Allow Resources to select paths from attributes

Previously when get_attr included a path to select from the attribute, the
selection was done by the get_attr intrinsic function. Starting with the
Juno version of HOT, move control of this to the resource plugin, so that
individual resources (particularly ResourceGroup) can handle it themselves.

Related-Bug: #1341048
Change-Id: Ic3dc94a99a19e28a4f775198ff6e960e2efb8256

1 files changed, 29 insertions, 3 deletions

diff --git a/heat/engine/hot/functions.py b/heat/engine/hot/functions.py
index 84bd05aab..23c333bb7 100644
--- a/heat/engine/hot/functions.py
+++ b/heat/engine/hot/functions.py
@@ -83,7 +83,7 @@ class GetParam(function.Function):
             return ''
 
 
-class GetAtt(cfn_funcs.GetAtt):
+class GetAttThenSelect(cfn_funcs.GetAtt):
     '''
     A function for resolving resource attributes.
 
@@ -112,7 +112,7 @@ class GetAtt(cfn_funcs.GetAtt):
         return tuple(self.args[:2])
 
     def result(self):
-        attribute = super(GetAtt, self).result()
+        attribute = super(GetAttThenSelect, self).result()
         if attribute is None:
             return None
 
@@ -120,6 +120,32 @@ class GetAtt(cfn_funcs.GetAtt):
         return attributes.select_from_attribute(attribute, path_components)
 
 
+class GetAtt(GetAttThenSelect):
+    '''
+    A function for resolving resource attributes.
+
+    Takes the form::
+
+        get_attr:
+          - <resource_name>
+          - <attribute_name>
+          - <path1>
+          - ...
+    '''
+
+    def result(self):
+        path_components = function.resolve(self._path_components)
+        attribute = function.resolve(self._attribute)
+
+        r = self._resource()
+        if (r.status in (r.IN_PROGRESS, r.COMPLETE) and
+                r.action in (r.CREATE, r.ADOPT, r.SUSPEND, r.RESUME,
+                             r.UPDATE)):
+            return r.FnGetAtt(attribute, *path_components)
+        else:
+            return None
+
+
 class Replace(cfn_funcs.Replace):
     '''
     A function for performing string substitutions.
@@ -247,7 +273,7 @@ def function_mapping(version_key, version):
             'get_param': GetParam,
             'get_resource': cfn_funcs.ResourceRef,
             'Ref': cfn_funcs.Ref,
-            'get_attr': GetAtt,
+            'get_attr': GetAttThenSelect,
             'Fn::Select': cfn_funcs.Select,
             'Fn::Join': cfn_funcs.Join,
             'Fn::Split': cfn_funcs.Split,