Go

This section describes how to access a Kafka instance using Go 1.16.5 on the Linux CentOS, how to obtain the demo code, and how to produce and consume messages.

Before getting started, ensure that you have collected the information listed in Collecting Connection Information.

Preparing the Environment

Run the following command to check whether Go has been installed:
```
go version
```
If the following information is displayed, Go has been installed.
```
[root@ecs-test confluent-kafka-go]# go version
go version go1.16.5 linux/amd64
```
If Go is not installed, download and install it.
Run the following command to obtain the code used in the demo:
```
go get github.com/confluentinc/confluent-kafka-go/kafka
```

Producing Messages

Replace the following information in bold with the actual values.

With SASL

package main

import (
	"bufio"
	"fmt"
	"github.com/confluentinc/confluent-kafka-go/kafka"
	"log"
	"os"
	"os/signal"
	"syscall"
)

var (
    brokers  = "ip1:port1,ip2:port2,ip3:port3"
	topics   = "topic_name"
	user     = "username"
	password = "password"
	caFile   = "phy_ca.crt"     //Certificate file. For details about how to obtain an SSL certificate, see section "Collecting Connection Information."
)

func main() {
	log.Println("Starting a new kafka producer")

	config := &kafka.ConfigMap{
		"bootstrap.servers": brokers,
		"security.protocol": "SASL_SSL",
		"sasl.mechanism":    "PLAIN",
		"sasl.username":     user,
		"sasl.password":     password,
		"ssl.ca.location":   caFile,                
		"ssl.endpoint.identification.algorithm": "none"
	}
	producer, err := kafka.NewProducer(config)
	if err != nil {
		log.Panicf("producer error, err: %v", err)
		return
	}

	go func() {
		for e := range producer.Events() {
			switch ev := e.(type) {
			case *kafka.Message:
				if ev.TopicPartition.Error != nil {
					log.Printf("Delivery failed: %v\n", ev.TopicPartition)
				} else {
					log.Printf("Delivered message to %v\n", ev.TopicPartition)
				}
			}
		}
	}()

	// Produce messages to topic (asynchronously)
	fmt.Println("please enter message:")
	go func() {
		for {
			err := producer.Produce(&kafka.Message{
				TopicPartition: kafka.TopicPartition{Topic: &topics, Partition: kafka.PartitionAny},
				Value:          GetInput(),
			}, nil)
			if err != nil {
				log.Panicf("send message fail, err: %v", err)
				return
			}
		}
	}()

	sigterm := make(chan os.Signal, 1)
	signal.Notify(sigterm, syscall.SIGINT, syscall.SIGTERM)
	select {
	case <-sigterm:
		log.Println("terminating: via signal")
	}
	// Wait for message deliveries before shutting down
	producer.Flush(15 * 1000)
	producer.Close()
}

func GetInput() []byte {
	reader := bufio.NewReader(os.Stdin)
	data, _, _ := reader.ReadLine()
	return data
}

The parameters in the example code are described as follows. For details about how to obtain the parameter values, see Collecting Connection Information.

brokers: instance connection address and port
topics: topic name
user and password: username and password you set when enabling SASL_SSL during Kafka instance creation or when creating a SASL_SSL user.
caFile: certificate file
security.protocol: Kafka security protocol. View it on the Basic Information page of the Kafka instance console. If Security Protocol is not displayed, SASL_SSL is used by default.
sasl.mechanism: SASL authentication mechanism. View it on the Basic Information page of the Kafka instance console. If both SCRAM-SHA-512 and PLAIN are enabled, configure either of them for connections. If SASL Mechanism is not displayed, PLAIN is used by default.

Without SASL

package main

import (
	"bufio"
	"fmt"
	"github.com/confluentinc/confluent-kafka-go/kafka"
	"log"
	"os"
	"os/signal"
	"syscall"
)

var (
	brokers  = "ip1:port1,ip2:port2,ip3:port3"
	topics   = "topic_name"
)

func main() {
	log.Println("Starting a new kafka producer")

	config := &kafka.ConfigMap{
		"bootstrap.servers": brokers,
	}
	producer, err := kafka.NewProducer(config)
	if err != nil {
		log.Panicf("producer error, err: %v", err)
		return
	}

	go func() {
		for e := range producer.Events() {
			switch ev := e.(type) {
			case *kafka.Message:
				if ev.TopicPartition.Error != nil {
					log.Printf("Delivery failed: %v\n", ev.TopicPartition)
				} else {
					log.Printf("Delivered message to %v\n", ev.TopicPartition)
				}
			}
		}
	}()

	// Produce messages to topic (asynchronously)
	fmt.Println("please enter message:")
	go func() {
		for {
			err := producer.Produce(&kafka.Message{
				TopicPartition: kafka.TopicPartition{Topic: &topics, Partition: kafka.PartitionAny},
				Value:          GetInput(),
			}, nil)
			if err != nil {
				log.Panicf("send message fail, err: %v", err)
				return
			}
		}
	}()

	sigterm := make(chan os.Signal, 1)
	signal.Notify(sigterm, syscall.SIGINT, syscall.SIGTERM)
	select {
	case <-sigterm:
		log.Println("terminating: via signal")
	}
	// Wait for message deliveries before shutting down
	producer.Flush(15 * 1000)
	producer.Close()
}

func GetInput() []byte {
	reader := bufio.NewReader(os.Stdin)
	data, _, _ := reader.ReadLine()
	return data
}

The parameters in the example code are described as follows. For details about how to obtain the parameter values, see Collecting Connection Information.

brokers: instance connection address and port
topics: topic name

Consuming Messages

Replace the following information in bold with the actual values.

