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Cloud Storage Sink Connector for Pulsar

The Cloud Storage sink connector supports exporting data from Pulsar topics to cloud storage (such as AWS S3 and Google GCS) either in Avro, JSON, Parquet or other formats. According to your environment, the Cloud Storage sink connector can guarantee exactly-once support for exporting data to cloud storage.

Installation

There are two ways to install the Cloud Storage sink connector.

  • Install the the Cloud Storage sink connector through the NAR file.
  • Install the the Cloud Storage sink connector from the source code.

To build the the Cloud Storage sink connector from the source code, follow these steps.

  1. Clone the project from GitHub to your local.

    git clone https://github.com/streamnative/pulsar-io-cloud-storage.git
cd pulsar-io-cloud-storage

  2. Build the project.

    mvn clean install -DskipTests

    You can find the NAR file in the following directory.

    ./pulsar-io-cloud-storage/target/pulsar-io-cloud-storage-${version}.nar

Configuration

The Cloud Storage sink connector supports the following properties.

Cloud Storage sink connector configuration

Storage Provider: AWS S3

Name Type Required Default Description
provider String True null The Cloud Storage type, such as aws-s3,s3v2(s3v2 uses the AWS client but not the JCloud client).
accessKeyId String True null The Cloud Storage access key ID. It requires permission to write objects.
secretAccessKey String True null The Cloud Storage secret access key.
role String False null The Cloud Storage role.
roleSessionName String False null The Cloud Storage role session name.
endpoint String True null The Cloud Storage endpoint.
bucket String True null The Cloud Storage bucket.
formatType String False "json" The data format type. Available options are JSON, Avro, Bytes, or Parquet. By default, it is set to JSON.
partitionerType String False "partition" The partitioning type. It can be configured by topic partitions or by time. By default, the partition type is configured by topic partitions.
timePartitionPattern String 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 "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.
partitionerUseIndexAsOffset Boolean 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.
batchSize int False 10 The number of records submitted in batch.
batchTimeMs long False 1000 The interval for batch submission.
maxBatchBytes long False 10000000 The maximum number of bytes in a batch.
sliceTopicPartitionPath Boolean False false When it is set to true, split the partitioned topic name into separate folders in the bucket path.
withMetadata Boolean False false Save message attributes to metadata.
useHumanReadableMessageId Boolean 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.
withTopicPartitionNumber Boolean False true When it is set to true, include the topic partition number to the object path.
bytesFormatTypeSeparator String 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.
pendingQueueSize int False 10 The number of records buffered in queue. By default, it is equal tobatchSize. You can set it manually.
useHumanReadableSchemaVersion Boolean 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.
skipFailedMessages Boolean 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.
pathPrefix String 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/.
avroCodec String False snappy Compression codec used when formatType=avro. Available compression types are: null (no compression), deflate, bzip2, xz, zstandard, snappy.
parquetCodec String False gzip Compression codec used when formatType=parquet. Available compression types are: null (no compression), snappy, gzip, lzo, brotli, lz4, zstd.
jsonAllowNaN Boolean 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.

Storage Provider: Google Cloud Storage

Name Type Required Default Description
provider String True null The Cloud Storage type. Google cloud storage only supports the google-cloud-storage provider.
gcsServiceAccountKeyFilePath String False "" Path to the GCS credentials file. If empty, the credentials file are read from the GOOGLE_APPLICATION_CREDENTIALS environment variable.
gcsServiceAccountKeyFileContent String False "" The contents of the JSON service key file. If empty, credentials are read from gcsServiceAccountKeyFilePath file.
bucket String True null The Cloud Storage bucket.
formatType String False "json" The data format type. Available options are JSON, Avro, Bytes, or Parquet. By default, it is set to JSON.
partitionerType String False "partition" The partitioning type. It can be configured by topic partitions or by time. By default, the partition type is configured by topic partitions.
timePartitionPattern String 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 "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.
partitionerUseIndexAsOffset Boolean 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.
batchSize int False 10 The number of records submitted in batch.
batchTimeMs long False 1000 The interval for batch submission.
maxBatchBytes long False 10000000 The maximum number of bytes in a batch.
sliceTopicPartitionPath Boolean False false When it is set to true, split the partitioned topic name into separate folders in the bucket path.
withMetadata Boolean False false Save message attributes to metadata.
useHumanReadableMessageId Boolean 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.
withTopicPartitionNumber Boolean False true When it is set to true, include the topic partition number to the object path.
bytesFormatTypeSeparator String 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.
pendingQueueSize int False 10 The number of records buffered in queue. By default, it is equal to batchSize. You can set it manually.
useHumanReadableSchemaVersion Boolean 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.
skipFailedMessages Boolean 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.
pathPrefix String 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/.
avroCodec String False snappy Compression codec used when formatType=avro. Available compression types are: null (no compression), deflate, bzip2, xz, zstandard, snappy.
parquetCodec String False gzip Compression codec used when formatType=parquet. Available compression types are: null (no compression), snappy, gzip, lzo, brotli, lz4, zstd.
jsonAllowNaN Boolean 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.

