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Use AWS S3 offloader with Pulsar

This chapter guides you through every step of installing and configuring the AWS S3 offloader and using it with Pulsar.

Installation​

Follow the steps below to install the AWS S3 offloader.

Prerequisite​

  • Pulsar: 2.4.2 or later versions

Step​

This example uses Pulsar 2.5.1.

  1. Download the Pulsar tarball using one of the following ways:


    wget https://archive.apache.org/dist/pulsar/pulsar-2.5.1/apache-pulsar-2.5.1-bin.tar.gz

  2. Download and untar the Pulsar offloaders package.


    wget https://downloads.apache.org/pulsar/pulsar-2.5.1/apache-pulsar-offloaders-2.5.1-bin.tar.gz
    tar xvfz apache-pulsar-offloaders-2.5.1-bin.tar.gz

  3. Copy the Pulsar offloaders as offloaders in the Pulsar directory.


    mv apache-pulsar-offloaders-2.5.1/offloaders apache-pulsar-2.5.1/offloaders

    ls offloaders

    Output

    As shown from the output, Pulsar uses Apache jclouds to support AWS S3 and GCS for long term storage.


    tiered-storage-file-system-2.5.1.nar
    tiered-storage-jcloud-2.5.1.nar

    note
    • If you are running Pulsar in a bare metal cluster, make sure that offloaders tarball is unzipped in every broker's Pulsar directory.
    • If you are running Pulsar in Docker or deploying Pulsar using a Docker image (such as K8s and DCOS), you can use the apachepulsar/pulsar-all image instead of the apachepulsar/pulsar image. apachepulsar/pulsar-all image has already bundled tiered storage offloaders.

Configuration​

note

Before offloading data from BookKeeper to AWS S3, you need to configure some properties of the AWS S3 offload driver.

Besides, you can also configure the AWS S3 offloader to run it automatically or trigger it manually.

Configure AWS S3 offloader driver​

You can configure the AWS S3 offloader driver in the configuration file broker.conf or standalone.conf.

  • Required configurations are as below.

    Required configurationDescriptionExample value
    managedLedgerOffloadDriverOffloader driver name, which is case-insensitive.

    Note: there is a third driver type, S3, which is identical to AWS S3, though S3 requires that you specify an endpoint URL using s3ManagedLedgerOffloadServiceEndpoint. This is useful if using an S3 compatible data store other than AWS S3.    		aws-s3
    offloadersDirectoryOffloader directoryoffloaders
    s3ManagedLedgerOffloadBucketBucketpulsar-topic-offload

  • Optional configurations are as below.

    OptionalDescriptionExample value
    s3ManagedLedgerOffloadRegionBucket region

    Note: before specifying a value for this parameter, you need to set the following configurations. Otherwise, you might get an error.

    - Set s3ManagedLedgerOffloadServiceEndpoint.

    Example
    s3ManagedLedgerOffloadServiceEndpoint=https://s3.YOUR_REGION.amazonaws.com

    - Grant GetBucketLocation permission to a user.

    For how to grant GetBucketLocation permission to a user, see here.    		eu-west-3
    s3ManagedLedgerOffloadReadBufferSizeInBytesSize of block read1 MB
    s3ManagedLedgerOffloadMaxBlockSizeInBytesSize of block write64 MB
    managedLedgerMinLedgerRolloverTimeMinutesMinimum time between ledger rollover for a topic

    Note: it is not recommended that you set this configuration in the production environment.    		2
    managedLedgerMaxEntriesPerLedgerMaximum number of entries to append to a ledger before triggering a rollover.

    Note: it is not recommended that you set this configuration in the production environment.    		5000

Bucket (required)​

A bucket is a basic container that holds your data. Everything you store in AWS S3 must be contained in a bucket. You can use a bucket to organize your data and control access to your data, but unlike directory and folder, you cannot nest a bucket.

Example​

This example names the bucket as pulsar-topic-offload.


s3ManagedLedgerOffloadBucket=pulsar-topic-offload

Bucket region​

A bucket region is a region where a bucket is located. If a bucket region is not specified, the default region (US East (N. Virginia)) is used.

tip

For more information about AWS regions and endpoints, see here.

Example​

This example sets the bucket region as europe-west-3.


s3ManagedLedgerOffloadRegion=eu-west-3

Authentication (required)​

To be able to access AWS S3, you need to authenticate with AWS S3.

Pulsar does not provide any direct methods of configuring authentication for AWS S3, but relies on the mechanisms supported by the DefaultAWSCredentialsProviderChain.

Once you have created a set of credentials in the AWS IAM console, you can configure credentials using one of the following methods.

  • Use EC2 instance metadata credentials.

    If you are on AWS instance with an instance profile that provides credentials, Pulsar uses these credentials if no other mechanism is provided.

  • Set the environment variables AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY in conf/pulsar_env.sh.

    "export" is important so that the variables are made available in the environment of spawned processes.


    export AWS_ACCESS_KEY_ID=ABC123456789
    export AWS_SECRET_ACCESS_KEY=ded7db27a4558e2ea8bbf0bf37ae0e8521618f366c

  • Add the Java system properties aws.accessKeyId and aws.secretKey to PULSAR_EXTRA_OPTS in conf/pulsar_env.sh.


