Perform str_replace trying to match longest string first

Purpose is to avoid str_replace from doing partial replace
when a shorter instance of a matching key is found.

Change-Id: I63c13f4eb3b1375cb2df1a34fd4f09561564f400
Co-Authored-By: Zane Bitter <zbitter@redhat.com>
Closes-Bug: 1600209
(cherry picked from commit a2f5b5cb9ae74fb3262948b0cf1c23fc04c4b7cb)

3 files changed, 51 insertions, 7 deletions

diff --git a/heat/engine/cfn/functions.py b/heat/engine/cfn/functions.py
index 4ed1ea4b2..48101d25c 100644
--- a/heat/engine/cfn/functions.py
+++ b/heat/engine/cfn/functions.py
@@ -393,8 +393,9 @@ class Replace(function.Function):
 
         "<value_1> <value_2>"
 
-    This is implemented using python str.replace on each key. The order in
-    which replacements are performed is undefined.
+    This is implemented using python str.replace on each key. Longer keys are
+    substituted before shorter ones, but the order in which replacements are
+    performed is otherwise undefined.
     """
 
     def __init__(self, stack, fn_name, args):
@@ -454,6 +455,9 @@ class Replace(function.Function):
 
             return string.replace(placeholder, six.text_type(value))
 
+        mapping = collections.OrderedDict(sorted(mapping.items(),
+                                                 key=lambda t: len(t[0]),
+                                                 reverse=True))
         return six.moves.reduce(replace, six.iteritems(mapping), template)
 
 
diff --git a/heat/engine/hot/functions.py b/heat/engine/hot/functions.py
index b4ae00655..83e7e9601 100644
--- a/heat/engine/hot/functions.py
+++ b/heat/engine/hot/functions.py
@@ -247,8 +247,9 @@ class Replace(cfn_funcs.Replace):
 
         "<value_1> <value_2>"
 
-    This is implemented using Python's str.replace on each key. The order in
-    which replacements are performed is undefined.
+    This is implemented using python str.replace on each key. Longer keys are
+    substituted before shorter ones, but the order in which replacements are
+    performed is otherwise undefined.
     """
 
     def _parse_args(self):
@@ -274,9 +275,25 @@ class Replace(cfn_funcs.Replace):
 class ReplaceJson(Replace):
     """A function for performing string substitutions.
 
-    Behaves the same as Replace, but tolerates non-string parameter
-    values, e.g map/list - these are serialized as json before doing
-    the string substitution.
+    Takes the form::
+
+        str_replace:
+          template: <key_1> <key_2>
+          params:
+            <key_1>: <value_1>
+            <key_2>: <value_2>
+            ...
+
+    And resolves to::
+
+        "<value_1> <value_2>"
+
+    This is implemented using python str.replace on each key. Longer keys are
+    substituted before shorter ones, but the order in which replacements are
+    performed is otherwise undefined.
+
+    Non-string param values (e.g maps or lists) are serialized as JSON before
+    being substituted in.
     """
 
     def result(self):
@@ -318,6 +335,9 @@ class ReplaceJson(Replace):
 
             return string.replace(placeholder, six.text_type(value))
 
+        mapping = collections.OrderedDict(sorted(mapping.items(),
+                                                 key=lambda t: len(t[0]),
+                                                 reverse=True))
         return six.moves.reduce(replace, six.iteritems(mapping), template)
 
 
diff --git a/heat/tests/test_hot.py b/heat/tests/test_hot.py
index ec606c48f..3a029a12f 100644
--- a/heat/tests/test_hot.py
+++ b/heat/tests/test_hot.py
@@ -562,6 +562,26 @@ class HOTemplateTest(common.HeatTestCase):
 
         self.assertEqual(snippet_resolved, self.resolve(snippet, tmpl))
 
+    def test_str_replace_order(self, tpl=hot_tpl_empty):
+        """Test str_replace function substitution order."""
+
+        snippet = {'str_replace': {'template': '1234567890',
+                                   'params': {'1': 'a',
+                                              '12': 'b',
+                                              '123': 'c',
+                                              '1234': 'd',
+                                              '12345': 'e',
+                                              '123456': 'f',
+                                              '1234567': 'g'}}}
+
+        tmpl = template.Template(tpl)
+
+        self.assertEqual('g890', self.resolve(snippet, tmpl))
+
+    def test_str_replace_liberty_order(self):
+        """Test str_replace function substitution order."""
+        self.test_str_replace_order(hot_liberty_tpl_empty)
+
     def test_str_replace_syntax(self):
         """Test str_replace function syntax.