Storage Provider: Azure Blob Storage

Name Type Required Default Description
provider String True null The Cloud Storage type. Azure Blob Storage only supports the azure-blob-storage provider.
azureStorageAccountSASToken String True "" The Azure Blob Storage account SAS token. Required when authenticating via SAS token.
azureStorageAccountName String True "" The Azure Blob Storage account name. Required when authenticating via account name and account key.
azureStorageAccountKey String True "" The Azure Blob Storage account key. Required when authenticating via account name and account key.
azureStorageAccountConnectionString String True "" The Azure Blob Storage connection string. Required when authenticating via connection string.
endpoint String True null The Azure Blob Storage endpoint.
bucket String True null The Cloud Storage bucket.
formatType String False "json" The data format type. Available options are JSON, Avro, Bytes, or Parquet. By default, it is set to JSON.
partitionerType String False "partition" The partitioning type. It can be configured by topic partitions or by time. By default, the partition type is configured by topic partitions.
timePartitionPattern String 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 "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.
partitionerUseIndexAsOffset Boolean 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.
batchSize int False 10 The number of records submitted in batch.
batchTimeMs long False 1000 The interval for batch submission.
maxBatchBytes long False 10000000 The maximum number of bytes in a batch.
sliceTopicPartitionPath Boolean False false When it is set to true, split the partitioned topic name into separate folders in the bucket path.
withMetadata Boolean False false Save message attributes to metadata.
useHumanReadableMessageId Boolean 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.
withTopicPartitionNumber Boolean False true When it is set to true, include the topic partition number to the object path.
bytesFormatTypeSeparator String 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.
pendingQueueSize int False 10 The number of records buffered in queue. By default, it is equal to batchSize. You can set it manually.
useHumanReadableSchemaVersion Boolean 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.
skipFailedMessages Boolean 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.
pathPrefix String 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/.
avroCodec String False snappy Compression codec used when formatType=avro. Available compression types are: null (no compression), deflate, bzip2, xz, zstandard, snappy.
parquetCodec String False gzip Compression codec used when formatType=parquet. Available compression types are: null (no compression), snappy, gzip, lzo, brotli, lz4, zstd.
jsonAllowNaN Boolean 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.

Configure Cloud Storage sink connector

Before using the Cloud Storage sink connector, you need to create a configuration file through one of the following methods.

  • JSON

    {
   "tenant": "public",
   "namespace": "default",
   "name": "cloud-storage-sink",
   "inputs": [
      "user-avro-topic"
   ],
   "archive": "connectors/pulsar-io-cloud-storage-0.0.1.nar",
   "parallelism": 1,
   "configs": {
      "provider": "aws-s3",
      "accessKeyId": "accessKeyId",
      "secretAccessKey": "secretAccessKey",
      "role": "none",
      "roleSessionName": "none",
      "bucket": "testBucket",
      "region": "local",
      "endpoint": "us-standard",
      "formatType": "parquet",
      "partitionerType": "time",
      "timePartitionPattern": "yyyy-MM-dd",
      "timePartitionDuration": "1d",
      "batchSize": 10,
      "batchTimeMs": 1000
   }
}

