.InvalidTemplateAttribute as ita:
                     LOG.info('%s', ita)
 
-        dep_attrs = self.stack.get_dep_attrs(
+        dep_attrs = set(self.stack.get_dep_attrs(
             six.itervalues(self.stack.resources),
-            self.name)
+            self.name))
+        if attributes.ALL_ATTRIBUTES in dep_attrs:
+            dep_attrs.remove(attributes.ALL_ATTRIBUTES)
+            dep_attrs |= (set(self.attributes) - {self.SHOW})
+
         return node_data.NodeData(self.id, self.name, self.uuid,
                                   self.get_reference_id(),
                                   dict(get_attrs(dep_attrs)),