CORS support for StoryBoard API

Added new middleware that intercepts and decorates all requests in
accordance to the Cross Origin Resource Sharing W3C specification
found at http://www.w3.org/TR/cors/. Permitted origins and cache max
age are configurable, however headers and methods are hard-coded since
those are application-specific. The notification hook was also
updated to only trigger on POST, PUT, and DELETE.

Motivation for this change is to allow js-draft builds of the
storyboard webclient to break the browser sandbox, and become fully
operational by accessing the production storyboard api. Reviewers
interested in seeing a functioning webclient for UI review will no
longer have to download and run their own client.

Patch to make the webclient build support a configurable API backend
is forthcoming.

Change-Id: I7a825820e4edf48cd9552b2c1c656bc7e664a25a
This commit is contained in:
Michael Krotscheck 2014-09-25 13:02:54 -07:00
parent cfaebb4999
commit 2da943a2f4
4 changed files with 144 additions and 1 deletions

View File

@ -50,6 +50,15 @@ lock_path = $state_path/lock
# and subscriptions.
# enable_notifications = True
[cors]
# W3C CORS configuration. For more information, see http://www.w3.org/TR/cors/
# List of permitted CORS domains.
# allowed_origins = https://storyboard.openstack.org, http://localhost:9000
# CORS browser options cache max age (in seconds)
# max_age=3600
[notifications]
# Host of the rabbitmq server.

View File

@ -22,6 +22,7 @@ from wsgiref import simple_server
from storyboard.api.auth.token_storage import impls as storage_impls
from storyboard.api.auth.token_storage import storage
from storyboard.api import config as api_config
from storyboard.api.middleware.cors_middleware import CORSMiddleware
from storyboard.api.middleware import token_middleware
from storyboard.api.middleware import user_id_hook
from storyboard.api.v1.search import impls as search_engine_impls
@ -45,7 +46,16 @@ API_OPTS = [
default=False,
help='Enable Notifications')
]
CORS_OPTS = [
cfg.ListOpt('allowed_origins',
default=None,
help='List of permitted CORS origins.'),
cfg.IntOpt('max_age',
default=3600,
help='Maximum cache age of CORS preflight requests.')
]
CONF.register_opts(API_OPTS)
CONF.register_opts(CORS_OPTS, 'cors')
def get_pecan_config():
@ -95,6 +105,17 @@ def setup_app(pecan_config=None):
app = token_middleware.AuthTokenMiddleware(app)
# Setup CORS
if CONF.cors.allowed_origins:
app = CORSMiddleware(app,
allowed_origins=CONF.cors.allowed_origins,
allowed_methods=['GET', 'POST', 'PUT', 'DELETE',
'OPTIONS'],
allowed_headers=['origin', 'authorization',
'accept', 'x-total', 'x-limit',
'x-marker', 'x-client'],
max_age=CONF.cors.max_age)
return app

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@ -0,0 +1,113 @@
# Copyright (c) 2014 Hewlett-Packard Development Company, L.P.
#
# 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.
# Default allowed headers
ALLOWED_HEADERS = [
'origin',
'authorization',
'accept'
]
# Default allowed methods
ALLOWED_METHODS = [
'GET',
'POST',
'PUT',
'DELETE',
'OPTIONS'
]
class CORSMiddleware(object):
"""CORS Middleware.
By providing a list of allowed origins, methods, headers, and a max-age,
this middleware will detect and apply the appropriate CORS headers so
that your web application may elegantly overcome the browser's
same-origin sandbox.
For more information, see http://www.w3.org/TR/cors/
"""
def __init__(self, app, allowed_origins=None, allowed_methods=None,
allowed_headers=None, max_age=3600):
"""Create a new instance of the CORS middleware.
:param app: The application that is being wrapped.
:param allowed_origins: A list of allowed origins, as provided by the
'Origin:' Http header. Must include protocol, host, and port.
:param allowed_methods: A list of allowed HTTP methods.
:param allowed_headers: A list of allowed HTTP headers.
:param max_age: A maximum CORS cache age in seconds.
:return: A new middleware instance.
"""
# Wrapped app (or other middleware)
self.app = app
# Allowed origins
self.allowed_origins = allowed_origins or []
# List of allowed headers.
self.allowed_headers = ','.join(allowed_headers or ALLOWED_HEADERS)
# List of allowed methods.
self.allowed_methods = ','.join(allowed_methods or ALLOWED_METHODS)
# Cache age.
self.max_age = str(max_age)
def __call__(self, env, start_response):
"""Serve an application request.
:param env: Application environment parameters.
:param start_response: Wrapper method that starts the response.
:return:
"""
origin = env['HTTP_ORIGIN'] if 'HTTP_ORIGIN' in env else ''
method = env['REQUEST_METHOD'] if 'REQUEST_METHOD' in env else ''
def replacement_start_response(status, headers, exc_info=None):
"""Overrides the default response to attach CORS headers.
"""
# Decorate the headers
headers.append(('Access-Control-Allow-Origin',
origin))
headers.append(('Access-Control-Allow-Methods',
self.allowed_methods))
headers.append(('Access-Control-Expose-Headers',
self.allowed_headers))
headers.append(('Access-Control-Allow-Headers',
self.allowed_headers))
headers.append(('Access-Control-Max-Age',
self.max_age))
return start_response(status, headers, exc_info)
# Does this request match one of our origin domains?
if origin in self.allowed_origins:
# Is this an OPTIONS request?
if method == 'OPTIONS':
options_headers = [('Content-Length', '0')]
replacement_start_response('204 No Content', options_headers)
return ''
else:
# Handle the request.
return self.app(env, replacement_start_response)
else:
# This is not a request for a permitted CORS domain. Return
# the response without the appropriate headers and let the browser
# figure out the details.
return self.app(env, start_response)

View File

@ -27,7 +27,7 @@ class NotificationHook(hooks.PecanHook):
def after(self, state):
# Ignore get methods, we only care about changes.
if state.request.method == 'GET':
if state.request.method not in ['POST', 'PUT', 'DELETE']:
return
request = state.request