Remove six and python 2.7 full support

Six is in use to help us to keep support for python 2.7.
Since the ussuri cycle we decide to remove the python 2.7
support so we can go ahead and also remove six usage from
the python code.

Review process and help
-----------------------
Removing six introduce a lot of changes and an huge amount of modified files
To simplify reviews we decided to split changes into several patches to avoid
painful reviews and avoid mistakes.

To review this patch you can use the six documentation [1] to obtain help and
understand choices.

Additional informations
-----------------------
Changes related to 'six.b(data)' [2]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

six.b [2] encode the given datas in latin-1 in python3 so I did the same
things in this patch.

Latin-1 is equal to iso-8859-1 [3].

This encoding is the default encoding [4] of certain descriptive HTTP
headers.

I suggest to keep latin-1 for the moment and to move to another encoding
in a follow-up patch if needed to move to most powerful encoding (utf8).

HTML4 support utf8 charset and utf8 is the default charset for HTML5 [5].

Note that this commit message is autogenerated and not necesserly contains
changes related to 'six.b'

[1] https://six.readthedocs.io/
[2] https://six.readthedocs.io/#six.b
[3] https://docs.python.org/3/library/codecs.html#standard-encodings
[4] https://www.w3schools.com/charsets/ref_html_8859.asp
[5] https://www.w3schools.com/html/html_charset.asp

Patch 14 of a serie of 28 patches

Change-Id: Iccb743056c631f2e0728013942d764cd8b1ecfe0

3 files changed, 8 insertions, 11 deletions

diff --git a/heat/objects/fields.py b/heat/objects/fields.py
index 88290150d..19680f6d9 100644
--- a/heat/objects/fields.py
+++ b/heat/objects/fields.py
@@ -15,12 +15,11 @@
 
 from oslo_serialization import jsonutils as json
 from oslo_versionedobjects import fields
-import six
 
 
 class Json(fields.FieldType):
     def coerce(self, obj, attr, value):
-        if isinstance(value, six.string_types):
+        if isinstance(value, str):
             loaded = json.loads(value)
             return loaded
         return value
diff --git a/heat/objects/resource.py b/heat/objects/resource.py
index 3aba3405f..ecb38c97c 100644
--- a/heat/objects/resource.py
+++ b/heat/objects/resource.py
@@ -21,7 +21,6 @@ from oslo_config import cfg
 from oslo_log import log as logging
 from oslo_versionedobjects import base
 from oslo_versionedobjects import fields
-import six
 import tenacity
 
 from heat.common import crypt
@@ -57,7 +56,7 @@ class ResourceCache(object):
         self.by_stack_id_name = collections.defaultdict(dict)
 
     def set_by_stack_id(self, resources):
-        for res in six.itervalues(resources):
+        for res in resources.values():
             self.by_stack_id_name[res.stack_id][res.name] = res
 
 
@@ -190,7 +189,7 @@ class Resource(
                 resource_name,
                 cls._from_db_object(cls(context), context, resource_db)
             )
-            for resource_name, resource_db in six.iteritems(resources_db)
+            for resource_name, resource_db in resources_db.items()
         ]
         return dict(resources)
 
@@ -246,7 +245,7 @@ class Resource(
                 resource_name,
                 cls._from_db_object(cls(context), context, resource_db)
             )
-            for resource_name, resource_db in six.iteritems(resources_db)
+            for resource_name, resource_db in resources_db.items()
         ]
         return dict(resources)
 
@@ -259,7 +258,7 @@ class Resource(
                 resource_id,
                 cls._from_db_object(cls(context), context, resource_db)
             )
-            for resource_id, resource_db in six.iteritems(resources_db)
+            for resource_id, resource_db in resources_db.items()
         ]
         return dict(resources)
 
@@ -280,7 +279,7 @@ class Resource(
             context,
             stack_id,
             stack_id_only=True)
-        return {db_res.stack_id for db_res in six.itervalues(resources_db)}
+        return {db_res.stack_id for db_res in resources_db.values()}
 
     @classmethod
     def purge_deleted(cls, context, stack_id):
diff --git a/heat/objects/stack.py b/heat/objects/stack.py
index a6904865d..349aaada8 100644
--- a/heat/objects/stack.py
+++ b/heat/objects/stack.py
@@ -18,7 +18,6 @@
 from oslo_log import log as logging
 from oslo_versionedobjects import base
 from oslo_versionedobjects import fields
-import six
 
 from heat.common import exception
 from heat.common.i18n import _
@@ -117,7 +116,7 @@ class Stack(
     def get_by_name_and_owner_id(cls, context, stack_name, owner_id):
         db_stack = db_api.stack_get_by_name_and_owner_id(
             context,
-            six.text_type(stack_name),
+            str(stack_name),
             owner_id
         )
         if not db_stack:
@@ -127,7 +126,7 @@ class Stack(
 
     @classmethod
     def get_by_name(cls, context, stack_name):
-        db_stack = db_api.stack_get_by_name(context, six.text_type(stack_name))
+        db_stack = db_api.stack_get_by_name(context, str(stack_name))
         if not db_stack:
             return None
         stack = cls._from_db_object(context, cls(context), db_stack)