Add support for API message localization

Using the lazy gettext functionality from oslo gettextutils,
it is possible to use the Accept-Language header to translate
an exception message to the user requested locale and return
that translation from the API.

Implements bp user-locale-api

Change-Id: I48de5e681827305eef60c7a77e8d3091f9d64be0
Co-authored-by: Mathew Odden <mrodden@us.ibm.com>
Co-authored-by: Ben Nemec <openstack@nemebean.com>

ceilometer/api/app.py

@@ -59,7 +59,8 @@ def setup_app(pecan_config=None, extra_hooks=None):
                      storage_engine,
                      storage_engine.get_connection(cfg.CONF),
                  ),
-                 hooks.PipelineHook()]
+                 hooks.PipelineHook(),
+                 hooks.TranslationHook()]
     if extra_hooks:
         app_hooks.extend(extra_hooks)
 

ceilometer/api/controllers/v2.py

@@ -704,9 +704,11 @@ class ResourcesController(rest.RestController):
         # FIXME (flwang): Need to change this to return a 404 error code when
         # we get a release of WSME that supports it.
         if not resources:
+            error = _("Unknown resource")
+            pecan.response.translatable_error = error
             raise wsme.exc.InvalidInput("resource_id",
                                         resource_id,
-                                        _("Unknown resource"))
+                                        error)
         return Resource.from_db_and_links(resources[0],
                                           self._resource_links(resource_id))
 
@@ -836,14 +838,18 @@ class AlarmsController(rest.RestController):
         alarms = list(conn.get_alarms(name=data.name,
                                       project=data.project_id))
         if len(alarms) > 0:
-            raise wsme.exc.ClientSideError(_("Alarm with that name exists"))
+            error = _("Alarm with that name exists")
+            pecan.response.translatable_error = error
+            raise wsme.exc.ClientSideError(error)
 
         try:
             kwargs = data.as_dict(storage.models.Alarm)
             alarm_in = storage.models.Alarm(**kwargs)
         except Exception as ex:
             LOG.exception(ex)
-            raise wsme.exc.ClientSideError(_("Alarm incorrect"))
+            error = _("Alarm incorrect")
+            pecan.response.translatable_error = error
+            raise wsme.exc.ClientSideError(error)
 
         alarm = conn.update_alarm(alarm_in)
         return Alarm.from_db_model(alarm)
@@ -860,7 +866,9 @@ class AlarmsController(rest.RestController):
         alarms = list(conn.get_alarms(alarm_id=alarm_id,
                                       project=auth_project))
         if len(alarms) < 1:
-            raise wsme.exc.ClientSideError(_("Unknown alarm"))
+            error = _("Unknown alarm")
+            pecan.response.translatable_error = error
+            raise wsme.exc.ClientSideError(error)
 
         # merge the new values from kwargs into the current
         # alarm "alarm_in".
@@ -882,7 +890,9 @@ class AlarmsController(rest.RestController):
         alarms = list(conn.get_alarms(alarm_id=alarm_id,
                                       project=auth_project))
         if len(alarms) < 1:
-            raise wsme.exc.ClientSideError(_("Unknown alarm"))
+            error = _("Unknown alarm")
+            pecan.response.translatable_error = error
+            raise wsme.exc.ClientSideError(error)
 
         conn.delete_alarm(alarm_id)
 
@@ -896,7 +906,9 @@ class AlarmsController(rest.RestController):
         # FIXME (flwang): Need to change this to return a 404 error code when
         # we get a release of WSME that supports it.
         if len(alarms) < 1:
-            raise wsme.exc.ClientSideError(_("Unknown alarm"))
+            error = _("Unknown alarm")
+            pecan.response.translatable_error = error
+            raise wsme.exc.ClientSideError(error)
 
         return Alarm.from_db_model(alarms[0])
 

ceilometer/api/hooks.py

@@ -17,6 +17,7 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+import threading
 from oslo.config import cfg
 from pecan import hooks
 
@@ -61,3 +62,18 @@ class PipelineHook(hooks.PecanHook):
 
     def before(self, state):
         state.request.pipeline_manager = self.pipeline_manager
+
+
+class TranslationHook(hooks.PecanHook):
+
+    def __init__(self):
+        # Use thread local storage to make this thread safe in situations
+        # where one pecan instance is being used to serve multiple request
+        # threads.
+        self.local_error = threading.local()
+        self.local_error.translatable_error = None
+
+    def after(self, state):
+        if hasattr(state.response, 'translatable_error'):
+            self.local_error.translatable_error = (
+                state.response.translatable_error)

ceilometer/api/middleware.py

@@ -1,5 +1,6 @@
 # -*- encoding: utf-8 -*-
 #
+# Copyright 2013 IBM Corp.
 # Copyright © 2012 New Dream Network, LLC (DreamHost)
 #
 # Author: Doug Hellmann <doug.hellmann@dreamhost.com>
@@ -29,6 +30,8 @@ try:
 except ImportError:
     from xml.parsers.expat import ExpatError as ParseError
 
+from ceilometer.api import hooks
+from ceilometer.openstack.common import gettextutils
 from ceilometer.openstack.common import log
 
