1 files changed, 51 insertions, 22 deletions
diff --git a/cloudinit/mergers/m_dict.py b/cloudinit/mergers/m_dict.py
index 929d3865..2c1c845f 100644
--- a/cloudinit/mergers/m_dict.py
+++ b/cloudinit/mergers/m_dict.py
@@ -20,30 +20,59 @@
 class Merger(object):
     def __init__(self, merger, opts):
         self._merger = merger
-        self._not_overwrite = 'not_overwrite' in opts
+        # Affects merging behavior...
+        self._method = 'replace'
+        for m in ['replace', 'no_replace']:
+            if m in opts:
+                self._method = m
+                break
+        # Affect how recursive merging is done on other primitives
+        self._recurse_str = 'recurse_str' in opts
+        self._recurse_dict = True
+        self._recurse_array = 'recurse_array' in opts
+        self._allow_delete = 'allow_delete' in opts
+
+    def __str__(self):
+        s = ('DictMerger: (method=%s,recurse_str=%s,'
+             'recurse_dict=%s,recurse_array=%s,allow_delete=%s)')
+        s  = s % (self._method,
+                  self._recurse_str,
+                  self._recurse_dict,
+                  self._recurse_array,
+                  self._allow_delete)
+        return s
+
+    def _do_dict_replace(self, value, merge_with, do_replace=True):
+
+        def merge_same_key(old_v, new_v):
+            if do_replace:
+                return new_v
+            if isinstance(new_v, (list, tuple)) and self._recurse_array:
+                return self._merger.merge(old_v, new_v)
+            if isinstance(new_v, (str, basestring)) and self._recurse_str:
+                return self._merger.merge(old_v, new_v)
+            if isinstance(new_v, (dict)) and self._recurse_dict:
+                return self._merger.merge(old_v, new_v)
+            # Otherwise leave it be...
+            return old_v
 
-    # This merging algorithm will attempt to merge with
-    # another dictionary, on encountering any other type of object
-    # it will not merge with said object, but will instead return
-    # the original value
-    #
-    # On encountering a dictionary, it will create a new dictionary
-    # composed of the original and the one to merge with, if 'overwrite'
-    # is enabled then keys that exist in the original will be overwritten
-    # by keys in the one to merge with (and associated values). Otherwise
-    # if not in overwrite mode the 2 conflicting keys themselves will
-    # be merged.
-    def _on_dict(self, value, merge_with):
-        if not isinstance(merge_with, (dict)):
-            return value
-        merged = dict(value)
         for (k, v) in merge_with.items():
-            if k in merged:
-                if self._not_overwrite:
-                    # Attempt to merge them....
-                    merged[k] = self._merger.merge(merged[k], v)
+            if k in value:
+                if v is None and self._allow_delete:
+                    value.pop(k)
                 else:
-                    merged[k] = v
+                    value[k] = merge_same_key(value[k], v)
             else:
-                merged[k] = v
+                value[k] = v
+        return value
+
+    def _on_dict(self, value, merge_with):
+        if not isinstance(merge_with, (dict)):
+            return value
+        if self._method == 'replace':
+            merged = self._do_dict_replace(dict(value), merge_with)
+        elif self._method == 'no_replace':
+            merged = self._do_dict_replace(dict(value), merge_with, False)
+        else:
+            raise NotImplementedError("Unknown merge type %s" % (self._method))
         return merged