deb-cinder/cinder/api/views/versions.py
scottda 6b11d276d1 cinder-api-microversions code
Many changes to the Cinder REST API require changes to the consumers of the API.
For example, If we need to add a required parameter to a method that is called
 by Nova, we'd need both the Nova calling code and the cinderclient that
Nova uses to change. But newer Cinder versions with the change must work with
older Nova versions, and there is no mechanism for this at the moment. Adding
microversions will solve this problem.
With microversions, the highest supported version will be negotiated by a field
in the HTTP header that is sent to the Cinder API. In the case where the field
'versions' is not sent (i.e. clients and scripts that pre-date this change),
then the lowest supported version would be used. In order to ensure that the
API consumer is explicitly asking for a microversioned API, a new endpoint v3
is added, which is identical to API version v2. This means that our new
Cinder API v3 would be the default, and consumers of the API that wished to
use a newer version could do so by using that endpoint and a microversion in
the HTTP header.
New tests for microversioned API features on endpoint /v3 should be added to
cinder/tests/unit/api/v3/ directory. Existing functionality will be tested via
the .../v2/ unit tests.

DocImpact
APIImpact
Implements: https://blueprints.launchpad.net/cinder/+spec/cinder-api-microversions
Change-Id: I48cdbbc900c2805e59ee9aebc3b1c64aed3212ae
2016-02-24 06:50:54 -07:00

79 lines
2.7 KiB
Python

# Copyright 2010-2011 OpenStack Foundation
# Copyright 2015 Clinton Knight
# 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.
import copy
import re
from oslo_config import cfg
from six.moves import urllib
versions_opts = [
cfg.StrOpt('public_endpoint',
help="Public url to use for versions endpoint. The default "
"is None, which will use the request's host_url "
"attribute to populate the URL base. If Cinder is "
"operating behind a proxy, you will want to change "
"this to represent the proxy's URL."),
]
CONF = cfg.CONF
CONF.register_opts(versions_opts)
def get_view_builder(req):
base_url = CONF.public_endpoint or req.application_url
return ViewBuilder(base_url)
class ViewBuilder(object):
def __init__(self, base_url):
"""Initialize ViewBuilder.
:param base_url: url of the root wsgi application
"""
self.base_url = base_url
def build_versions(self, versions):
views = [self._build_version(versions[key])
for key in sorted(list(versions.keys()))]
return dict(versions=views)
def _build_version(self, version):
view = copy.deepcopy(version)
view['links'] = self._build_links(version)
return view
def _build_links(self, version_data):
"""Generate a container of links that refer to the provided version."""
links = copy.deepcopy(version_data.get('links', {}))
version_num = version_data["id"].split('.')[0]
links.append({'rel': 'self',
'href': self._generate_href(version=version_num)})
return links
def _generate_href(self, version='v3', path=None):
"""Create a URL that refers to a specific version_number."""
base_url = self._get_base_url_without_version()
href = urllib.parse.urljoin(base_url, version).rstrip('/') + '/'
if path:
href += path.lstrip('/')
return href
def _get_base_url_without_version(self):
"""Get the base URL with out the /v1 suffix."""
return re.sub('v[1-9]+/?$', '', self.base_url)