 LOG = log.getLogger(__name__)
@@ -72,13 +75,32 @@ class ParsableErrorMiddleware(object):
         app_iter = self.app(environ, replacement_start_response)
         if (state['status_code'] / 100) not in (2, 3):
             req = webob.Request(environ)
+            # Find the first TranslationHook in the array of hooks and use the
+            # translatable_error object from it
+            error = None
+            for hook in self.app.hooks:
+                if isinstance(hook, hooks.TranslationHook):
+                    error = hook.local_error.translatable_error
+                    break
+            user_locale = req.accept_language.best_match(
+                gettextutils.get_available_languages('ceilometer'),
+                default_match='en_US')
+
             if (req.accept.best_match(['application/json', 'application/xml'])
                == 'application/xml'):
                 try:
                     # simple check xml is valid
+                    fault = et.ElementTree.fromstring('\n'.join(app_iter))
+                    # Add the translated error to the xml data
+                    if error is not None:
+                        for fault_string in fault.findall('faultstring'):
+                            fault_string.text = (
+                                gettextutils.get_localized_message(
+                                    error, user_locale))
                     body = [et.ElementTree.tostring(
-                            et.ElementTree.fromstring('<error_message>'
+                            et.ElementTree.fromstring(
-                                                      + '\n'.join(app_iter)
+                                '<error_message>'
+                                + et.ElementTree.tostring(fault)
                                 + '</error_message>'))]
                 except ParseError as err:
                     LOG.error('Error parsing HTTP response: %s' % err)
@@ -86,6 +108,14 @@ class ParsableErrorMiddleware(object):
                             + '</error_message>']
                 state['headers'].append(('Content-Type', 'application/xml'))
             else:
+                try:
+                    fault = json.loads('\n'.join(app_iter))
+                    if error is not None and 'faultstring' in fault:
+                        fault['faultstring'] = (
+                            gettextutils.get_localized_message(
+                                error, user_locale))
+                    body = [json.dumps({'error_message': json.dumps(fault)})]
+                except ValueError as err:
                     body = [json.dumps({'error_message': '\n'.join(app_iter)})]
                 state['headers'].append(('Content-Type', 'application/json'))
             state['headers'].append(('Content-Length', len(body[0])))

ceilometer/service.py

@@ -75,7 +75,7 @@ cfg.CONF.register_cli_opts(CLI_OPTIONS, group="service_credentials")
 
 def prepare_service(argv=None):
     eventlet.monkey_patch()
-    gettextutils.install('ceilometer')
+    gettextutils.install('ceilometer', True)
     rpc.set_defaults(control_exchange='ceilometer')
     cfg.set_defaults(log.log_opts,
                      default_log_levels=['amqplib=WARN',

tests/api/v2/test_app.py

@@ -1,5 +1,6 @@
 # -*- encoding: utf-8 -*-
 #
+# Copyright 2013 IBM Corp.
 # Copyright © 2013 Julien Danjou
 #
 # Author: Julien Danjou <julien@danjou.info>
@@ -17,6 +18,7 @@
 # under the License.
 """Test basic ceilometer-api app
 """
+import json
 import os
 
 from oslo.config import cfg
@@ -24,6 +26,7 @@ from oslo.config import cfg
 from ceilometer.api import app
 from ceilometer.api import acl
 from ceilometer import service
+from ceilometer.openstack.common import gettextutils
 from ceilometer.tests import base
 from ceilometer.tests import db as tests_db
 from .base import FunctionalTest
@@ -65,6 +68,11 @@ class TestApiMiddleware(FunctionalTest):
     # This doesn't really matter
     database_connection = tests_db.MongoDBFakeConnectionUrl()
 
+    translated_error = 'Translated error'
+
+    def _fake_get_localized_message(self, message, user_locale):
+        return self.translated_error
+
     def test_json_parsable_error_middleware_404(self):
         response = self.get_json('/invalid_path',
                                  expect_errors=True,
@@ -106,6 +114,21 @@ class TestApiMiddleware(FunctionalTest):
         self.assertEqual(response.content_type, "application/json")
         self.assertTrue(response.json['error_message'])
 
+    def test_json_parsable_error_middleware_translation_400(self):
+        # Ensure translated messages get placed properly into json faults
+        self.stubs.Set(gettextutils, 'get_localized_message',
+                       self._fake_get_localized_message)
+        response = self.get_json('/alarms/-',
+                                 expect_errors=True,
+                                 headers={"Accept":
+                                          "application/json"}
+                                 )
+        self.assertEqual(response.status_int, 400)
+        self.assertEqual(response.content_type, "application/json")
+        self.assertTrue(response.json['error_message'])
+        fault = json.loads(response.json['error_message'])
+        self.assertEqual(fault['faultstring'], self.translated_error)
+
     def test_xml_parsable_error_middleware_404(self):
         response = self.get_json('/invalid_path',
                                  expect_errors=True,
@@ -124,3 +147,20 @@ class TestApiMiddleware(FunctionalTest):
         self.assertEqual(response.status_int, 404)
         self.assertEqual(response.content_type, "application/xml")
         self.assertEqual(response.xml.tag, 'error_message')
+
+    def test_xml_parsable_error_middleware_translation_400(self):
+        # Ensure translated messages get placed properly into xml faults
+        self.stubs.Set(gettextutils, 'get_localized_message',
+                       self._fake_get_localized_message)
+
+        response = self.get_json('/alarms/-',
+                                 expect_errors=True,
+                                 headers={"Accept":
+                                          "application/xml,*/*"}
+                                 )
+        self.assertEqual(response.status_int, 400)
+        self.assertEqual(response.content_type, "application/xml")
+        self.assertEqual(response.xml.tag, 'error_message')
+        fault = response.xml.findall('./error/faultstring')
+        for fault_string in fault:
+            self.assertEqual(fault_string.text, self.translated_error)