Connect to your cluster using the Kafka Go client

This document describes how to connect to your Pulsar cluster using the Kafka Go client through Token authentication.

Before you begin

• Get the JWT token.

  1. On the left navigation pane, click Service Accounts.

  2. In the row of the service account you want to use, in the Token column, click Generate new token, then click the Copy icon to copy the token to your clipboard.

• Get the service URL of your Pulsar cluster.

  1. On the left navigation pane, in the Admin area, click Pulsar Clusters.
  2. Select the Overview tab, and in the Access Points area, click Copy at the end of the row of the Kafka Service URL (TCP).

Steps

1. Install the Kafka Go client.

   go get -u github.com/confluentinc/confluent-kafka-go/v2/kafka
   

2. Build a Go application to produce and consume messages.

   package main
   
   import (
     "fmt"
     "github.com/confluentinc/confluent-kafka-go/v2/kafka"
     "time"
   )
   
   func main() {
     // Step 1: replace with your configurations
     serverUrl := "SERVER-URL"
     jwtToken := "YOUR-TOKEN"
     topicName := "persistent://public/default/connect-test"
     namespace := "public/default"
     password := "token:" + jwtToken
   
     // Step 2: create a producer to send messages
     producer, err := kafka.NewProducer(&kafka.ConfigMap{
       "bootstrap.servers": serverUrl,
       "security.protocol": "SASL_SSL",
       "sasl.mechanism":    "PLAIN",
       "sasl.username":     namespace,
       "sasl.password":     password,
     })
     if err != nil {
       panic(err)
     }
     defer producer.Close()
   
     err = producer.Produce(&kafka.Message{
       TopicPartition: kafka.TopicPartition{Topic: &topicName, Partition: kafka.PartitionAny},
       Value:          []byte("hello world"),
     }, nil)
   
     if err != nil {
       panic(err)
     }
     producer.Flush(1000)
   
     // wait for delivery report
     e := <-producer.Events()
   
     message := e.(*kafka.Message)
     if message.TopicPartition.Error != nil {
       fmt.Printf("failed to deliver message: %v\n",
         message.TopicPartition)
     } else {
       fmt.Printf("delivered to topic %s [%d] at offset %v\n",
         *message.TopicPartition.Topic,
         message.TopicPartition.Partition,
         message.TopicPartition.Offset)
     }
   
     // Step 3: create a consumer to read messages
     consumer, err := kafka.NewConsumer(&kafka.ConfigMap{
       "bootstrap.servers":  serverUrl,
       "security.protocol":  "SASL_SSL",
       "sasl.mechanisms":    "PLAIN",
       "sasl.username":      namespace,
       "sasl.password":      password,
       "session.timeout.ms": 6000,
       "group.id":           "my-group",
       "auto.offset.reset":  "earliest",
     })
   
     if err != nil {
       panic(fmt.Sprintf("Failed to create consumer: %s", err))
     }
     defer consumer.Close()
   
     topics := []string{topicName}
     err = consumer.SubscribeTopics(topics, nil)
     if err != nil {
       panic(fmt.Sprintf("Failed to subscribe topics: %s", err))
     }
   
     // read one message then exit
     for {
       fmt.Println("polling...")
       message, err = consumer.ReadMessage(1 * time.Second)
       if err == nil {
         fmt.Printf("consumed from topic %s [%d] at offset %v: %+v",
           *message.TopicPartition.Topic,
           message.TopicPartition.Partition, message.TopicPartition.Offset, string(message.Value))
         break
       }
     }
   }
   

   • serverUrl: the Kafka service URL of your Pulsar cluster.
   • jwtToken: the token of your service account.

3. Run the Go application and you should see the following output:

   delivered to topic persistent://public/default/connect-test [0] at offset 29
   polling...
   polling...
   polling...
   polling...
   polling...
   polling...
   polling...
   consumed from topic persistent://public/default/connect-test [0] at offset 15: hello world