Installing the Starlight for Kafka extension

This document will help you get started producing and consuming Kafka messages on a Pulsar cluster.

This guide is focused on installing the extension into an existing Pulsar cluster. There is also the "Getting started with the Starlight for Kafka extension" which provides more options.

Check prerequisites
Download protocol handler
Build protocol handler from source (optional)
Configure protocol handler
Test Starlight for Kafka

Prerequisites

Starlight for Kafka requires the following Pulsar versions and Kafka clients.

Starlight for Kafka Version	Compatible Pulsar version	Supported Kafka client
2.10	2.10.x	0.10, 1.x, 2.x, 3.x
2.8	2.8.x	0.10, 1.x, 2.x, 3.x

Starlight for Kafka Version

Compatible Pulsar version

Supported Kafka client

2.10

2.10.x

0.10, 1.x, 2.x, 3.x

2.8

2.8.x

0.10, 1.x, 2.x, 3.x

Starlight for Kafka supports all major Kafka clients (0.10, 1.x, 2.x, 3.x).

Starlight for Kafka supports Kafka Streams and the Kafka CLI.

Starlight for Kafka requires JDK11.

Download

If this is the first time you’ve used protocol handlers with your Pulsar deployment, create a protocols folder in the root of your Pulsar directory.
Download pulsar-protocol-handler-kafka-2.10.nar here.
Copy the .nar file to your Pulsar/protocols directory.
Proceed to Configure protocol handler.

Build Starlight for Kafka protocol handler from source (optional)

If you prefer, build the protocol handler .nar from source.

Clone the Starlight for Kafka GitHub repo to your local machine and change directory into the repo.
```
git clone https://github.com/datastax/starlight-for-kafka.git
cd starlight-for-kafka
```
Starlight for Kafka requires JDK11. Set jenv global 11 to use JDK 11.

Build the Maven project.

mvn clean install -DskipTests

You will get an output like this:

[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  03:51 min
[INFO] Finished at: 2022-06-24T12:04:14-04:00

If this is the first time you’ve used protocol handlers with your Pulsar deployment, create a protocols folder in the root of your Pulsar directory.
The protocol handler .nar is now available at starlight-for-kafka/kafka-impl/target/pulsar-protocol-handler-kafka-2.10.nar.
Copy the .nar file to your Pulsar protocols directory and proceed to Configure protocol handler

Configure protocol handler

Configure the Pulsar broker to run the Starlight for Kafka protocol handler as a plugin by adding configurations in the Pulsar configuration file broker.conf.

Modify standalone.conf if you’re running Pulsar standalone.

Add these configuration values to broker.conf:

messagingProtocols=kafka
protocolHandlerDirectory=./protocols
allowAutoTopicCreationType=partitioned

Property Default Value Suggested Value

Property	Default Value	Suggested Value
`messagingProtocols`		kafka
`protocolHandlerDirectory`	./protocols	Location of Starlight for Kafka NAR file
`allowAutoTopicCreationType`	non-partitioned	partitioned

messagingProtocols

kafka

protocolHandlerDirectory

./protocols

Location of Starlight for Kafka NAR file

allowAutoTopicCreationType

non-partitioned

partitioned

allowAutoTopicCreationType is set to non-partitioned by default. Since topics are partitioned by default in Kafka, it’s better to avoid creating non-partitioned topics unless Kafka clients need to interact with existing non-partitioned topics.

Set Kafka listeners. kafkaListeners is a comma-separated list of listeners, and the host/IP and port which Kafka binds to for listening.
```
kafkaListeners=PLAINTEXT://127.0.0.1:9092
```
Set Kafka advertised listeners. kafkaAdvertisedListeners is a comma-separated list of listeners with their host/IP and port.
kafkaAdvertisedListeners is not required unless you want to expose another address to the Kafka client. It defaults to the same address as kafkaListeners by default.
```
kafkaAdvertisedListeners=PLAINTEXT://127.0.0.1:9092
```
Set offset management. Offset management is required because Starlight for Kafka depends upon Pulsar broker-level entry metadata.
```
brokerEntryMetadataInterceptors=org.apache.pulsar.common.intercept.AppendIndexMetadataInterceptor
```
Disable the deletion of inactive topics. This is not required but very important in Starlight for Kafka.
By default, Pulsar deletes inactive partitions of a partitioned topic, but the metadata of the partitioned topic is not deleted.
Starlight for Kafka cannot create missed partitions if brokerDeleteInactiveTopicsEnabled is set to true.
```
brokerDeleteInactiveTopicsEnabled=false
```

Additional configurations

Set both retention and time to live policies TTL for Starlight for Kafka namespaces. If you only configure retention without configuring TTL, all messages on Starlight for Kafka topics cannot be deleted because Starlight for Kafka does not update a durable cursor.
If a Pulsar consumer and a Kafka consumer both subscribe to the same topic with the same subscription (or group) name, the two consumers consume messages independently and they do not share the same subscription, even though the subscription name of a Pulsar client is the same with the group name of a Kafka client.
Starlight for Kafka supports interaction between Pulsar client and Kafka client by default. If your topic is used only by the Pulsar client or only by the Kafka client, you can set entryFormat=kafka in broker.conf for better performance.

Test

After you have installed the Starlight for Kafka protocol handler and modified the Pulsar broker configuration, verify your Starlight for Kafka deployment works by running a Kafka client and consuming the messages on Pulsar.

Restart your Pulsar brokers.
Download Kafka 3.0.0 and untar the release package.
```
tar -xzf kafka-3.0.0.tgz
cd kafka-3.0.0
```
Run the Kafka command-line consumer to listen for messages from the server. Here we’re using localhost and Pulsar standalone.
```
bin/kafka-console-consumer.sh --bootstrap-server PLAINTEXT://127.0.0.1:9092 --topic test --from-beginning
```
Create a consumer on Pulsar to consume messages. Here we’re adding -n 0 to tell Pulsar to continue running instead of closing the connection after consuming a message.
```
pulsar-client consume test -s "my-subscription" -n 0
```

Run the Kafka command-line producer to send messages to the server, and send a message.

bin/kafka-console-producer.sh --bootstrap-server PLAINTEXT://127.0.0.1:9092 --topic test
>hi pulsar, it's me, kafka!

If Starlight for Kafka is working, your message will appear on your Pulsar consumer.

----- got message -----
key:[null], properties:[], content:hi pulsar, it's me, kafka!

What’s next?

You can configure and manage Starlight for Kafka based on your requirements. Check the following guides for more details.