Azure Blob Storage - StreamNative Documentation

This connector is available as a built-in connector on StreamNative Cloud.

The Azure Blob Storage sink connector pulls data from Pulsar topics and persists data to Azure Blob Storage containers.

Quick start

Prerequisites

The prerequisites for connecting an Azure Blob Storage sink connector to external systems include:

Create Blob Storage container in Azure Cloud.
Get Storage account Connection string.

1. Create a connector

The following command shows how to use pulsarctl to create a builtin connector. If you want to create a non-builtin connector, you need to replace --sink-type cloud-storage-azure-blob with --archive /path/to/pulsar-io-cloud-storage.nar. You can find the button to download the nar package at the beginning of the document.

If you are a StreamNative Cloud user, you need set up your environment first.

pulsarctl sinks create \
  --sink-type cloud-storage-azure-blob \
  --name azure-blob-sink \
  --tenant public \
  --namespace default \
  --inputs "Your topic name" \
  --parallelism 1 \
  --sink-config \
  '{
    "azureStorageAccountConnectionString": "Your azure blob storage account connection string",
    "provider": "azure-blob-storage",
    "bucket": "Your container name",
    "formatType": "json",
    "partitionerType": "PARTITION"
  }'

The --sink-config is the minimum necessary configuration for starting this connector, and it is a JSON string. You need to substitute the relevant parameters with your own. If you want to configure more parameters, see Configuration Properties for reference.

You can also choose to use a variety of other tools to create a connector:

pulsar-admin: The command arguments for pulsar-admin are similar to those of pulsarctl. You can find an example for StreamNative Cloud Doc.
RestAPI: You can find an example for StreamNative Cloud Doc.
Terraform: You can find an example for StreamNative Cloud Doc.
Function Mesh: The docker image can be found at the beginning of the document.

2. Send messages to the topic

If your connector is created on StreamNative Cloud, you need to authenticate your clients. See Build applications using Pulsar clients for more information.

    public static void main(String[] args) throws Exception {
        PulsarClient client = PulsarClient.builder()
                             .serviceUrl("{{Your Pulsar URL}}")
                             .build();


        Producer<String> producer = client.newProducer(Schema.STRING)
                .topic("{{Your topic name}}")
                .create();

        for (int i = 0; i < 10; i++) {
            // JSON string containing a single character
            String message = "{\"test-message\": \"test-value\"}";
            producer.send(message);
        }

        producer.close();
        client.close();
    }

3. Display data on Azure Blob Storage console

You can see the object at public/default/{{Your topic name}}-partition-0/xxxx.json on the Azure Blob Storage console. Download and open it, the content is:

`{"test-message":"test-value"}`
`{"test-message":"test-value"}`
`{"test-message":"test-value"}`
`{"test-message":"test-value"}`
`{"test-message":"test-value"}`
`{"test-message":"test-value"}`
`{"test-message":"test-value"}`
`{"test-message":"test-value"}`
`{"test-message":"test-value"}`
`{"test-message":"test-value"}`

Configuration Properties

Before using the Azure Blob Storage sink connector, you need to configure it. This table outlines the properties and the descriptions.

