Package: azure-eventhub-checkpointstoreblob
Azure EventHubs Checkpoint Store client library for Python using Storage BlobsAzure EventHubs Checkpoint Store is used for storing checkpoints while processing events from Azure Event Hubs.
This Checkpoint Store package works as a plug-in package toEventHubConsumerClient. It uses Azure Storage Blob as the persistent store for maintaining checkpoints and partition ownership information.Please note that this is a sync library, for async version of the Azure EventHubs Checkpoint Store client library, please refer toazure-eventhub-checkpointstoreblob-aio.Source code|Package (PyPi)|API reference documentation|Azure Eventhubs documentation|Azure Storage documentationGetting startedPrerequisitesPython2.7, Python 3.6 or later.Microsoft Azure Subscription:To use Azure services, including Azure Event Hubs, you'll need a subscription. If you do not have an existing Azure account, you may sign up for a free trial or use your MSDN subscriber benefits when youcreate an account.Event Hubs namespace with an Event Hub:To interact with Azure Event Hubs, you'll also need to have a namespace and Event Hub  available.  If you are not familiar with creating Azure resources, you may wish to follow the step-by-step guide forcreating an Event Hub using the Azure portal.  There, you can also find detailed instructions for using the Azure CLI, Azure PowerShell, or Azure Resource Manager (ARM) templates to create an Event Hub.Azure Storage Account:You'll need to have an Azure Storage Account and create a Azure Blob Storage Block Container to store the checkpoint data with blobs. You may follow the guidecreating an Azure Block Blob Storage Account.Install the package$ pip install azure-eventhub-checkpointstoreblobKey conceptsCheckpointingCheckpointing is a process by which readers mark or commit their position within a partition event sequence.
Checkpointing is the responsibility of the consumer and occurs on a per-partition basis within a consumer group.
This responsibility means that for each consumer group, each partition reader must keep track of its current position
in the event stream, and can inform the service when it considers the data stream complete. If a reader disconnects from
a partition, when it reconnects it begins reading at the checkpoint that was previously submitted by the last reader of
that partition in that consumer group. When the reader connects, it passes the offset to the event hub to specify the
location at which to start reading. In this way, you can use checkpointing to both mark events as "complete" by
downstream applications, and to provide resiliency if a failover between readers running on different machines occurs.
It is possible to return to older data by specifying a lower offset from this checkpointing process. Through this
mechanism, checkpointing enables both failover resiliency and event stream replay.Offsets & sequence numbersBoth offset & sequence number refer to the position of an event within a partition. You can think of them as a
client-side cursor. The offset is a byte numbering of the event. The offset/sequence number enables an event consumer
(reader) to specify a point in the event stream from which they want to begin reading events. You can specify a
timestamp such that you receive events enqueued only after the given timestamp. Consumers are responsible for
storing their own offset values outside of the Event Hubs service. Within a partition, each event includes an offset,
sequence number and the timestamp of when it was enqueued.ExamplesCreate an Azure EventHubsEventHubConsumerClientConsume events using aBlobCheckpointStoreCreate anEventHubConsumerClientThe easiest way to create aEventHubConsumerClientis to use a connection string.fromazure.eventhubimportEventHubConsumerClienteventhub_client=EventHubConsumerClient.from_connection_string("my_eventhub_namespace_connection_string","my_consumer_group",eventhub_name="my_eventhub")For other ways of creating aEventHubConsumerClient, refer toEventHubs libraryfor more details.Consume events using aBlobCheckpointStoreto do checkpointfromazure.eventhubimportEventHubConsumerClientfromazure.eventhub.extensions.checkpointstoreblobimportBlobCheckpointStoreconnection_str='<< CONNECTION STRING FOR THE EVENT HUBS NAMESPACE >>'consumer_group='<< CONSUMER GROUP >>'eventhub_name='<< NAME OF THE EVENT HUB >>'storage_connection_str='<< CONNECTION STRING OF