168 lines
5.9 KiB
Python
168 lines
5.9 KiB
Python
# Copyright 2011 OpenStack Foundation
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# Copyright 2012 RedHat Inc.
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""Base class for all storage backends"""
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from glance.common import exception
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from glance.openstack.common import importutils
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import glance.openstack.common.log as logging
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from glance.openstack.common import strutils
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from glance.openstack.common import units
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LOG = logging.getLogger(__name__)
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def _exception_to_unicode(exc):
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try:
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return unicode(exc)
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except UnicodeError:
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try:
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return strutils.safe_decode(str(exc), errors='ignore')
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except UnicodeError:
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msg = (_("Caught '%(exception)s' exception.") %
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{"exception": exc.__class__.__name__})
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return strutils.safe_decode(msg, errors='ignore')
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class Store(object):
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CHUNKSIZE = 16 * units.Mi # 16M
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def __init__(self, context=None, location=None):
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"""
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Initialize the Store
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"""
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self.store_location_class = None
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self.context = context
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self.configure()
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try:
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self.configure_add()
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except exception.BadStoreConfiguration as e:
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self.add = self.add_disabled
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msg = (_(u"Failed to configure store correctly: %s "
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"Disabling add method.") % _exception_to_unicode(e))
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LOG.warn(msg)
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def configure(self):
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"""
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Configure the Store to use the stored configuration options
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Any store that needs special configuration should implement
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this method.
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"""
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pass
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def get_schemes(self):
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"""
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Returns a tuple of schemes which this store can handle.
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"""
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raise NotImplementedError
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def get_store_location_class(self):
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"""
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Returns the store location class that is used by this store.
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"""
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if not self.store_location_class:
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class_name = "%s.StoreLocation" % (self.__module__)
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LOG.debug("Late loading location class %s", class_name)
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self.store_location_class = importutils.import_class(class_name)
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return self.store_location_class
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def configure_add(self):
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"""
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This is like `configure` except that it's specifically for
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configuring the store to accept objects.
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If the store was not able to successfully configure
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itself, it should raise `exception.BadStoreConfiguration`.
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"""
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pass
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def get(self, location):
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"""
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Takes a `glance.store.location.Location` object that indicates
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where to find the image file, and returns a tuple of generator
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(for reading the image file) and image_size
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:param location `glance.store.location.Location` object, supplied
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from glance.store.location.get_location_from_uri()
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:raises `glance.exception.NotFound` if image does not exist
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"""
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raise NotImplementedError
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def get_size(self, location):
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"""
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Takes a `glance.store.location.Location` object that indicates
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where to find the image file, and returns the size
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:param location `glance.store.location.Location` object, supplied
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from glance.store.location.get_location_from_uri()
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:raises `glance.exception.NotFound` if image does not exist
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"""
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raise NotImplementedError
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def add_disabled(self, *args, **kwargs):
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"""
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Add method that raises an exception because the Store was
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not able to be configured properly and therefore the add()
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method would error out.
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"""
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raise exception.StoreAddDisabled
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def add(self, image_id, image_file, image_size):
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"""
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Stores an image file with supplied identifier to the backend
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storage system and returns a tuple containing information
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about the stored image.
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:param image_id: The opaque image identifier
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:param image_file: The image data to write, as a file-like object
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:param image_size: The size of the image data to write, in bytes
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:retval tuple of URL in backing store, bytes written, checksum
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and a dictionary with storage system specific information
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:raises `glance.common.exception.Duplicate` if the image already
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existed
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"""
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raise NotImplementedError
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def delete(self, location):
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"""
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Takes a `glance.store.location.Location` object that indicates
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where to find the image file to delete
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:location `glance.store.location.Location` object, supplied
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from glance.store.location.get_location_from_uri()
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:raises `glance.exception.NotFound` if image does not exist
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"""
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raise NotImplementedError
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def set_acls(self, location, public=False, read_tenants=[],
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write_tenants=[]):
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"""
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Sets the read and write access control list for an image in the
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backend store.
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:location `glance.store.location.Location` object, supplied
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from glance.store.location.get_location_from_uri()
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:public A boolean indicating whether the image should be public.
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:read_tenants A list of tenant strings which should be granted
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read access for an image.
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:write_tenants A list of tenant strings which should be granted
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write access for an image.
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"""
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raise NotImplementedError
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