Introduce a base yaml parser for all openstack components

A lot of openstack components like:
- solum
- tosca-parser
- heat
- murano
- etc...

reimplement theirs own yaml parser for loading and dumping.

These implementations sometimes forgot to use a safe loader
or safe dumper, our implementation use safe by default.

You can deactive safe by passing the argument is_safe to false when
you call oslo_serialization.yamlutils.load or oslo_serialization.yamlutils.dump.

Change-Id: I63e85a2b4fc999e6acac12ae51c2ab8c64bddbc6
Co-Authored-By: Natal Ngétal <hobbestigrou@erakis.eu>

oslo_serialization/tests/test_yamlutils.py

@@ -0,0 +1,85 @@
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import os
+import tempfile
+import textwrap
+import uuid
+
+from oslotest import base
+
+from oslo_serialization import yamlutils as yaml
+
+
+class BehaviorTestCase(base.BaseTestCase):
+
+    def test_loading(self):
+        payload = textwrap.dedent('''
+            - foo: bar
+            - list:
+            - [one, two]
+            - {check: yaml, in: test}
+        ''')
+        expected = [
+            {'foo': 'bar'},
+            {'list': None},
+            ['one', 'two'],
+            {'check': 'yaml', 'in': 'test'}
+        ]
+        loaded = yaml.load(payload)
+        self.assertEqual(loaded, expected)
+
+    def test_loading_with_unsafe(self):
+        payload = textwrap.dedent('''
+            !!python/object/apply:os.system ['echo "hello"']
+        ''')
+        loaded = yaml.load(payload, is_safe=False)
+        expected = 0
+        self.assertEqual(loaded, expected)
+
+    def test_dumps(self):
+        payload = [
+            {'foo': 'bar'},
+            {'list': None},
+            ['one', 'two'],
+            {'check': 'yaml', 'in': 'test'}
+        ]
+        dumped = yaml.dumps(payload)
+        expected = textwrap.dedent('''\
+            - {foo: bar}
+            - {list: null}
+            - [one, two]
+            - {check: yaml, in: test}
+        ''')
+        self.assertEqual(dumped, expected)
+
+    def test_dump(self):
+        payload = [
+            {'foo': 'bar'},
+            {'list': None},
+            ['one', 'two'],
+            {'check': 'yaml', 'in': 'test'}
+        ]
+        tmpfile = os.path.join(tempfile.gettempdir(), str(uuid.uuid4()))
+        with open(tmpfile, 'w+') as fp:
+            yaml.dump(payload, fp)
+        with open(tmpfile, 'r') as fp:
+            file_content = fp.read()
+            expected = textwrap.dedent('''\
+                - foo: bar
+                - list: null
+                - - one
+                  - two
+                - check: yaml
+                  in: test
+            ''')
+            self.assertEqual(file_content, expected)

oslo_serialization/yamlutils.py

@@ -0,0 +1,86 @@
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+"""YAML related utilities.
+
+The main goal of this module is to standardize yaml management inside
+openstack. This module reduce technical debt by avoiding re-implementations
+of yaml manager in all the openstack projects.
+Use this module inside openstack projects to handle yaml securely and properly.
+"""
+
+import yaml
+
+
+def load(stream, is_safe=True):
+    """Converts a YAML document to a Python object.
+
+    :param stream: the YAML document to convert into a Python object. Accepts
+                   a byte string, a Unicode string, an open binary file object,
+                   or an open text file object.
+    :param is_safe: Turn off safe loading. True by default and only load
+                    standard YAML. This option can be turned off by
+                    passing ``is_safe=False`` if you need to load not only
+                    standard YAML tags or if you need to construct an
+                    arbitrary python object.
+
+    Stream specifications:
+
+    * An empty stream contains no documents.
+    * Documents are separated with ``---``.
+    * Documents may optionally end with ``...``.
+    * A single document may or may not be marked with ``---``.
+
+    Parses the given stream and returns a Python object constructed
+    from the first document in the stream. If there are no documents
+    in the stream, it returns None.
+    """
+    yaml_loader = yaml.Loader
+    if is_safe:
+        if hasattr(yaml, 'CSafeLoader'):
+            yaml_loader = yaml.CSafeLoader
+        else:
+            yaml_loader = yaml.SafeLoader
+    return yaml.load(stream, yaml_loader)  # nosec B506
+
+
+def dumps(obj, is_safe=True):
+    """Converts a Python object to a YAML document.
+
+    :param obj: python object to convert into YAML representation.
+    :param is_safe: Turn off safe dumping.
+
+    Serializes the given Python object to a string and returns that string.
+    """
+    yaml_dumper = yaml.Dumper
+    if is_safe:
+        if hasattr(yaml, 'CSafeDumper'):
+            yaml_dumper = yaml.CSafeDumper
+        else:
+            yaml_dumper = yaml.SafeDumper
+    return yaml.dump(obj, Dumper=yaml_dumper)
+
+
+def dump(obj, fp, is_safe=True):
+    """Converts a Python object as a YAML document to ``fp``.
+
+    :param obj: python object to convert into YAML representation.
+    :param fp: a ``.write()``-supporting file-like object
+    :param is_safe: Turn off safe dumping.
+    """
+    yaml_dumper = yaml.Dumper
+    if is_safe:
+        if hasattr(yaml, 'CSafeDumper'):
+            yaml_dumper = yaml.CSafeDumper
+        else:
+            yaml_dumper = yaml.SafeDumper
+    return yaml.dump(obj, fp, default_flow_style=False, Dumper=yaml_dumper)

requirements.txt

@@ -12,3 +12,4 @@ six>=1.10.0 # MIT
 msgpack>=0.5.2 # Apache-2.0
 oslo.utils>=3.33.0 # Apache-2.0
 pytz>=2013.6 # MIT
+PyYAML>=3.12 # MIT