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Use Aliyun OSS offloader with Pulsar

This chapter guides you through every step of installing and configuring the Aliyun Object Storage Service (OSS) offloader and using it with Pulsar.

Installation​

Follow the steps below to install the Aliyun OSS offloader.

Prerequisite​

  • Pulsar: 2.8.0 or later versions

Steps​

  1. Download the Pulsar tarball.
  2. Download and untar the Pulsar offloaders package, then copy the Pulsar offloaders as offloaders in the Pulsar directory. See Install tiered storage offloaders.

Configuration​

note

Before offloading data from BookKeeper to Aliyun OSS, you need to configure some properties of the Aliyun OSS offload driver. Besides, you can also configure the Aliyun OSS offloader to run it automatically or trigger it manually.

Configure Aliyun OSS offloader driver​

You can configure the Aliyun OSS 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.aliyun-oss
    offloadersDirectoryOffloader directoryoffloaders
    managedLedgerOffloadBucketBucketpulsar-topic-offload
    managedLedgerOffloadServiceEndpointEndpointhttp://oss-cn-hongkong.aliyuncs.com
  • Optional configurations are as below.

    OptionalDescriptionDefault value
    managedLedgerOffloadReadBufferSizeInBytesBlock size for each individual read when reading back data from S3-compatible storage.1 MB
    managedLedgerOffloadMaxBlockSizeInBytesMaximum block size sent during a multi-part upload to S3-compatible storage. It cannot be smaller than 5 MB.64 MB
    managedLedgerMinLedgerRolloverTimeMinutesMinimum time between ledger rollover for a topic.

    It's not recommended to change the default value in a production environment.
    2
    managedLedgerMaxEntriesPerLedgerMaximum number of entries to append to a ledger before triggering a rollover.

    Note: It's not recommended to change the default value in a production environment.
    5000

Bucket (required)​

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

Example​

This example names the bucket pulsar-topic-offload.

managedLedgerOffloadBucket=pulsar-topic-offload

Endpoint (required)​

The endpoint is the region where a bucket is located.

tip

For more information about Aliyun OSS regions and endpoints, see International website or Chinese website.

Example​

This example sets the endpoint as oss-us-west-1-internal.

managedLedgerOffloadServiceEndpoint=http://oss-us-west-1-internal.aliyuncs.com

Authentication (required)​

To be able to access Aliyun OSS, you need to authenticate with Aliyun OSS.

Set the environment variables ALIYUN_OSS_ACCESS_KEY_ID and ALIYUN_OSS_ACCESS_KEY_SECRET in conf/pulsar_env.sh.

export ALIYUN_OSS_ACCESS_KEY_ID=ABC123456789
export ALIYUN_OSS_ACCESS_KEY_SECRET=ded7db27a4558e2ea8bbf0bf37ae0e8521618f366c
note

Exporting these environment variables makes them available in the environment of spawned processes.

Run Aliyun OSS offloader 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 in a Pulsar cluster. Once the topic reaches the threshold, an offloading operation is triggered automatically.

Threshold valueAction
> 0It triggers the offloading operation if the topic storage reaches its threshold.
= 0It causes a broker to offload data as soon as possible.
< 0It 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, the 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 offload policy. If you want to set an offload policy for a specific namespace, use the command pulsar-admin namespaces set-offload-policies options command.

Example​

This example sets the Aliyun OSS 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 Pulsar admin docs.

Run Aliyun OSS offloader manually​

For individual topics, you can trigger the Aliyun OSS 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 in 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 Aliyun OSS until the threshold is no longer exceeded. Older segments are moved first.

Example​

  • This example triggers the Aliyun OSS 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 Pulsar admin docs.

  • This example checks the Aliyun OSS 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 Aliyun OSS 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 Pulsar admin docs.