With SASL

package main

import (
	"fmt"
	"github.com/confluentinc/confluent-kafka-go/kafka"
	"log"
	"os"
	"os/signal"
	"syscall"
)

var (
	brokers  = "ip1:port1,ip2:port2,ip3:port3"
	group    = "group-id"
	topics   = "topic_name"
	user     = "username"
	password = "password"
	caFile   = "phy_ca.crt"     //Certificate file. For details about how to obtain an SSL certificate, see section "Collecting Connection Information."
)

func main() {
	log.Println("Starting a new kafka consumer")

	config := &kafka.ConfigMap{
		"bootstrap.servers": brokers,
		"group.id":          group,
		"auto.offset.reset": "earliest",
		"security.protocol": "SASL_SSL",
		"sasl.mechanism":    "PLAIN",
		"sasl.username":     user,
		"sasl.password":     password,
		"ssl.ca.location":   caFile,                
		"ssl.endpoint.identification.algorithm": "none"
	}

	consumer, err := kafka.NewConsumer(config)
	if err != nil {
		log.Panicf("Error creating consumer: %v", err)
		return
	}

	err = consumer.SubscribeTopics([]string{topics}, nil)
	if err != nil {
		log.Panicf("Error subscribe consumer: %v", err)
		return
	}

	go func() {
		for {
			msg, err := consumer.ReadMessage(-1)
			if err != nil {
				log.Printf("Consumer error: %v (%v)", err, msg)
			} else {
				fmt.Printf("Message on %s: %s\n", msg.TopicPartition, string(msg.Value))
			}
		}
	}()

	sigterm := make(chan os.Signal, 1)
	signal.Notify(sigterm, syscall.SIGINT, syscall.SIGTERM)
	select {
	case <-sigterm:
		log.Println("terminating: via signal")
	}
	if err = consumer.Close(); err != nil {
		log.Panicf("Error closing consumer: %v", err)
	}
}

The parameters in the example code are described as follows. For details about how to obtain the parameter values, see Collecting Connection Information.

brokers: instance connection address and port
group: custom consumer group name. If the specified consumer group does not exist, Kafka automatically creates one.
topics: topic name
user and password: username and password you set when enabling SASL_SSL during Kafka instance creation or when creating a SASL_SSL user.
caFile: certificate file
security.protocol: Kafka security protocol. View it on the Basic Information page of the Kafka instance console. If Security Protocol is not displayed, SASL_SSL is used by default.
sasl.mechanism: SASL authentication mechanism. View it on the Basic Information page of the Kafka instance console. If both SCRAM-SHA-512 and PLAIN are enabled, configure either of them for connections. If SASL Mechanism is not displayed, PLAIN is used by default.

Without SASL

package main

import (
	"fmt"
	"github.com/confluentinc/confluent-kafka-go/kafka"
	"log"
	"os"
	"os/signal"
	"syscall"
)

var (
	brokers  = "ip1:port1,ip2:port2,ip3:port3"
	group    = "group-id"
	topics   = "topic_name"
)

func main() {
	log.Println("Starting a new kafka consumer")

	config := &kafka.ConfigMap{
		"bootstrap.servers": brokers,
		"group.id":          group,
		"auto.offset.reset": "earliest",
	}

	consumer, err := kafka.NewConsumer(config)
	if err != nil {
		log.Panicf("Error creating consumer: %v", err)
		return
	}

	err = consumer.SubscribeTopics([]string{topics}, nil)
	if err != nil {
		log.Panicf("Error subscribe consumer: %v", err)
		return
	}

	go func() {
		for {
			msg, err := consumer.ReadMessage(-1)
			if err != nil {
				log.Printf("Consumer error: %v (%v)", err, msg)
			} else {
				fmt.Printf("Message on %s: %s\n", msg.TopicPartition, string(msg.Value))
			}
		}
	}()

	sigterm := make(chan os.Signal, 1)
	signal.Notify(sigterm, syscall.SIGINT, syscall.SIGTERM)
	select {
	case <-sigterm:
		log.Println("terminating: via signal")
	}
	if err = consumer.Close(); err != nil {
		log.Panicf("Error closing consumer: %v", err)
	}
}

The parameters in the example code are described as follows. For details about how to obtain the parameter values, see Collecting Connection Information.

brokers: instance connection address and port
group: custom consumer group name. If the specified consumer group does not exist, Kafka automatically creates one.
topics: topic name

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