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OpenStack Study: version_negotiation.py**** CubicPower OpenStack Study ****
# Copyright 2011 OpenStack Foundation # All Rights Reserved. # # 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. """ A filter middleware that inspects the requested URI for a version string and/or Accept headers and attempts to negotiate an API controller to return """ from oslo.config import cfg from glance.api import versions from glance.common import wsgi import glance.openstack.common.log as logging CONF = cfg.CONF LOG = logging.getLogger(__name__)
**** CubicPower OpenStack Study **** class VersionNegotiationFilter(wsgi.Middleware):
**** CubicPower OpenStack Study **** def __init__(self, app): self.versions_app = versions.Controller() super(VersionNegotiationFilter, self).__init__(app)
**** CubicPower OpenStack Study **** def process_request(self, req): """Try to find a version first in the accept header, then the URL""" msg = _("Determining version of request: %(method)s %(path)s" " Accept: %(accept)s") args = {'method': req.method, 'path': req.path, 'accept': req.accept} LOG.debug(msg % args) # If the request is for /versions, just return the versions container #TODO(bcwaldon): deprecate this behavior if req.path_info_peek() == "versions": return self.versions_app accept = str(req.accept) if accept.startswith('application/vnd.openstack.images-'): LOG.debug(_("Using media-type versioning")) token_loc = len('application/vnd.openstack.images-') req_version = accept[token_loc:] else: LOG.debug(_("Using url versioning")) # Remove version in url so it doesn't conflict later req_version = self._pop_path_info(req) try: version = self._match_version_string(req_version) except ValueError: LOG.debug(_("Unknown version. Returning version choices.")) return self.versions_app req.environ['api.version'] = version req.path_info = ''.join(('/v', str(version), req.path_info)) LOG.debug(_("Matched version: v%d"), version) LOG.debug('new path %s' % req.path_info) return None
**** CubicPower OpenStack Study **** def _match_version_string(self, subject): """ Given a string, tries to match a major and/or minor version number. :param subject: The string to check :returns version found in the subject :raises ValueError if no acceptable version could be found """ if subject in ('v1', 'v1.0', 'v1.1') and CONF.enable_v1_api: major_version = 1 elif subject in ('v2', 'v2.0', 'v2.1', 'v2.2') and CONF.enable_v2_api: major_version = 2 else: raise ValueError() return major_version
**** CubicPower OpenStack Study **** def _pop_path_info(self, req): """ 'Pops' off the next segment of PATH_INFO, returns the popped segment. Do NOT push it onto SCRIPT_NAME. """ path = req.path_info if not path: return None while path.startswith('/'): path = path[1:] idx = path.find('/') if idx == -1: idx = len(path) r = path[:idx] req.path_info = path[idx:] return r
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