Switch to ruamel for yaml handling

The Ruamel library has better support for modifying YAML while keeping
things like comments. This updates our yamlutil module to use
ruamel.yaml instead of PyYAML.

Story: 2002908
Task: 22880

Change-Id: I4ac66c9e3e40780b588377c1dfe42511eed231a3
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>

doc/requirements.txt

@@ -7,3 +7,4 @@ icalendar>=3.10  # BSD
 whereto>=0.3.0  # Apache-2.0
 mwclient==0.8.1
 yamlordereddictloader
+ruamel.yaml>=0.15

openstack_releases/cmds/new_release.py

@@ -36,7 +36,7 @@ def get_deliverable_data(series, deliverable):
     deliverable_filename = 'deliverables/%s/%s.yaml' % (
         series, deliverable)
     with open(deliverable_filename, 'r', encoding='utf-8') as f:
-        return yamlutils.loads(f.read())
+        return yamlutils.loads(f)
 
 
 def increment_version(old_version, increment):

openstack_releases/yamlutils.py

@@ -12,120 +12,23 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import collections
-import re
-
-import six
-import yaml
-import yamlordereddictloader
-
-
-_LIKE_A_NUMBER = re.compile('^[0-9]+.[0-9]+$')
-
-
-def _has_newline(data):
-    if "\n" in data or "\r" in data:
-        return True
-    return False
-
-
-class PrettySafeDumper(yaml.dumper.SafeDumper):
-    """Yaml dumper that tries to not alter original formats (too much)."""
-
-    BINARY_ENCODING = 'utf-8'
-
-    def represent_ordereddict(self, data):
-        values = []
-        node = yaml.nodes.MappingNode(
-            'tag:yaml.org,2002:map', values, flow_style=None)
-        for key, value in data.items():
-            key_item = self.represent_data(key)
-            value_item = self.represent_data(value)
-            values.append((key_item, value_item))
-        return node
-
-    def ignore_aliases(self, data):
-        # Never output alias references; always repeat the data.
-        return True
-
-    def represent_bool(self, data):
-        if data:
-            value = 'yes'
-        else:
-            value = 'no'
-        return self.represent_scalar('tag:yaml.org,2002:bool', value)
-
-    def choose_scalar_style(self):
-        # Avoid messing up dict keys...
-        if self.states[-1] == self.expect_block_mapping_simple_value:
-            self.event.style = 'plain'
-        return super(PrettySafeDumper, self).choose_scalar_style()\
-            if self.event.style != 'plain' else ("'" if ' ' in
-                                                 self.event.value else None)
-
-    def represent_string(self, data):
-        if isinstance(data, six.binary_type):
-            data = data.decode(self.BINARY_ENCODING)
-        style = "plain"
-        if _has_newline(data):
-            style = "|"
-        elif _LIKE_A_NUMBER.match(data):
-            style = '"'
-        return yaml.representer.ScalarNode('tag:yaml.org,2002:str',
-                                           data, style=style)
-
-    def represent_undefined(self, data):
-        if isinstance(data, collections.OrderedDict):
-            return self.represent_odict(data)
-        else:
-            return super(PrettySafeDumper, self).represent_undefined(data)
-
-    # Override this method to always indent. Otherwise when a list is
-    # emitted, the items nested under it are not and we have inconsistent
-    # formatting.
-    # https://stackoverflow.com/questions/25108581/python-yaml-dump-bad-indentation
-    def increase_indent(self, flow=False, indentless=False):
-        return super(PrettySafeDumper, self).increase_indent(flow, False)
-
-
-# NOTE(harlowja): at some point this may not be needed...
-# See: http://pyyaml.org/ticket/29
-PrettySafeDumper.add_representer(collections.OrderedDict,
-                                 PrettySafeDumper.represent_ordereddict)
-PrettySafeDumper.add_representer(None,
-                                 PrettySafeDumper.represent_undefined)
-
-# NOTE(dhellmann): The representer functions in the base class are
-# specified by class.method-name so we have to re-register the
-# representer for bool if we want to override it.
-PrettySafeDumper.add_representer(bool,
-                                 PrettySafeDumper.represent_bool)
-
-
-# Ensure we use our own routine here, because the style that comes by
-# default is sort of wonky and messes up the values....
-for str_type in [six.binary_type, six.text_type]:
-    PrettySafeDumper.add_representer(str_type,
-                                     PrettySafeDumper.represent_string)
+import ruamel.yaml
+import ruamel.yaml.compat
 
 
 def dumps(obj):
-    """Dump a python object -> blob and apply our pretty styling."""
-    buff = six.StringIO()
-    yaml.dump_all([obj], buff,
-                  explicit_start=True,
-                  indent=2,
-                  default_flow_style=False,
-                  line_break="\n",
-                  width=66,
-                  Dumper=PrettySafeDumper,
-                  allow_unicode=True)
-    return buff.getvalue()
+    """Dumps yaml content into a string."""
+    yaml = ruamel.yaml.YAML()
+    yaml.width = 66
+
+    stream = ruamel.yaml.compat.StringIO()
+    yaml.explicit_start = True
+    yaml.dump(obj, stream)
+    return stream.getvalue()
 
 
 def loads(blob):
     """Load a yaml blob and retain key ordering."""
-    # This does use load, which is unsafe, but should be ok
-    # for what we are loading here in this program; we should
-    # be able to fix that in the future (if it matters).
-    return yaml.load(blob, Loader=yamlordereddictloader.Loader)
+    yaml = ruamel.yaml.YAML()
+    yaml.version = '1.1'
+    return yaml.load(blob)

requirements.txt

@@ -22,6 +22,7 @@ tqdm
 mwclient==0.8.1
 jsonschema>=2.6.0
 twine>=1.13.0
+ruamel.yaml>=0.15
 
 # For release notes generation.
 Jinja2>=2.6  # BSD License (3 clause)