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# Copyright (C) 2016-2021 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 asyncio
import contextlib
import datetime
from itertools import product
import string
from typing import Dict, Optional, Union
import warnings
from azure.core.exceptions import ResourceExistsError, ResourceNotFoundError
from azure.storage.blob import (
ContainerClient,
ContainerSasPermissions,
generate_container_sas,
)
from azure.storage.blob.aio import ContainerClient as AsyncContainerClient
from swh.model import hashutil
from swh.objstorage.exc import Error, ObjNotFoundError
from swh.objstorage.objstorage import (
ObjStorage,
compressors,
compute_hash,
decompressors,
)
from swh.objstorage.utils import call_async
def get_container_url(
account_name: str,
account_key: str,
container_name: str,
access_policy: str = "read_only",
expiry: datetime.timedelta = datetime.timedelta(days=365),
**kwargs,
) -> str:
"""Get the full url, for the given container on the given account, with a
Shared Access Signature granting the specified access policy.
Args:
account_name: name of the storage account for which to generate the URL
account_key: shared account key of the storage account used to generate the SAS
container_name: name of the container for which to grant access in the storage
account
access_policy: one of ``read_only``, ``append_only``, ``full``
expiry: the interval in the future with which the signature will expire
Returns:
the full URL of the container, with the shared access signature.
"""
access_policies = {
"read_only": ContainerSasPermissions(
read=True, list=True, delete=False, write=False
),
"append_only": ContainerSasPermissions(
read=True, list=True, delete=False, write=True
),
"full": ContainerSasPermissions(read=True, list=True, delete=True, write=True),
}
current_time = datetime.datetime.utcnow()
signature = generate_container_sas(
account_name,
container_name,
account_key=account_key,
permission=access_policies[access_policy],
start=current_time + datetime.timedelta(minutes=-1),
expiry=current_time + expiry,
)
return f"https://{account_name}.blob.core.windows.net/{container_name}?{signature}"
class AzureCloudObjStorage(ObjStorage):
"""ObjStorage backend for Azure blob storage accounts.
Args:
container_url: the URL of the container in which the objects are stored.
account_name: (deprecated) the name of the storage account under which objects are
stored
api_secret_key: (deprecated) the shared account key
container_name: (deprecated) the name of the container under which objects are
stored
compression: the compression algorithm used to compress objects in storage
Notes:
The container url should contain the credentials via a "Shared Access
Signature". The :func:`get_container_url` helper can be used to generate
such a URL from the account's access keys. The ``account_name``,
``api_secret_key`` and ``container_name`` arguments are deprecated.
"""
def __init__(
self,
container_url: Optional[str] = None,
account_name: Optional[str] = None,
api_secret_key: Optional[str] = None,
container_name: Optional[str] = None,
compression="gzip",
**kwargs,
):
if container_url is None:
if account_name is None or api_secret_key is None or container_name is None:
raise ValueError(
"AzureCloudObjStorage must have a container_url or all three "
"account_name, api_secret_key and container_name"
)
else:
warnings.warn(
"The Azure objstorage account secret key parameters are "
"deprecated, please use container URLs instead.",
DeprecationWarning,
)
container_url = get_container_url(
account_name=account_name,
account_key=api_secret_key,
container_name=container_name,
access_policy="full",
)
super().__init__(**kwargs)
self.container_url = container_url
self.compression = compression
def get_container_client(self, hex_obj_id):
"""Get the container client for the container that contains the object with
internal id hex_obj_id
This is used to allow the PrefixedAzureCloudObjStorage to dispatch the
client according to the prefix of the object id.
"""
return ContainerClient.from_container_url(self.container_url)
@contextlib.asynccontextmanager
async def get_async_container_clients(self):
"""Returns a collection of container clients, to be passed to
``get_async_blob_client``.
Each container may not be used in more than one asyncio loop."""
client = AsyncContainerClient.from_container_url(self.container_url)
async with client:
yield {"": client}
def get_blob_client(self, hex_obj_id):
"""Get the azure blob client for the given hex obj id"""
container_client = self.get_container_client(hex_obj_id)
return container_client.get_blob_client(blob=hex_obj_id)
def get_async_blob_client(self, hex_obj_id, container_clients):
"""Get the azure blob client for the given hex obj id and a collection
yielded by ``get_async_container_clients``."""
return container_clients[""].get_blob_client(blob=hex_obj_id)
def get_all_container_clients(self):
"""Get all active block_blob_services"""
yield self.get_container_client("")
def _internal_id(self, obj_id):
"""Internal id is the hex version in objstorage.
"""
return hashutil.hash_to_hex(obj_id)
def check_config(self, *, check_write):
"""Check the configuration for this object storage"""
for container_client in self.get_all_container_clients():
props = container_client.get_container_properties()
# FIXME: check_write is ignored here
if not props:
return False
return True
def __contains__(self, obj_id):
"""Does the storage contains the obj_id.
"""
hex_obj_id = self._internal_id(obj_id)
client = self.get_blob_client(hex_obj_id)
try:
client.get_blob_properties()
except ResourceNotFoundError:
return False
else:
return True
def __iter__(self):
"""Iterate over the objects present in the storage.
"""
for client in self.get_all_container_clients():
for obj in client.list_blobs():
yield hashutil.hash_to_bytes(obj.name)
def __len__(self):
"""Compute the number of objects in the current object storage.
Returns:
number of objects contained in the storage.
"""
return sum(1 for i in self)
def add(self, content, obj_id=None, check_presence=True):
"""Add an obj in storage if it's not there already.
