JGroups AWS – S3_PING

Table of Contents

• Maven Coordinates
• Protocol Configuration
  • Possible Configurations
  • Example Stack
• Testing
• Reporting Issues
• Support Matrix

Projects JGroups AWS provides an implementation of S3_PING discovery protocol using AWS S3 buckets as cluster information store. It is based on the original code written by Tobias Sarnowski at Zalando. ^{[1] [2]}

It uses the official AWS SDK ^[3] and does not implement the HTTP protocol on its own. The benefit is a more stable connection as well as usage of IAM server profiles and AWS standardized credential distribution.

Maven Coordinates

<dependency>
    <groupId>org.jgroups.aws</groupId>
    <artifactId>jgroups-aws</artifactId>
    <version>3.0.0.Final</version>
</dependency>

Protocol Configuration

This library implements a JGroups discovery protocol which replaces protocols like MPING or TCPPING.

<aws.S3_PING region_name="us-east-1a"
             bucket_name="jgroups-s3-test"/>

The aws.S3_PING automatically registers itself to JGroups with the magic number 789. You can overwrite this by setting the system property s3ping.magic_number to different number, e.g. -Ds3ping.magic_number=123.

Possible Configurations

• region_name: like "eu-west-1", "us-east-1", etc.

• bucket_name: the S3 bucket to store the files in

• bucket_prefix (optional): if you don’t want the plugin to pollute your S3 bucket, you can configure a prefix like "jgroups/"

• endpoint (optional): you can override the S3 endpoint if you know what you are doing

• kms_key_id (optional): you can set this to a kms key id to enable KMS-SSE encryption when writing data to S3 (see https://docs.aws.amazon.com/AmazonS3/latest/userguide/UsingKMSEncryption.html)

Example Stack

<!--
Based on tcp.xml but with new aws.S3_PING.
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns="urn:org:jgroups"
        xsi:schemaLocation="urn:org:jgroups http://www.jgroups.org/schema/jgroups.xsd">
    <TCP bind_port="7800"
         recv_buf_size="${tcp.recv_buf_size:5M}"
         send_buf_size="${tcp.send_buf_size:5M}"
         max_bundle_size="64K"
         thread_pool.enabled="true"
         thread_pool.min_threads="2"
         thread_pool.max_threads="8"
         thread_pool.keep_alive_time="5000"/>

    <aws.S3_PING region_name="eu-west-1"
                 bucket_name="jgroups-s3-test"
                 bucket_prefix="jgroups"/>

    <MERGE3 min_interval="10000"
            max_interval="30000"/>

    <FD_SOCK/>
    <FD_ALL timeout="30000" interval="5000"/>
    <VERIFY_SUSPECT timeout="1500"/>
    <pbcast.NAKACK2 use_mcast_xmit="false"
                    discard_delivered_msgs="true"/>

    <UNICAST3/>

    <pbcast.STABLE stability_delay="1000" desired_avg_gossip="50000"
                   max_bytes="4M"/>
    <pbcast.GMS print_local_addr="true" join_timeout="2000"
                view_bundling="true"/>
    <MFC max_credits="2M"
         min_threshold="0.4"/>
    <FRAG2 frag_size="60K"/>
</config>

Testing

Running the automated tests requires having AWS credentials setup with appropriate permissions along with setting the region name and a bucket name.

declare -x AWS_ACCESS_KEY_ID="qF7ujVAaYUp3Tx7m"
declare -x AWS_SECRET_ACCESS_KEY="WzbG3R2KGtx5rsHQUx2PKQPS2f6WzMtf"
declare -x S3_PING_REGION_NAME="eu-central-1"
declare -x S3_PING_BUCKET_NAME="jgroups"
mvn verify

If any of the required properties are not specified tests will be skipped (uses org.junit.Assume).

In case credentials are not provided and running on Linux, tests will be run against mock containerized S3 instance. These require a functioning podman or Docker environment.

Reporting Issues

Project JGroups AWS uses GitHub Issues for tracking:

https://github.com/jgroups-extras/jgroups-aws/issues

Support Matrix

Version (branch)	JGroups version	AWS SDK
main	5.2.x - 5.3.x	2.x
2.x	5.2.x	1.x
1.x	4.2.x	1.x

---

1. https://libraries.io/github/zalando/jgroups-native-s3-ping

2. https://github.com/jwegne/jgroups-native-s3-ping

3. http://docs.aws.amazon.com/AmazonS3/latest/dev/UsingTheMPDotJavaAPI.html