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# Copyright (c) 2010-2015 OpenStack Foundation
#
# 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.
from swift.common.constraints import check_account_format, valid_api_version
from swift.common.swob import HTTPMethodNotAllowed, Request
from swift.common.utils import get_logger, config_true_value
from swift.common.registry import register_swift_info
from swift.proxy.controllers.base import get_info
"""
=========
Read Only
=========
The ability to make an entire cluster or individual accounts read only is
implemented as pluggable middleware. When a cluster or an account is in read
only mode, requests that would result in writes to the cluser are not allowed.
A 405 is returned on such requests. "COPY", "DELETE", "POST", and
"PUT" are the HTTP methods that are considered writes.
-------------
Configuration
-------------
All configuration is optional.
============= ======= ====================================================
Option Default Description
------------- ------- ----------------------------------------------------
read_only false Set to 'true' to put the entire cluster in read only
mode.
allow_deletes false Set to 'true' to allow deletes.
============= ======= ====================================================
---------------------------
Marking Individual Accounts
---------------------------
If a system administrator wants to mark individual accounts as read only,
he/she can set X-Account-Sysmeta-Read-Only on an account to 'true'.
If a system administrator wants to allow writes to individual accounts,
when a cluster is in read only mode, he/she can set
X-Account-Sysmeta-Read-Only on an account to 'false'.
This header will be hidden from the user, because of the gatekeeper middleware,
and can only be set using a direct client to the account nodes.
"""
class ReadOnlyMiddleware(object):
"""
Middleware that make an entire cluster or individual accounts read only.
"""
def __init__(self, app, conf, logger=None):
self.app = app
self.logger = logger or get_logger(conf, log_route='read_only')
self.read_only = config_true_value(conf.get('read_only'))
self.write_methods = {'COPY', 'POST', 'PUT'}
if not config_true_value(conf.get('allow_deletes')):
self.write_methods.add('DELETE')
def __call__(self, env, start_response):
req = Request(env)
if req.method not in self.write_methods:
return self.app(env, start_response)
try:
version, account, container, obj = req.split_path(2, 4, True)
if not valid_api_version(version):
raise ValueError
except ValueError:
return self.app(env, start_response)
if req.method == 'COPY' and 'Destination-Account' in req.headers:
dest_account = req.headers.get('Destination-Account')
account = check_account_format(req, dest_account)
if self.account_read_only(req, account):
msg = 'Writes are disabled for this account.'
return HTTPMethodNotAllowed(body=msg)(env, start_response)
return self.app(env, start_response)
def account_read_only(self, req, account):
"""
Check whether an account should be read-only.
This considers both the cluster-wide config value as well as the
per-account override in X-Account-Sysmeta-Read-Only.
"""
info = get_info(self.app, req.environ, account, swift_source='RO')
read_only = info.get('sysmeta', {}).get('read-only', '')
if not read_only:
return self.read_only
return config_true_value(read_only)
def filter_factory(global_conf, **local_conf):
"""
paste.deploy app factory for creating WSGI proxy apps.
"""
conf = global_conf.copy()
conf.update(local_conf)
if config_true_value(conf.get('read_only')):
register_swift_info('read_only')
def read_only_filter(app):
return ReadOnlyMiddleware(app, conf)
return read_only_filter
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