Name	Type	Required	Sensitive	Default	Description
`provider`	String	True	false	null	The Cloud Storage type, Azure Blob Storage only supports the `azure-blob-storage` provider.
`bucket`	String	True	false	null	The Azure Blob Storage container name.
`formatType`	String	True	false	”json”	The data format type. Available options are `json`, `avro`, `bytes`, or `parquet`. By default, it is set to `json`.
`partitionerType`	String	False	false	null	The partitioning type. It can be configured by topic `PARTITION` or `TIME`. By default, the partition type is configured by topic partitions.
`azureStorageAccountConnectionString`	String	False	true	""	The Azure Blob Storage connection string. Required when authenticating via connection string.
`azureStorageAccountSASToken`	String	False	true	""	The Azure Blob Storage account SAS token. Required when authenticating via SAS token.
`azureStorageAccountName`	String	False	true	""	The Azure Blob Storage account name. Required when authenticating via account name and account key.
`azureStorageAccountKey`	String	False	true	""	The Azure Blob Storage account key. Required when authenticating via account name and account key.
`endpoint`	String	False	false	null	The Azure Blob Storage endpoint. Required when authenticating via account name or SAS token.
`timePartitionPattern`	String	False	false	”yyyy-MM-dd”	The format pattern of the time-based partitioning. For details, refer to the Java date and time format.
`timePartitionDuration`	String	False	false	”86400000”	The time interval for time-based partitioning. Support formatted interval string, such as `30d`, `24h`, `30m`, `10s`, and also support number in milliseconds precision, such as `86400000` refers to `24h` or `1d`.
`pathPrefix`	String	False	false	false	If it is set, the output files are stored in a folder under the given bucket path. The `pathPrefix` must be in the format of `xx/xxx/`.
`partitionerWithTopicName`	Boolean	False	false	true	Indicates whether to include the topic name in the file path. Default is true. If not included, the path like: `pathPrefix/24.45.0.json`
`partitionerUseIndexAsOffset`	Boolean	False	false	false	Whether to use the Pulsar’s message index as offset or the record sequence. It’s recommended if the incoming messages may be batched. The brokers may or not expose the index metadata and, if it’s not present on the record, the sequence will be used. See PIP-70 for more details.
`withTopicPartitionNumber`	Boolean	False	false	true	When it is set to `true`, include the topic partition number to the object path.
`sliceTopicPartitionPath`	Boolean	False	false	false	When it is set to `true`, split the partitioned topic name into separate folders in the bucket path.
`batchSize`	int	False	false	10	The number of records submitted in batch.
`batchTimeMs`	long	False	false	1000	The interval for batch submission.
`maxBatchBytes`	long	False	false	10000000	The maximum number of bytes in a batch.
`batchModel`	Enum	False	false	BLEND	Determines how records are batched. Options: `BLEND`, `PARTITIONED`. The BLEND which combines all topic records into a single batch, optimizing for throughput, and PARTITIONED which batches records separately for each topic, maintaining topic-level separation. Note: When set to PARTITIONED, the connector will cache data up to the size of the number of subscribed topics multiplied by maxBatchBytes. This means you need to anticipate the connector’s memory requirements in advance.
`skipFailedMessages`	Boolean	False	false	false	Configure whether to skip a message which it fails to be processed. If it is set to `true`, the connector will skip the failed messages by `ack` it. Otherwise, the connector will `fail` the message.
`withMetadata`	Boolean	False	false	false	Save message attributes to metadata.
`useHumanReadableMessageId`	Boolean	False	false	false	Use a human-readable format string for messageId in message metadata. The messageId is in a format like `ledgerId:entryId:partitionIndex:batchIndex`. Otherwise, the messageId is a Hex-encoded string.
`useHumanReadableSchemaVersion`	Boolean	False	false	false	Use a human-readable format string for the schema version in the message metadata. If it is set to `true`, the schema version is in plain string format. Otherwise, the schema version is in hex-encoded string format.
`includeTopicToMetadata`	Boolean	False	false	false	Include the topic name to the metadata.
`includePublishTimeToMetadata`	Boolean	False	false	false	Include the message publish time to the metadata as a timestamp.
`includeMessageKeyToMetadata`	Boolean	False	false	false	Include the message key to the metadata as a string.
`avroCodec`	String	False	false	snappy	Compression codec used when formatType=`avro`. Available compression types are: none (no compression), deflate, bzip2, xz, zstandard, snappy.
`parquetCodec`	String	False	false	gzip	Compression codec used when formatType=`parquet`. Available compression types are: none (no compression), snappy, gzip, lzo, brotli, lz4, zstd.
`jsonAllowNaN`	Boolean	False	false	false	Recognize ‘NaN’, ‘INF’, ‘-INF’ as legal floating number values when formatType=`json`. Since JSON specification does not allow such values this is a non-standard feature and disabled by default.
`bytesFormatTypeSeparator`	String	False	false	”0x10”	It is inserted between records for the `formatType` of bytes. By default, it is set to ‘0x10’. An input record that contains the line separator looks like multiple records in the output object.

There are three methods to authenticate with Azure Blob Storage:

azureStorageAccountConnectionString: This method involves using the Azure Blob Storage connection string for authentication. It’s the simplest method as it only requires the connection string.
azureStorageAccountSASToken: This method uses a Shared Access Signature (SAS) token for the Azure Blob Storage account. When using this method, you must also set the endpoint.
azureStorageAccountName and azureStorageAccountKey: This method uses the Azure Blob Storage account name and account key for authentication. Similar to the SAS token method, you must also set the endpoint when using this method.

