# --------------------------------------------------------------------------------------------
# Copyright (c) Microsoft Corporation. All rights reserved.
# Licensed under the MIT License. See License.txt in the project root for license information.
# --------------------------------------------------------------------------------------------
from typing import Iterable, Dict, Any, Optional
import logging
from collections import defaultdict
import asyncio
from azure.eventhub.exceptions import OwnershipLostError # type: ignore
from azure.eventhub.aio import CheckpointStore # type: ignore # pylint: disable=no-name-in-module
from azure.core.exceptions import ResourceModifiedError, ResourceExistsError, ResourceNotFoundError # type: ignore
from ._vendor.storage.blob.aio import ContainerClient, BlobClient
from ._vendor.storage.blob._shared.base_client import parse_connection_str
logger = logging.getLogger(__name__)
UPLOAD_DATA = ""
[docs]class BlobCheckpointStore(CheckpointStore):
"""A CheckpointStore that uses Azure Blob Storage to store the partition ownership and checkpoint data.
This class implements methods list_ownership, claim_ownership, update_checkpoint and list_checkpoints that are
defined in class azure.eventhub.aio.CheckpointStore of package azure-eventhub.
:param str blob_account_url:
The URI to the storage account.
:param container_name:
The name of the container for the blobs.
:type container_name: str
:param credential:
The credentials with which to authenticate. This is optional if the
account URL already has a SAS token. The value can be a SAS token string, an account
shared access key, or an instance of a TokenCredentials class from azure.identity.
If the URL already has a SAS token, specifying an explicit credential will take priority.
:keyword str api_version:
The Storage API version to use for requests. Default value is '2019-07-07'.
:keyword str secondary_hostname:
The hostname of the secondary endpoint.
"""
def __init__(self, blob_account_url, container_name, *, credential=None, **kwargs):
# type(str, str, Optional[Any], Any) -> None
self._container_client = kwargs.pop("container_client", None)
if not self._container_client:
api_version = kwargs.pop("api_version", None)
if api_version:
headers = kwargs.get("headers")
if headers:
headers["x-ms-version"] = api_version
else:
kwargs["headers"] = {"x-ms-version": api_version}
self._container_client = ContainerClient(
blob_account_url, container_name, credential=credential, **kwargs
)
self._cached_blob_clients = defaultdict() # type: Dict[str, BlobClient]
[docs] @classmethod
def from_connection_string(
cls, conn_str, container_name, *, credential=None, **kwargs
):
# type: (str, str, Any, Optional[Any], Any) -> BlobCheckpointStore
"""Create BlobCheckpointStore from a storage connection string.
:param str conn_str:
A connection string to an Azure Storage account.
:param container_name:
The container name for the blobs.
:type container_name: str
:param credential:
The credentials with which to authenticate. This is optional if the
account URL already has a SAS token, or the connection string already has shared
access key values. The value can be a SAS token string, an account shared access
key, or an instance of a TokenCredentials class from azure.identity.
Credentials provided here will take precedence over those in the connection string.
:keyword str api_version:
The Storage API version to use for requests. Default value is '2019-07-07'.
:keyword str secondary_hostname:
The hostname of the secondary endpoint.
:returns: A blob checkpoint store.