    PULSAR_EXTRA_OPTS="${PULSAR_EXTRA_OPTS} ${PULSAR_MEM} ${PULSAR_GC} -Daws.accessKeyId=ABC123456789 -Daws.secretKey=ded7db27a4558e2ea8bbf0bf37ae0e8521618f366c -Dio.netty.leakDetectionLevel=disabled -Dio.netty.recycler.maxCapacityPerThread=4096"

  • Set the access credentials in ~/.aws/credentials.


    [default]
    aws_access_key_id=ABC123456789
    aws_secret_access_key=ded7db27a4558e2ea8bbf0bf37ae0e8521618f366c

  • Assume an IAM role.

    This example uses the DefaultAWSCredentialsProviderChain for assuming this role.

    The broker must be rebooted for credentials specified in pulsar_env to take effect.


    s3ManagedLedgerOffloadRole=<aws role arn>
    s3ManagedLedgerOffloadRoleSessionName=pulsar-s3-offload

Size of block read/write​

You can configure the size of a request sent to or read from AWS S3 in the configuration file broker.conf or standalone.conf.

ConfigurationDescriptionDefault value
s3ManagedLedgerOffloadReadBufferSizeInBytesBlock size for each individual read when reading back data from AWS S3.1 MB
s3ManagedLedgerOffloadMaxBlockSizeInBytesMaximum size of a "part" sent during a multipart upload to AWS S3. It cannot be smaller than 5 MB.64 MB

Configure AWS S3 offloader to run automatically​

Namespace policy can be configured to offload data automatically once a threshold is reached. The threshold is based on the size of data that a topic has stored on a Pulsar cluster. Once the topic reaches the threshold, an offloading operation is triggered automatically.

Threshold valueAction

0 | It triggers the offloading operation if the topic storage reaches its threshold. = 0|It causes a broker to offload data as soon as possible. < 0 |It disables automatic offloading operation.

Automatic offloading runs when a new segment is added to a topic log. If you set the threshold on a namespace, but few messages are being produced to the topic, offloader does not work until the current segment is full.

You can configure the threshold size using CLI tools, such as pulsar-admin.

The offload configurations in broker.conf and standalone.conf are used for the namespaces that do not have namespace level offload policies. Each namespace can have its own offload policy. If you want to set offload policy for each namespace, use the command pulsar-admin namespaces set-offload-policies options command.

Example​

This example sets the AWS S3 offloader threshold size to 10 MB using pulsar-admin.


bin/pulsar-admin namespaces set-offload-threshold --size 10M my-tenant/my-namespace

tip

For more information about the pulsar-admin namespaces set-offload-threshold options command, including flags, descriptions, and default values, see here.

Configure AWS S3 offloader to run manually​

For individual topics, you can trigger AWS S3 offloader manually using one of the following methods:

  • Use REST endpoint.

  • Use CLI tools (such as pulsar-admin).

    To trigger it via CLI tools, you need to specify the maximum amount of data (threshold) that should be retained on a Pulsar cluster for a topic. If the size of the topic data on the Pulsar cluster exceeds this threshold, segments from the topic are moved to AWS S3 until the threshold is no longer exceeded. Older segments are moved first.

Example​

  • This example triggers the AWS S3 offloader to run manually using pulsar-admin.


    bin/pulsar-admin topics offload --size-threshold 10M my-tenant/my-namespace/topic1

    Output


    Offload triggered for persistent://my-tenant/my-namespace/topic1 for messages before 2:0:-1

    tip

    For more information about the pulsar-admin topics offload options command, including flags, descriptions, and default values, see here.

  • This example checks the AWS S3 offloader status using pulsar-admin.


    bin/pulsar-admin topics offload-status persistent://my-tenant/my-namespace/topic1

    Output


    Offload is currently running

    To wait for the AWS S3 offloader to complete the job, add the -w flag.


    bin/pulsar-admin topics offload-status -w persistent://my-tenant/my-namespace/topic1

    Output


    Offload was a success

    If there is an error in offloading, the error is propagated to the pulsar-admin topics offload-status command.


    bin/pulsar-admin topics offload-status persistent://my-tenant/my-namespace/topic1

    Output


    Error in offload
    null

    Reason: Error offloading: org.apache.bookkeeper.mledger.ManagedLedgerException: java.util.concurrent.CompletionException: com.amazonaws.services.s3.model.AmazonS3Exception: Anonymous users cannot initiate multipart uploads.  Please authenticate. (Service: Amazon S3; Status Code: 403; Error Code: AccessDenied; Request ID: 798758DE3F1776DF; S3 Extended Request ID: dhBFz/lZm1oiG/oBEepeNlhrtsDlzoOhocuYMpKihQGXe6EG8puRGOkK6UwqzVrMXTWBxxHcS+g=), S3 Extended Request ID: dhBFz/lZm1oiG/oBEepeNlhrtsDlzoOhocuYMpKihQGXe6EG8puRGOkK6UwqzVrMXTWBxxHcS+g=

    tip

    For more information about the pulsar-admin topics offload-status options command, including flags, descriptions, and default values, see here.

Tutorial​

For the complete and step-by-step instructions on how to use the AWS S3 offloader with Pulsar, see here.

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