  • YAML

    tenant: "public"
namespace: "default"
name: "Cloud Storage-sink"
inputs: 
  - "user-avro-topic"
archive: "connectors/pulsar-io-cloud-storage-0.0.1.nar"
parallelism: 1

configs:
  provider: "aws-s3",
  accessKeyId: "accessKeyId"
  secretAccessKey: "secretAccessKey"
  role: "none"
  roleSessionName: "none"
  bucket: "testBucket"
  region: "local"
  endpoint: "us-standard"
  formatType: "parquet"
  partitionerType: "time"
  timePartitionPattern: "yyyy-MM-dd"
  timePartitionDuration: "1d"
  batchSize: 10
  batchTimeMs: 1000

Data format types

Cloud 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;
}

By default, when the connector receives a message with a non-supported schema type, the connector will fail the message. If you want to skip the non-supported messages, you can set skipFailedMessages to true.

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 Cloud Storage and there is a dead-letter topic, the connector will send the message to the dead-letter topic.

Usage

  1. Prepare the AWS Cloud Storage service. In this example, we use Cloud Storagemock as an example.

    docker pull apachepulsar/s3mock:latest
docker run -p 9090:9090 -e initialBuckets=pulsar-integtest apachepulsar/s3mock:latest

  2. Put the pulsar-io-cloud-storage-2.5.1.nar in the Pulsar connector catalog.

    cp pulsar-io-cloud-storage-2.5.1.nar $PULSAR_HOME/connectors/pulsar-io-cloud-storage-2.5.1.nar

  3. Start Pulsar in the standalone mode.

    $PULSAR_HOME/bin/pulsar standalone

  4. Run the Cloud Storage sink connector locally.

    $PULSAR_HOME/bin/pulsar-admin sink localrun --sink-config-file cloud-storage-sink-config.yaml

  5. Send Pulsar messages. Currently, Avro or JSON mode supports formatType json, avro, parquet. No schema mode can only use bytes formatType.

      try (
             PulsarClient pulsarClient = PulsarClient.builder()
                     .serviceUrl("pulsar://localhost:6650")
                     .build();
             Producer<TestRecord> producer = pulsarClient.newProducer(Schema.AVRO(TestRecord.class))
                     .topic("public/default/test-parquet-avro")
                     .create();
             ) {
             List<TestRecord> testRecords = Arrays.asList(
                     new TestRecord("key1", 1, null),
                     new TestRecord("key2", 1, new TestRecord.TestSubRecord("aaa"))
             );
             for (TestRecord record : testRecords) {
                 producer.send(record);
             }
         }

  6. Validate Cloud Storage data.

    To get the path, you can use the jclould to verify the file, as shown below.

    Properties overrides = new Properties();
overrides.put(“jclouds.s3.virtual-host-buckets”, “false”);
BlobStoreContext blobStoreContext = ContextBuilder.newBuilder(“aws-s3”)
        .credentials(
                “accessKeyId”,
                “secretAccessKey”
        )
        .endpoint(“http://localhost:9090”) // replace to s3mock url
        .overrides(overrides)
        .buildView(BlobStoreContext.class);
BlobStore blobStore = blobStoreContext.getBlobStore();
final long sequenceId = FunctionCommon.getSequenceId(message.getMessageId());
final String path = “public/default/test-parquet-avro” + File.separator + “2020-09-14" + File.separator + sequenceId + “.parquet”;
final boolean blobExists = blobStore.blobExists(“testBucket”, path);
Assert.assertTrue(“the sink record does not exist”, blobExists);

    You can find the data in your testBucket bucket. The path is something like public/default/test-parquet-avro/2020-09-14/1234.parquet. The path consists of three parts, the basic part of the topic, partition information, and format suffix.

    • Basic part of topic: public/default/test-parquet-avro/ This part consists of the name of the tenant, namespace, and the input topic.
    • Partition information: 2020-09-14/${messageSequenceId} The date is generated based on the partitionerType parameter in the configuration. And the ${messageSequenceId} is generated by FunctionCommon.getSequenceId(message.getMessageId()).
    • Format suffix: .parquet This part is generated based on the formatType parameter in the configuration.

Permissions

AWS S3 permission policies

The suggested permission policies for AWS S3 are:

  • s3:AbortMultipartUpload
  • s3:CreateBucket
  • s3:PutObject

If you do not want to provide region in the configuration, you should enable s3:GetBucketLocation permission policy as well.

Troubleshooting

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 cloud 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.