:rtype: ~azure.eventhub.extensions.checkpointstoreblobaio.BlobCheckpointStore
"""
account_url, secondary, credential = parse_connection_str(conn_str, credential, 'blob')
if 'secondary_hostname' not in kwargs:
kwargs['secondary_hostname'] = secondary
return cls(account_url, container_name, credential=credential, **kwargs)
async def __aenter__(self):
await self._container_client.__aenter__()
return self
async def __aexit__(self, *args):
await self._container_client.__aexit__(*args)
def _get_blob_client(self, blob_name: str) -> BlobClient:
result = self._cached_blob_clients.get(blob_name)
if not result:
result = self._container_client.get_blob_client(blob_name)
self._cached_blob_clients[blob_name] = result
return result
async def _upload_ownership(
self, ownership: Dict[str, Any], metadata: Dict[str, str]
) -> None:
etag = ownership.get("etag")
if etag:
etag_match = {"if_match": etag}
else:
etag_match = {"if_none_match": "*"}
blob_name = "{}/{}/{}/ownership/{}".format(
ownership["fully_qualified_namespace"],
ownership["eventhub_name"],
ownership["consumer_group"],
ownership["partition_id"],
)
blob_name = blob_name.lower()
blob_client = self._get_blob_client(blob_name)
try:
uploaded_blob_properties = await blob_client.set_blob_metadata(metadata, **etag_match)
except ResourceNotFoundError:
logger.info("Upload ownership blob %r because it hasn't existed in the container yet.", blob_name)
uploaded_blob_properties = await blob_client.upload_blob(
data=UPLOAD_DATA, overwrite=True, metadata=metadata, **etag_match
)
ownership["etag"] = uploaded_blob_properties["etag"]
ownership["last_modified_time"] = uploaded_blob_properties[
"last_modified"
].timestamp()
ownership.update(metadata)
async def _claim_one_partition(self, ownership: Dict[str, Any]) -> Dict[str, Any]:
partition_id = ownership["partition_id"]
namespace = ownership["fully_qualified_namespace"]
eventhub_name = ownership["eventhub_name"]
consumer_group = ownership["consumer_group"]
owner_id = ownership["owner_id"]
metadata = {"ownerid": owner_id}
try:
await self._upload_ownership(ownership, metadata)
return ownership
except (ResourceModifiedError, ResourceExistsError):
logger.info(
"EventProcessor instance %r of namespace %r eventhub %r consumer group %r "
"lost ownership to partition %r",
owner_id,
namespace,
eventhub_name,
consumer_group,
partition_id,
)
raise OwnershipLostError()
except Exception as error: # pylint:disable=broad-except
logger.warning(
"An exception occurred when EventProcessor instance %r claim_ownership for "
"namespace %r eventhub %r consumer group %r partition %r. "
"The ownership is now lost. Exception "
"is %r",
owner_id,
namespace,
eventhub_name,
consumer_group,
partition_id,
error,
)
return ownership # Keep the ownership if an unexpected error happens
[docs] async def list_ownership(
self, fully_qualified_namespace: str, eventhub_name: str, consumer_group: str
) -> Iterable[Dict[str, Any]]:
"""Retrieves a complete ownership list from the storage blob.
:param str fully_qualified_namespace: The fully qualified namespace that the Event Hub belongs to.
The format is like "<namespace>.servicebus.windows.net".
:param str eventhub_name: The name of the specific Event Hub the partition ownerships are associated with,
relative to the Event Hubs namespace that contains it.
:param str consumer_group: The name of the consumer group the ownerships are associated with.
:rtype: Iterable[Dict[str, Any]], Iterable of dictionaries containing partition ownership information:
- `fully_qualified_namespace` (str): The fully qualified namespace that the Event Hub belongs to.
The format is like "<namespace>.servicebus.windows.net".
- `eventhub_name` (str): The name of the specific Event Hub the checkpoint is associated with,
relative to the Event Hubs namespace that contains it.
- `consumer_group` (str): The name of the consumer group the ownership are associated with.
- `partition_id` (str): The partition ID which the checkpoint is created for.
- `owner_id` (str): A UUID representing the current owner of this partition.
- `last_modified_time` (UTC datetime.datetime): The last time this ownership was claimed.
- `etag` (str): The Etag value for the last time this ownership was modified. Optional depending
on storage implementation.
"""
try:
blob_prefix = "{}/{}/{}/ownership/".format(
fully_qualified_namespace, eventhub_name, consumer_group
)
blobs = self._container_client.list_blobs(
name_starts_with=blob_prefix.lower(), include=["metadata"]
)
result = []
async for blob in blobs:
ownership = {
"fully_qualified_namespace": fully_qualified_namespace,
"eventhub_name": eventhub_name,
"consumer_group": consumer_group,
"partition_id": blob.name.split("/")[-1],
"owner_id": blob.metadata["ownerid"],
"etag": blob.etag,
"last_modified_time": blob.last_modified.timestamp()
if blob.last_modified
else None,
}
result.append(ownership)
return result
except Exception as error: # pylint:disable=broad-except
logger.warning(
"An exception occurred during list_ownership for "
"namespace %r eventhub %r consumer group %r. "
"Exception is %r",
fully_qualified_namespace,
eventhub_name,
consumer_group,
error,
)
raise
[docs] async def claim_ownership(
self, ownership_list: Iterable[Dict[str, Any]]
) -> Iterable[Dict[str, Any]]:
"""Tries to claim ownership for a list of specified partitions.
:param Iterable[Dict[str,Any]] ownership_list: Iterable of dictionaries containing all the ownerships to claim.
:rtype: Iterable[Dict[str,Any]], Iterable of dictionaries containing partition ownership information:
- `fully_qualified_namespace` (str): The fully qualified namespace that the Event Hub belongs to.
The format is like "<namespace>.servicebus.windows.net".
