Added yaml class dumper to support indentation

The default py yaml `safe_dumps` keeps to the yaml spec which states
incremental indentations are not required. Sadly, without the
indentations some consumers of yaml configurations files will break.
This commit adds an incremental indentation dumper to cater for all
yaml configuration consumers.

Change-Id: Ifa5bcc6ff9f0a9cb5e619e62d0356f5d6887ca6e
Signed-off-by: Kevin Carter <kevin.carter@rackspace.com>

action/_v2_config_template.py

@@ -73,6 +73,11 @@ def _convert_2_string(item):
             return str(item)
 
 
+class IDumper(yaml.SafeDumper):
+    def increase_indent(self, flow=False, indentless=False):
+        return super(IDumper, self).increase_indent(flow, False)
+
+
 class MultiKeyDict(dict):
     """Dictionary class which supports duplicate keys.
     This class allows for an item to be added into a standard python dictionary
@@ -374,8 +379,9 @@ class ActionModule(ActionBase):
             new_items=config_overrides,
             list_extend=list_extend
         )
-        return yaml.safe_dump(
+        return yaml.dump(
             merged_resultant,
+            Dumper=IDumper,
             default_flow_style=False,
             width=1000,
         )

tests/files/test_extend.yml.expected

@@ -1,8 +1,8 @@
 list_one:
-- one
-- two
-- three
-- four
+  - one
+  - two
+  - three
+  - four
 list_two:
-- one
-- two
+  - one
+  - two

tests/files/test_no_extend.yml.expected

@@ -1,5 +1,5 @@
 list_one:
-- four
+  - four
 list_two:
-- one
-- two
+  - one
+  - two