Source code for swh.objstorage.backends.libcloud

# Copyright (C) 2016-2017  The Software Heritage developers
# See the AUTHORS file at the top-level directory of this distribution
# License: GNU General Public License version 3, or any later version
# See top-level LICENSE file for more information

import abc
from collections import OrderedDict
from collections.abc import Iterator
from typing import Optional
from urllib.parse import urlencode

from libcloud.storage import providers
import libcloud.storage.drivers.s3
from libcloud.storage.types import ObjectDoesNotExistError, Provider

from swh.model import hashutil
from swh.objstorage.exc import Error, ObjNotFoundError
from swh.objstorage.objstorage import (
    ObjStorage,
    compressors,
    compute_hash,
    decompressors,
)


[docs]def patch_libcloud_s3_urlencode(): """Patches libcloud's S3 backend to properly sign queries. Recent versions of libcloud are not affected (they use signature V4), but 1.5.0 (the one in Debian 9) is.""" def s3_urlencode(params): """Like urllib.parse.urlencode, but sorts the parameters first. This is required to properly compute the request signature, see https://docs.aws.amazon.com/AmazonS3/latest/dev/RESTAuthentication.html#ConstructingTheCanonicalizedResourceElement """ # noqa return urlencode(OrderedDict(sorted(params.items()))) libcloud.storage.drivers.s3.urlencode = s3_urlencode
patch_libcloud_s3_urlencode()
[docs]class CloudObjStorage(ObjStorage, metaclass=abc.ABCMeta): """Abstract ObjStorage that connect to a cloud using Libcloud Implementations of this class must redefine the _get_provider method to make it return a driver provider (i.e. object that supports `get_driver` method) which return a LibCloud driver (see https://libcloud.readthedocs.io/en/latest/storage/api.html). Args: container_name: Name of the base container path_prefix: prefix to prepend to object paths in the container, separated with a slash compression: compression algorithm to use for objects kwargs: extra arguments are passed through to the LibCloud driver """ def __init__( self, container_name: str, compression: Optional[str] = None, path_prefix: Optional[str] = None, **kwargs, ): super().__init__(**kwargs) self.driver = self._get_driver(**kwargs) self.container_name = container_name self.container = self.driver.get_container(container_name=container_name) self.compression = compression self.path_prefix = None if path_prefix: self.path_prefix = path_prefix.rstrip("/") + "/" def _get_driver(self, **kwargs): """Initialize a driver to communicate with the cloud Kwargs: arguments passed to the StorageDriver class, typically key: key to connect to the API. secret: secret key for authentication. secure: (bool) support HTTPS host: (str) port: (int) api_version: (str) region: (str) Returns: a Libcloud driver to a cloud storage. """ # Get the driver class from its description. cls = providers.get_driver(self._get_provider()) # Initialize the driver. return cls(**kwargs) @abc.abstractmethod def _get_provider(self): """Get a libcloud driver provider This method must be overridden by subclasses to specify which of the native libcloud driver the current storage should connect to. Alternatively, provider for a custom driver may be returned, in which case the provider will have to support `get_driver` method. """ raise NotImplementedError( "%s must implement `get_provider` method" % type(self) )
[docs] def check_config(self, *, check_write): """Check the configuration for this object storage""" # FIXME: hopefully this blew up during instantiation return True
def __contains__(self, obj_id): try: self._get_object(obj_id) except ObjNotFoundError: return False else: return True def __iter__(self): """ Iterate over the objects present in the storage Warning: Iteration over the contents of a cloud-based object storage may have bad efficiency: due to the very high amount of objects in it and the fact that it is remote, get all the contents of the current object storage may result in a lot of network requests. You almost certainly don't want to use this method in production. """ for obj in self.driver.iterate_container_objects(self.container): name = obj.name if self.path_prefix and not name.startswith(self.path_prefix): continue if self.path_prefix: name = name[len(self.path_prefix) :] yield hashutil.hash_to_bytes(name) def __len__(self): """Compute the number of objects in the current object storage. Warning: this currently uses `__iter__`, its warning about bad performance applies. Returns: number of objects contained in the storage. """ return sum(1 for i in self)
[docs] def add(self, content, obj_id=None, check_presence=True): if obj_id is None: # Checksum is missing, compute it on the fly. obj_id = compute_hash(content) if check_presence and obj_id in self: return obj_id self._put_object(content, obj_id) return obj_id
[docs] def restore(self, content, obj_id=None): return self.add(content, obj_id, check_presence=False)
[docs] def get(self, obj_id): obj = b"".join(self._get_object(obj_id).as_stream()) d = decompressors[self.compression]() ret = d.decompress(obj) if d.unused_data: hex_obj_id = hashutil.hash_to_hex(obj_id) raise Error("Corrupt object %s: trailing data found" % hex_obj_id) return ret
[docs] def check(self, obj_id): # Check that the file exists, as _get_object raises ObjNotFoundError self._get_object(obj_id) # Check the content integrity obj_content = self.get(obj_id) content_obj_id = compute_hash(obj_content) if content_obj_id != obj_id: raise Error(obj_id)
[docs] def delete(self, obj_id): super().delete(obj_id) # Check delete permission obj = self._get_object(obj_id) return self.driver.delete_object(obj)
def _object_path(self, obj_id): """Get the full path to an object""" hex_obj_id = hashutil.hash_to_hex(obj_id) if self.path_prefix: return self.path_prefix + hex_obj_id else: return hex_obj_id def _get_object(self, obj_id): """Get a Libcloud wrapper for an object pointer. This wrapper does not retrieve the content of the object directly. """ object_path = self._object_path(obj_id) try: return self.driver.get_object(self.container_name, object_path) except ObjectDoesNotExistError: raise ObjNotFoundError(obj_id) def _compressor(self, data): comp = compressors[self.compression]() for chunk in data: cchunk = comp.compress(chunk) if cchunk: yield cchunk trail = comp.flush() if trail: yield trail def _put_object(self, content, obj_id): """Create an object in the cloud storage. Created object will contain the content and be referenced by the given id. """ object_path = self._object_path(obj_id) if not isinstance(content, Iterator): content = (content,) self.driver.upload_object_via_stream( self._compressor(content), self.container, object_path )
[docs]class AwsCloudObjStorage(CloudObjStorage): """ Amazon's S3 Cloud-based object storage """ def _get_provider(self): return Provider.S3
[docs]class OpenStackCloudObjStorage(CloudObjStorage): """ OpenStack Swift Cloud based object storage """ def _get_provider(self): return Provider.OPENSTACK_SWIFT