Advanced features

Data format types

Azure Blob Storage Sink Connector provides multiple output format options, including JSON, Avro, Bytes, or Parquet. The default format is JSON. With current implementation, there are some limitations for different formats: This table lists the Pulsar Schema types supported by the writers.

Pulsar Schema	Writer: Avro	Writer: JSON	Writer: Parquet	Writer: Bytes
Primitive	✗	✔ *	✗	✔
Avro	✔	✔	✔	✔
Json	✔	✔	✔	✔
Protobuf **	✔	✔	✔	✔
ProtobufNative	✔ ***	✗	✔	✔

*: The JSON writer will try to convert the data with a String or Bytes schema to JSON-format data if convertable. **: The Protobuf schema is based on the Avro schema. It uses Avro as an intermediate format, so it may not provide the best effort conversion. ***: The ProtobufNative record holds the Protobuf descriptor and the message. When writing to Avro format, the connector uses avro-protobuf to do the conversion.

This table lists the support of withMetadata configurations for different writer formats:

Writer Format	`withMetadata`
Avro	✔
JSON	✔
Parquet	✔ *
Bytes	✗

*: When using Parquet with PROTOBUF_NATIVE format, the connector will write the messages with DynamicMessage format. When withMetadata is set to true, the connector will add __message_metadata__ to the messages with PulsarIOCSCProtobufMessageMetadata format. For example, if a message User has the following schema:
syntax = "proto3";
message User {
 string name = 1;
 int32 age = 2;
}
When withMetadata is set to true, the connector will write the message DynamicMessage with the following schema:
syntax = "proto3";
message PulsarIOCSCProtobufMessageMetadata {
 map<string, string> properties = 1;
 string schema_version = 2;
 string message_id = 3;
}
message User {
 string name = 1;
 int32 age = 2;
 PulsarIOCSCProtobufMessageMetadata __message_metadata__ = 3;
}

Dead-letter topics

To use a dead-letter topic, you need to set skipFailedMessages to false, and set --max-redeliver-count and --dead-letter-topic when submit the connector with the pulsar-admin CLI tool. For more info about dead-letter topics, see the Pulsar documentation. If a message fails to be sent to the Azure Blob Storage and there is a dead-letter topic, the connector will send the message to the dead-letter topic.

Sink flushing only after batchTimeMs elapses

There is a scenario where the sink is only flushing whenever the batchTimeMs has elapsed, even though there are many messages waiting to be processed. The reason for this is that the sink will only acknowledge messages after they are flushed to the Azure Blob Storage but the broker stops sending messages when it reaches a certain limit of unacknowledged messages. If this limit is lower or close to batchSize, the sink never receives enough messages to trigger a flush based on the amount of messages. In this case please ensure the maxUnackedMessagesPerConsumer set in the broker configuration is sufficiently larger than the batchSize setting of the sink.

Partitioner Type

There are two types of partitioner:

PARTITION: This is the default partitioning method based on Pulsar partitions. In other words, data is partitioned according to the pre-existing partitions in Pulsar topics. For instance, a message for the topic public/default/my-topic-partition-0 would be directed to the file public/default/my-topic-partition-0/xxx.json, where xxx signifies the earliest messageId(Format: ledgerId.entryId.batchIndex)/offset(Enable config: partitionerUseIndexAsOffset) in this file.
TIME: Data is partitioned according to the time it was flushed. Using the previous message as an example, if it was received on 2023-12-20, it would be directed to public/default/my-topic-partition-0/2023-12-20/xxx.json, where xxx also denotes the earliest messageId(Format: ledgerId.entryId.batchIndex)/offset(Enable config: partitionerUseIndexAsOffset) in this file.

Sources

Sinks

Azure blob storage sink

Quick start

Prerequisites

1. Create a connector

2. Send messages to the topic

3. Display data on Azure Blob Storage console

Configuration Properties

Advanced features

Data format types

Dead-letter topics

Sink flushing only after batchTimeMs elapses

Partitioner Type

​Quick start

​Prerequisites

​1. Create a connector

​2. Send messages to the topic

​3. Display data on Azure Blob Storage console

​Configuration Properties

​Advanced features

​Data format types

​Dead-letter topics

​Sink flushing only after batchTimeMs elapses

​Partitioner Type

Quick start

Prerequisites

1. Create a connector

2. Send messages to the topic

3. Display data on Azure Blob Storage console

Configuration Properties

Advanced features

Data format types

Dead-letter topics

Sink flushing only after batchTimeMs elapses

Partitioner Type