THE STORAGE >>'container_name='<< STORAGE CONTAINER NAME>>'defon_event(partition_context,event):# Put your code here.partition_context.update_checkpoint(event)# Or update_checkpoint every N events for better performance.defmain():checkpoint_store=BlobCheckpointStore.from_connection_string(storage_connection_str,container_name)client=EventHubConsumerClient.from_connection_string(connection_str,consumer_group,eventhub_name=eventhub_name,checkpoint_store=checkpoint_store,)withclient:client.receive(on_event)if__name__=='__main__':main()UseBlobCheckpointStorewith a different version of Azure Storage Service APISome environments have different versions of Azure Storage Service API.BlobCheckpointStoreby default uses the Storage Service API version 2019-07-07. To use it against a different
version, specifyapi_versionwhen you create theBlobCheckpointStoreobject.TroubleshootingGeneralEnabling logging will be helpful to do trouble shooting.LoggingEnableazure.eventhub.extensions.checkpointstorebloblogger to collect traces from the library.Enableazure.eventhublogger to collect traces from the main azure-eventhub library.Enableazure.eventhub.extensions.checkpointstoreblob._vendor.storagelogger to collect traces from azure storage blob library.Enableuamqplogger to collect traces from the underlying uAMQP library.Enable AMQP frame level trace by settinglogging_enable=Truewhen creating the client.Next stepsMore sample codeGet started with ourEventHubs Checkpoint Store samples.receive_events_using_checkpoint_store.py- EventHubConsumerClient with blob checkpoint store examplereceive_events_using_checkpoint_store_storage_api_version.py- EventHubConsumerClient with blob checkpoint store and storage version exampleDocumentationReference documentation is availablehere.Provide FeedbackIf you encounter any bugs or have suggestions, please file an issue in theIssuessection of the project.ContributingThis project welcomes contributions and suggestions.  Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution. For details, visithttps://cla.microsoft.com.When you submit a pull request, a CLA-bot will automatically determine whether you need to provide a CLA and decorate the PR appropriately (e.g., label, comment). Simply follow the instructions provided by the bot. You will only need to do this once across all repos using our CLA.This project has adopted theMicrosoft Open Source Code of Conduct.
For more information see theCode of Conduct FAQor contactopencode@microsoft.comwith any additional questions or comments.Release History1.1.4 (2021-04-07)This version and all future versions will require Python 2.7 or Python 3.6+, Python 3.5 is no longer supported.New featuresUpdatedlist_ownership,claim_ownership,update_checkpoint,list_checkpointsonBlobCheckpointStoreto support taking**kwargs.1.1.3 (2021-03-09)This version will be the last version to officially support Python 3.5, future versions will require Python 2.7 or Python 3.6+.Bug fixesUpdated vendor azure-storage-blob dependency to v12.7.1.Fixed storage blob authentication failure due to request date header too old (#16192).1.1.2 (2021-01-11)Bug fixesFixed a bug thatBlobCheckpointStore.list_ownershipandBlobCheckpointStore.list_checkpointstriggeringKeyErrordue to reading empty metadata of parent node when working with Data Lake enabled Blob Storage.1.1.1 (2020-09-08)Bug fixesFixed a bug that may gradually slow down retrieving checkpoint data from the storage blob if the storage account "File share soft delete" is enabled. #128361.1.0 (2020-03-09)New featuresParamapi_versionofBlobCheckpointStorenow supports older versions of Azure Storage Service API.1.0.0 (2020-01-13)Stable release. No new features or API changes.1.0.0b6 (2019-12-04)Breaking changesRenamedBlobPartitionManagertoBlobCheckpointStore.Constructor ofBlobCheckpointStorehas been updated to take the storage container details directly rather than an instance ofContainerClient.Afrom_connection_stringconstructor has been added for Blob Storage connection strings.Moduleblobstoragepmis now internal, all imports should be directly fromazure.eventhub.extensions.checkpointstoreblob.BlobCheckpointStorenow has aclose()function for shutting down an HTTP connection pool, additionally the object can be used in a context manager to manage the connection.1.0.0b5 (2019-11-04)New featuresBlobPartitionManagerthat uses Azure Blob Storage Block Blob to store EventProcessor checkpoint data