"""
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
hex_obj_id = self._internal_id(obj_id)
# Send the compressed content
compressor = compressors[self.compression]()
data = compressor.compress(content)
data += compressor.flush()
client = self.get_blob_client(hex_obj_id)
try:
client.upload_blob(data=data, length=len(data))
except ResourceExistsError:
# There's a race condition between check_presence and upload_blob,
# that we can't get rid of as the azure api doesn't allow atomic
# replaces or renaming a blob. As the restore operation explicitly
# removes the blob, it should be safe to just ignore the error.
pass
return obj_id
def restore(self, content, obj_id=None):
"""Restore a content.
"""
if obj_id is None:
# Checksum is missing, compute it on the fly.
obj_id = compute_hash(content)
if obj_id in self:
self.delete(obj_id)
return self.add(content, obj_id, check_presence=False)
def get(self, obj_id):
"""retrieve blob's content if found.
"""
return call_async(self._get_async, obj_id)
async def _get_async(self, obj_id, container_clients=None):
"""Coroutine implementing ``get(obj_id)`` using azure-storage-blob's
asynchronous implementation.
While ``get(obj_id)`` does not need asynchronicity, this is useful to
``get_batch(obj_ids)``, as it can run multiple ``_get_async`` tasks
concurrently."""
if container_clients is None:
# If the container_clients argument is not passed, create a new
# collection of container_clients and restart the function with it.
async with self.get_async_container_clients() as container_clients:
return await self._get_async(obj_id, container_clients)
hex_obj_id = self._internal_id(obj_id)
client = self.get_async_blob_client(hex_obj_id, container_clients)
try:
download = await client.download_blob()
except ResourceNotFoundError:
raise ObjNotFoundError(obj_id) from None
else:
data = await download.content_as_bytes()
decompressor = decompressors[self.compression]()
ret = decompressor.decompress(data)
if decompressor.unused_data:
raise Error("Corrupt object %s: trailing data found" % hex_obj_id)
return ret
async def _get_async_or_none(self, obj_id, container_clients):
"""Like ``get_async(obj_id)``, but returns None instead of raising
ResourceNotFoundError. Used by ``get_batch`` so other blobs can be returned
even if one is missing."""
try:
return await self._get_async(obj_id, container_clients)
except ObjNotFoundError:
return None
async def _get_batch_async(self, obj_ids):
async with self.get_async_container_clients() as container_clients:
return await asyncio.gather(
*[
self._get_async_or_none(obj_id, container_clients)
for obj_id in obj_ids
]
)
def get_batch(self, obj_ids):
"""Retrieve objects' raw content in bulk from storage, concurrently."""
return call_async(self._get_batch_async, obj_ids)
def check(self, 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)
def delete(self, obj_id):
"""Delete an object."""
super().delete(obj_id) # Check delete permission
hex_obj_id = self._internal_id(obj_id)
client = self.get_blob_client(hex_obj_id)
try:
client.delete_blob()
except ResourceNotFoundError:
raise ObjNotFoundError(obj_id) from None
return True
class PrefixedAzureCloudObjStorage(AzureCloudObjStorage):
"""ObjStorage with azure capabilities, striped by prefix.
accounts is a dict containing entries of the form:
<prefix>: <container_url_for_prefix>
"""
def __init__(
self,
accounts: Dict[str, Union[str, Dict[str, str]]],
compression="gzip",
**kwargs,
):
# shortcut AzureCloudObjStorage __init__
ObjStorage.__init__(self, **kwargs)
self.compression = compression
# Definition sanity check
prefix_lengths = set(len(prefix) for prefix in accounts)
if not len(prefix_lengths) == 1:
raise ValueError(
"Inconsistent prefixes, found lengths %s"
% ", ".join(str(lst) for lst in sorted(prefix_lengths))
)
self.prefix_len = prefix_lengths.pop()
expected_prefixes = set(
"".join(letters)
for letters in product(
set(string.hexdigits.lower()), repeat=self.prefix_len
)
)
missing_prefixes = expected_prefixes - set(accounts)
if missing_prefixes:
raise ValueError(
"Missing prefixes %s" % ", ".join(sorted(missing_prefixes))
)
do_warning = False
self.container_urls = {}
for prefix, container_url in accounts.items():
if isinstance(container_url, dict):
do_warning = True
container_url = get_container_url(
account_name=container_url["account_name"],
account_key=container_url["api_secret_key"],
container_name=container_url["container_name"],
access_policy="full",
)
self.container_urls[prefix] = container_url
if do_warning:
warnings.warn(
"The Azure objstorage account secret key parameters are "
"deprecated, please use container URLs instead.",
DeprecationWarning,
)
def get_container_client(self, hex_obj_id):
"""Get the block_blob_service and container that contains the object with
internal id hex_obj_id
"""
prefix = hex_obj_id[: self.prefix_len]
return ContainerClient.from_container_url(self.container_urls[prefix])
@contextlib.asynccontextmanager
async def get_async_container_clients(self):
# This is equivalent to:
# client1 = AsyncContainerClient.from_container_url(url1)
# ...
# client16 = AsyncContainerClient.from_container_url(url16)
# async with client1, ..., client16:
# yield {prefix1: client1, ..., prefix16: client16}
clients = {
prefix: AsyncContainerClient.from_container_url(url)
for (prefix, url) in self.container_urls.items()
}
async with contextlib.AsyncExitStack() as stack:
for client in clients.values():
await stack.enter_async_context(client)
yield clients
def get_async_blob_client(self, hex_obj_id, container_clients):
"""Get the azure blob client for the given hex obj id and a collection
yielded by ``get_async_container_clients``."""
prefix = hex_obj_id[: self.prefix_len]
return container_clients[prefix].get_blob_client(blob=hex_obj_id)
def get_all_container_clients(self):
"""Get all active container clients"""
# iterate on items() to sort blob services;
# needed to be able to paginate in the list_content() method
yield from (
self.get_container_client(prefix) for prefix in sorted(self.container_urls)
)

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