glance_store/glance_store/driver.py
Abhishek Kekane d5dc27e7d3 Add location prefix url to store instance
For updating location metadata with store information to the images
which are existed prior to enabling multiple stores, added new
public attribute 'url_prefix' to each of the store instance.

Implements: blueprint location-uri-prefix

Change-Id: Icd760d30e947867c2b5b87f86bbe4b1a4240d214
2019-06-03 16:16:58 +00:00

288 lines
10 KiB
Python

# Copyright 2011 OpenStack Foundation
# Copyright 2012 RedHat Inc.
# Copyright 2018 Verizon Wireless
# 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.
"""Base class for all storage backends"""
from functools import wraps
import logging
from oslo_config import cfg
from oslo_utils import encodeutils
from oslo_utils import importutils
from oslo_utils import units
import six
from glance_store import capabilities
from glance_store import exceptions
from glance_store.i18n import _
LOG = logging.getLogger(__name__)
_MULTI_BACKEND_OPTS = [
cfg.StrOpt('store_description',
help=_("""
This option will be used to provide a constructive information about
the store backend to end users. Using /v2/stores-info call user can
seek more information on all available backends.
"""))
]
class Store(capabilities.StoreCapability):
OPTIONS = None
MULTI_BACKEND_OPTIONS = _MULTI_BACKEND_OPTS
READ_CHUNKSIZE = 4 * units.Mi # 4M
WRITE_CHUNKSIZE = READ_CHUNKSIZE
def __init__(self, conf, backend=None):
"""
Initialize the Store
"""
super(Store, self).__init__()
self.conf = conf
self.backend_group = backend
self.store_location_class = None
self._url_prefix = None
try:
if self.OPTIONS is not None:
group = 'glance_store'
if self.backend_group:
group = self.backend_group
if self.MULTI_BACKEND_OPTIONS is not None:
self.conf.register_opts(
self.MULTI_BACKEND_OPTIONS, group=group)
self.conf.register_opts(self.OPTIONS, group=group)
except cfg.DuplicateOptError:
pass
@property
def url_prefix(self):
return self._url_prefix
def configure(self, re_raise_bsc=False):
"""
Configure the store to use the stored configuration options
and initialize capabilities based on current configuration.
Any store that needs special configuration should implement
this method.
"""
try:
self.configure_add()
except exceptions.BadStoreConfiguration as e:
self.unset_capabilities(capabilities.BitMasks.WRITE_ACCESS)
msg = (_(u"Failed to configure store correctly: %s "
"Disabling add method.")
% encodeutils.exception_to_unicode(e))
LOG.warning(msg)
if re_raise_bsc:
raise
finally:
self.update_capabilities()
def get_schemes(self):
"""
Returns a tuple of schemes which this store can handle.
"""
raise NotImplementedError
def get_store_location_class(self):
"""
Returns the store location class that is used by this store.
"""
if not self.store_location_class:
class_name = "%s.StoreLocation" % (self.__module__)
LOG.debug("Late loading location class %s", class_name)
self.store_location_class = importutils.import_class(class_name)
return self.store_location_class
def configure_add(self):
"""
This is like `configure` except that it's specifically for
configuring the store to accept objects.
If the store was not able to successfully configure
itself, it should raise `exceptions.BadStoreConfiguration`.
"""
# NOTE(flaper87): This should probably go away
@capabilities.check
def get(self, location, offset=0, chunk_size=None, context=None):
"""
Takes a `glance_store.location.Location` object that indicates
where to find the image file, and returns a tuple of generator
(for reading the image file) and image_size
:param location: `glance_store.location.Location` object, supplied
from glance_store.location.get_location_from_uri()
:raises: `glance.exceptions.NotFound` if image does not exist
"""
raise NotImplementedError
def get_size(self, location, context=None):
"""
Takes a `glance_store.location.Location` object that indicates
where to find the image file, and returns the size
:param location: `glance_store.location.Location` object, supplied
from glance_store.location.get_location_from_uri()
:raises: `glance_store.exceptions.NotFound` if image does not exist
"""
raise NotImplementedError