- `eventhub_name` (str): The name of the specific Event Hub the checkpoint is associated with,
relative to the Event Hubs namespace that contains it.
- `consumer_group` (str): The name of the consumer group the ownership are associated with.
- `partition_id` (str): The partition ID which the checkpoint is created for.
- `owner_id` (str): A UUID representing the owner attempting to claim this partition.
- `last_modified_time` (UTC datetime.datetime): The last time this ownership was claimed.
- `etag` (str): The Etag value for the last time this ownership was modified. Optional depending
on storage implementation.
"""
results = await asyncio.gather(
*[self._claim_one_partition(x) for x in ownership_list],
return_exceptions=True
)
return [
ownership for ownership in results if not isinstance(ownership, Exception)
]
[docs] async def update_checkpoint(self, checkpoint: Dict[str, Any]) -> None:
"""Updates the checkpoint using the given information for the offset, associated partition and
consumer group in the storage blob.
Note: If you plan to implement a custom checkpoint store with the intention of running between
cross-language EventHubs SDKs, it is recommended to persist the offset value as an integer.
:param Dict[str,Any] checkpoint: A dict containing checkpoint information:
- `fully_qualified_namespace` (str): The fully qualified namespace that the Event Hub belongs to.
The format is like "<namespace>.servicebus.windows.net".
- `eventhub_name` (str): The name of the specific Event Hub the checkpoint is associated with,
relative to the Event Hubs namespace that contains it.
- `consumer_group` (str): The name of the consumer group the checkpoint is associated with.
- `partition_id` (str): The partition ID which the checkpoint is created for.
- `sequence_number` (int): The sequence number of the :class:`EventData<azure.eventhub.EventData>`
the new checkpoint will be associated with.
- `offset` (str): The offset of the :class:`EventData<azure.eventhub.EventData>`
the new checkpoint will be associated with.
:rtype: None
"""
metadata = {
"offset": str(checkpoint["offset"]),
"sequencenumber": str(checkpoint["sequence_number"]),
}
blob_name = "{}/{}/{}/checkpoint/{}".format(
checkpoint["fully_qualified_namespace"],
checkpoint["eventhub_name"],
checkpoint["consumer_group"],
checkpoint["partition_id"],
)
blob_name = blob_name.lower()
blob_client = self._get_blob_client(blob_name)
try:
await blob_client.set_blob_metadata(metadata)
except ResourceNotFoundError:
logger.info("Upload checkpoint blob %r because it hasn't existed in the container yet.", blob_name)
await blob_client.upload_blob(
data=UPLOAD_DATA, overwrite=True, metadata=metadata
)
[docs] async def list_checkpoints(
self, fully_qualified_namespace, eventhub_name, consumer_group
):
"""List the updated checkpoints from the storage blob.
:param str fully_qualified_namespace: The fully qualified namespace that the Event Hub belongs to.
The format is like "<namespace>.servicebus.windows.net".
:param str eventhub_name: The name of the specific Event Hub the checkpoints are associated with, relative to
the Event Hubs namespace that contains it.
:param str consumer_group: The name of the consumer group the checkpoints are associated with.
:rtype: Iterable[Dict[str,Any]], Iterable of dictionaries containing partition checkpoint information:
- `fully_qualified_namespace` (str): The fully qualified namespace that the Event Hub belongs to.
The format is like "<namespace>.servicebus.windows.net".
- `eventhub_name` (str): The name of the specific Event Hub the checkpoints are associated with,
relative to the Event Hubs namespace that contains it.
- `consumer_group` (str): The name of the consumer group the checkpoints are associated with.
- `partition_id` (str): The partition ID which the checkpoint is created for.
- `sequence_number` (int): The sequence number of the :class:`EventData<azure.eventhub.EventData>`.
- `offset` (str): The offset of the :class:`EventData<azure.eventhub.EventData>`.
"""
blob_prefix = "{}/{}/{}/checkpoint/".format(
fully_qualified_namespace, eventhub_name, consumer_group
)
blobs = self._container_client.list_blobs(
name_starts_with=blob_prefix.lower(), include=["metadata"]
)
result = []
async for blob in blobs:
metadata = blob.metadata
checkpoint = {
"fully_qualified_namespace": fully_qualified_namespace,
"eventhub_name": eventhub_name,
"consumer_group": consumer_group,
"partition_id": blob.name.split("/")[-1],
"offset": str(metadata["offset"]),
"sequence_number": int(metadata["sequencenumber"]),
}
result.append(checkpoint)
return result
[docs] async def close(self) -> None:
"""Close an open HTTP session and connection."""
return await self.__aexit__()