aodh/ceilometer/api/middleware.py
Brad Pokorny 31323859c7 Use system locale when Accept-Language header is not provided
Remove en_US as the default language when no header is provided, and use
None instead. Upon translation None will be defaulted to system as it
was before the translation changes.

Fixes bug 1214476

Change-Id: Ia18ae76f9dc3c93c7d14203af6f65b916500927e
2013-08-26 20:57:44 +00:00

136 lines
5.6 KiB
Python

# -*- encoding: utf-8 -*-
#
# Copyright 2013 IBM Corp.
# Copyright © 2012 New Dream Network, LLC (DreamHost)
#
# Author: Doug Hellmann <doug.hellmann@dreamhost.com>
#
# 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.
"""Middleware to replace the plain text message body of an error
response with one formatted so the client can parse it.
Based on pecan.middleware.errordocument
"""
import json
import webob
from xml import etree as et
try:
from xml.etree.ElementTree import ParseError
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__)
class ParsableErrorMiddleware(object):
"""Replace error body with something the client can parse.
"""
@staticmethod
def best_match_language(accept_language):
"""Determines best available locale from the Accept-Language
header.
:returns: the best language match or None if the 'Accept-Language'
header was not available in the request.
"""
if not accept_language:
return None
all_languages = gettextutils.get_available_languages('ceilometer')
return accept_language.best_match(all_languages)
def __init__(self, app):
self.app = app
def __call__(self, environ, start_response):
# Request for this state, modified by replace_start_response()
# and used when an error is being reported.
state = {}
def replacement_start_response(status, headers, exc_info=None):
"""Overrides the default response to make errors parsable.
"""
try:
status_code = int(status.split(' ')[0])
state['status_code'] = status_code
except (ValueError, TypeError): # pragma: nocover
raise Exception((
'ErrorDocumentMiddleware received an invalid '
'status %s' % status
))
else:
if (state['status_code'] / 100) not in (2, 3):
# Remove some headers so we can replace them later
# when we have the full error message and can
# compute the length.
headers = [(h, v)
for (h, v) in headers
if h not in ('Content-Length', 'Content-Type')
]
# Save the headers in case we need to modify them.
state['headers'] = headers
return start_response(status, headers, exc_info)
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 = self.best_match_language(req.accept_language)
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.tostring(fault)
+ '</error_message>'))]
except ParseError as err:
LOG.error('Error parsing HTTP response: %s' % err)
body = ['<error_message>%s' % state['status_code']
+ '</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])))
else:
body = app_iter
return body