# NOTE(rosmaita): use the @glance_store.driver.back_compat_add
# annotation on implementions for backward compatibility with
# pre-0.26.0 add(). Need backcompat because pre-0.26.0 returned
# a 4 tuple, this returns a 5-tuple
@capabilities.check
def add(self, image_id, image_file, image_size, hashing_algo,
context=None, verifier=None):
"""
Stores an image file with supplied identifier to the backend
storage system and returns a tuple containing information
about the stored image.
:param image_id: The opaque image identifier
:param image_file: The image data to write, as a file-like object
:param image_size: The size of the image data to write, in bytes
:param hashing_algo: A hashlib algorithm identifier (string)
:param context: A context object
:param verifier: An object used to verify signatures for images
:returns: tuple of: (1) URL in backing store, (2) bytes written,
(3) checksum, (4) multihash value, and (5) a dictionary
with storage system specific information
:raises: `glance_store.exceptions.Duplicate` if the image already
exists
"""
raise NotImplementedError
@capabilities.check
def delete(self, location, context=None):
"""
Takes a `glance_store.location.Location` object that indicates
where to find the image file to delete
:param location: `glance_store.location.Location` object, supplied
from glance_store.location.get_location_from_uri()
:raises: `glance_store.exceptions.NotFound` if image does not exist
"""
raise NotImplementedError
def set_acls(self, location, public=False, read_tenants=None,
write_tenants=None, context=None):
"""
Sets the read and write access control list for an image in the
backend store.
:param location: `glance_store.location.Location` object, supplied
from glance_store.location.get_location_from_uri()
:param public: A boolean indicating whether the image should be public.
:param read_tenants: A list of tenant strings which should be granted
read access for an image.
:param write_tenants: A list of tenant strings which should be granted
write access for an image.
"""
raise NotImplementedError
def back_compat_add(store_add_fun):
"""
Provides backward compatibility for the 0.26.0+ Store.add() function.
In 0.26.0, the 'hashing_algo' parameter is introduced and Store.add()
returns a 5-tuple containing a computed 'multihash' value.
This wrapper behaves as follows:
If no hashing_algo identifier is supplied as an argument, the response
is the pre-0.26.0 4-tuple of::
(backend_url, bytes_written, checksum, metadata_dict)
If a hashing_algo is supplied, the response is a 5-tuple::
(backend_url, bytes_written, checksum, multihash, metadata_dict)
The wrapper detects the presence of a 'hashing_algo' argument both
by examining named arguments and positionally.
"""
@wraps(store_add_fun)
def add_adapter(*args, **kwargs):
"""
Wrapper for the store 'add' function. If no hashing_algo identifier
is supplied, the response is the pre-0.25.0 4-tuple of::
(backend_url, bytes_written, checksum, metadata_dict)
If a hashing_algo is supplied, the response is a 5-tuple::
(backend_url, bytes_written, checksum, multihash, metadata_dict)
"""
# strategy: assume this until we determine otherwise
back_compat_required = True
# specify info about 0.26.0 Store.add() call (can't introspect
# this because the add method is wrapped by the capabilities
# check)
p_algo = 4
max_args = 7
num_args = len(args)
num_kwargs = len(kwargs)
if num_args + num_kwargs == max_args:
# everything is present, including hashing_algo
back_compat_required = False
elif ('hashing_algo' in kwargs or
(num_args >= p_algo + 1 and isinstance(args[p_algo],
six.string_types))):
# there is a hashing_algo argument present
back_compat_required = False
else:
# this is a pre-0.26.0-style call, so let's figure out
# whether to insert the hashing_algo in the args or kwargs
if kwargs and 'image_' in ''.join(kwargs):
# if any of the image_* is named, everything after it
# must be named as well, so slap the algo into kwargs
kwargs['hashing_algo'] = 'md5'
else:
args = args[:p_algo] + ('md5',) + args[p_algo:]
# business time
(backend_url,
bytes_written,
checksum,
multihash,
metadata_dict) = store_add_fun(*args, **kwargs)
if back_compat_required:
return (backend_url, bytes_written, checksum, metadata_dict)
return (backend_url, bytes_written, checksum, multihash,
metadata_dict)
return add_adapter