config-generator yaml format doesn't work with i18n fields

This is because there's no yaml representer for i18n Messages object.
This patch aims to add this representer and allow the generation of
configurations using oslo.i18n strings.

One example of this is cinder.

Closes-bug: #1928582
Change-Id: I70ab87c9bed093cad883b6301b8a09753fc470d9

1 files changed, 14 insertions, 0 deletions

diff --git a/oslo_config/generator.py b/oslo_config/generator.py
index 9845c81..5dd1044 100644
--- a/oslo_config/generator.py
+++ b/oslo_config/generator.py
@@ -52,6 +52,7 @@ except ImportError:
 import yaml
 
 from oslo_config import cfg
+from oslo_i18n import _message
 import stevedore.named  # noqa
 
 LOG = logging.getLogger(__name__)
@@ -723,6 +724,18 @@ def _generate_machine_readable_data(groups, conf):
     return output_data
 
 
+def i18n_representer(dumper, data):
+    """oslo_i18n yaml representer
+
+    Returns a translated to the default locale string for yaml.safe_dump
+
+    :param dumper: a SafeDumper instance passed by yaml.safe_dump
+    :param data: a oslo_i18n._message.Message instance
+    """
+    serializedData = str(data.translation())
+    return dumper.represent_str(serializedData)
+
+
 def _output_machine_readable(groups, output_file, conf):
     """Write a machine readable sample config file
 
@@ -736,6 +749,7 @@ def _output_machine_readable(groups, output_file, conf):
     """
     output_data = _generate_machine_readable_data(groups, conf)
     if conf.format_ == 'yaml':
+        yaml.SafeDumper.add_representer(_message.Message, i18n_representer)
         output_file.write(yaml.safe_dump(output_data,
                                          default_flow_style=False))
     else: