openstack
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glance_store
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glance_store/glance_store/location.py

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# 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/<IMAGE_ID>.
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 logging
import urllib.parse
from oslo_config import cfg
from glance_store import exceptions
from glance_store.i18n import _
CONF = cfg.CONF
LOG = logging.getLogger(__name__)
SCHEME_TO_CLS_MAP = {}
SCHEME_TO_CLS_BACKEND_MAP = {}
def get_location_from_uri(uri, conf=CONF):
"""
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.
:param conf: The global configuration.
Example URIs:
https://user:pass@example.com:80/images/some-id
http://example.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
file:///var/lib/glance/images/1
cinder://volume-id
s3://accesskey:secretkey@s3.amazonaws.com/bucket/key-id
s3+https://accesskey:secretkey@s3.amazonaws.com/bucket/key-id
"""
pieces = urllib.parse.urlparse(uri)
if pieces.scheme not in SCHEME_TO_CLS_MAP.keys():
raise exceptions.UnknownScheme(scheme=pieces.scheme)
scheme_info = SCHEME_TO_CLS_MAP[pieces.scheme]
return Location(pieces.scheme, scheme_info['location_class'],
conf, uri=uri)
def get_location_from_uri_and_backend(uri, backend, conf=CONF):
"""Extract backend location from a 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.
:param backend: A backend name for the store.
:param conf: The global configuration.
Example URIs:
https://user:pass@example.com:80/images/some-id
http://example.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
file:///var/lib/glance/images/1
cinder://volume-id
s3://accesskey:secretkey@s3.amazonaws.com/bucket/key-id
s3+https://accesskey:secretkey@s3.amazonaws.com/bucket/key-id
"""
pieces = urllib.parse.urlparse(uri)
if pieces.scheme not in SCHEME_TO_CLS_BACKEND_MAP.keys():
raise exceptions.UnknownScheme(scheme=pieces.scheme)
try:
scheme_info = SCHEME_TO_CLS_BACKEND_MAP[pieces.scheme][backend]
except KeyError:
raise exceptions.UnknownScheme(scheme=backend)
return Location(pieces.scheme, scheme_info['location_class'],
conf, uri=uri, backend=backend)
def register_scheme_backend_map(scheme_map):
"""Registers a mapping between a scheme and a backend.
Given a mapping of 'scheme' to store_name, adds the mapping to the
known list of schemes.
This function overrides existing stores.
"""
for (k, v) in scheme_map.items():
if k not in SCHEME_TO_CLS_BACKEND_MAP:
SCHEME_TO_CLS_BACKEND_MAP[k] = {}
LOG.debug("Registering scheme %s with %s", k, v)
for key, value in v.items():
SCHEME_TO_CLS_BACKEND_MAP[k][key] = value
def register_scheme_map(scheme_map):
"""
Given a mapping of 'scheme' to store_name, adds the mapping to the
known list of schemes.
This function overrides existing stores.
"""
for (k, v) in scheme_map.items():
LOG.debug("Registering scheme %s with %s", k, v)
SCHEME_TO_CLS_MAP[k] = v
class Location(object):
"""
Class describing the location of an image that Glance knows about
"""
def __init__(self, store_name, store_location_class, conf,
uri=None, image_id=None, store_specs=None, backend=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
:param backend: Name of store backend
"""
self.store_name = store_name
self.image_id = image_id
self.store_specs = store_specs or {}
self.conf = conf
self.backend_group = backend
self.store_location = store_location_class(
self.store_specs, conf, backend_group=backend)
if uri:
self.store_location.parse_uri(uri)
def get_store_uri(self):
"""
Returns the Glance image URI, which is the host:port of the API server
along with /images/<IMAGE_ID>
"""
return self.store_location.get_uri()
def get_uri(self):
return None
class StoreLocation(object):
"""
Base class that must be implemented by each store
"""
def __init__(self, store_specs, conf, backend_group=None):
self.conf = conf
self.specs = store_specs
self.backend_group = backend_group
if self.specs:
self.process_specs()
def process_specs(self):
"""
Subclasses should implement any processing of the self.specs collection
such as storing credentials and possibly establishing connections.
"""
pass
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()")
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()")
@staticmethod
def validate_schemas(uri, valid_schemas):
"""check if uri scheme is one of valid_schemas
generate exception otherwise
"""
for valid_schema in valid_schemas:
if uri.startswith(valid_schema):
return
reason = _("Location URI must start with one of the following "
"schemas: %s") % ', '.join(valid_schemas)
LOG.warning(reason)
raise exceptions.BadStoreUri(message=reason)
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