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OpenStack Study: location.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 class that describes the location of an image in Glance. In Glance, an image can either be **stored** in Glance, or it can be **registered** in Glance but actually be stored somewhere else. We needed a class that could support the various ways that Glance describes where exactly an image is stored. An image in Glance has two location properties: the image URI and the image storage URI. The image URI is essentially the permalink identifier for the image. It is displayed in the output of various Glance API calls and, while read-only, is entirely user-facing. It shall **not** contain any security credential information at all. The Glance image URI shall be the host:port of that Glance API server along with /images/ The Glance storage URI is an internal URI structure that Glance uses to maintain critical information about how to access the images that it stores in its storage backends. It **may contain** security credentials and is **not** user-facing. """ import six.moves.urllib.parse as urlparse from glance.common import exception import glance.openstack.common.log as logging LOG = logging.getLogger(__name__) SCHEME_TO_CLS_MAP = {}
**** CubicPower OpenStack Study **** def get_location_from_uri(uri): """ Given a URI, return a Location object that has had an appropriate store parse the URI. :param uri: A URI that could come from the end-user in the Location attribute/header Example URIs: https://user:pass@example.com:80/images/some-id http://images.oracle.com/123456 swift://example.com/container/obj-id swift://user:account:pass@authurl.com/container/obj-id swift+http://user:account:pass@authurl.com/container/obj-id s3://accesskey:secretkey@s3.amazonaws.com/bucket/key-id s3+https://accesskey:secretkey@s3.amazonaws.com/bucket/key-id file:///var/lib/glance/images/1 cinder://volume-id vsphere://server_host/folder/file_path?dcPath=dc_path&dsName=ds_name """ pieces = urlparse.urlparse(uri) if pieces.scheme not in SCHEME_TO_CLS_MAP.keys(): raise exception.UnknownScheme(scheme=pieces.scheme) scheme_info = SCHEME_TO_CLS_MAP[pieces.scheme] return Location(pieces.scheme, uri=uri, store_location_class=scheme_info['location_class'])
**** CubicPower OpenStack Study **** def register_scheme_map(scheme_map): """ Given a mapping of 'scheme' to store_name, adds the mapping to the known list of schemes if it does not already exist. """ for (k, v) in scheme_map.items(): if k not in SCHEME_TO_CLS_MAP: LOG.debug(_("Registering scheme %(k)s with %(v)s") % {'k': k, 'v': v}) SCHEME_TO_CLS_MAP[k] = v
**** CubicPower OpenStack Study **** class Location(object): """ Class describing the location of an image that Glance knows about """
**** CubicPower OpenStack Study **** def __init__(self, store_name, store_location_class, uri=None, image_id=None, store_specs=None): """ Create a new Location object. :param store_name: The string identifier/scheme of the storage backend :param store_location_class: The store location class to use for this location instance. :param image_id: The identifier of the image in whatever storage backend is used. :param uri: Optional URI to construct location from :param store_specs: Dictionary of information about the location of the image that is dependent on the backend store """ self.store_name = store_name self.image_id = image_id self.store_specs = store_specs or {} self.store_location = store_location_class(self.store_specs) if uri: self.store_location.parse_uri(uri)
**** CubicPower OpenStack Study **** def get_store_uri(self): """ Returns the Glance image URI, which is the host:port of the API server along with /images/ """ return self.store_location.get_uri()
**** CubicPower OpenStack Study **** def get_uri(self): return None
**** CubicPower OpenStack Study **** class StoreLocation(object): """ Base class that must be implemented by each store """
**** CubicPower OpenStack Study **** def __init__(self, store_specs): self.specs = store_specs if self.specs: self.process_specs()
**** CubicPower OpenStack Study **** def process_specs(self): """ Subclasses should implement any processing of the self.specs collection such as storing credentials and possibly establishing connections. """ pass
**** CubicPower OpenStack Study **** def get_uri(self): """ Subclasses should implement a method that returns an internal URI that, when supplied to the StoreLocation instance, can be interpreted by the StoreLocation's parse_uri() method. The URI returned from this method shall never be public and only used internally within Glance, so it is fine to encode credentials in this URI. """ raise NotImplementedError("StoreLocation subclass must implement " "get_uri()")
**** CubicPower OpenStack Study **** def parse_uri(self, uri): """ Subclasses should implement a method that accepts a string URI and sets appropriate internal fields such that a call to get_uri() will return a proper internal URI """ raise NotImplementedError("StoreLocation subclass must implement " "parse_uri()")
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