Kafka

Kafka is Go client library for Apache Kafka server, released under MIT license.

Kafka provides minimal abstraction over wire protocol, support for transparent failover and easy to use blocking API.

• godoc generated documentation,
• code examples

Example

Write all messages from stdin to kafka and print all messages from kafka topic to stdout.

package main

import (
    "bufio"
    "log"
    "os"
    "strings"

    "github.com/optiopay/kafka/v2"
    "github.com/optiopay/kafka/v2/proto"
)

const (
    topic     = "my-messages"
    partition = 0
)

var kafkaAddrs = []string{"localhost:9092", "localhost:9093"}

// printConsumed read messages from kafka and print them out
func printConsumed(broker kafka.Client) {
    conf := kafka.NewConsumerConf(topic, partition)
    conf.StartOffset = kafka.StartOffsetNewest
    consumer, err := broker.Consumer(conf)
    if err != nil {
        log.Fatalf("cannot create kafka consumer for %s:%d: %s", topic, partition, err)
    }

    for {
        msg, err := consumer.Consume()
        if err != nil {
            if err != kafka.ErrNoData {
                log.Printf("cannot consume %q topic message: %s", topic, err)
            }
            break
        }
        log.Printf("message %d: %s", msg.Offset, msg.Value)
    }
    log.Print("consumer quit")
}

// produceStdin read stdin and send every non empty line as message
func produceStdin(broker kafka.Client) {
    producer := broker.Producer(kafka.NewProducerConf())
    input := bufio.NewReader(os.Stdin)
    for {
        line, err := input.ReadString('\n')
        if err != nil {
            log.Fatalf("input error: %s", err)
        }
        line = strings.TrimSpace(line)
        if line == "" {
            continue
        }

        msg := &proto.Message{Value: []byte(line)}
        if _, err := producer.Produce(topic, partition, msg); err != nil {
            log.Fatalf("cannot produce message to %s:%d: %s", topic, partition, err)
        }
    }
}

func main() {
    conf := kafka.NewBrokerConf("test-client")
    conf.AllowTopicCreation = true

    // connect to kafka cluster
    broker, err := kafka.Dial(kafkaAddrs, conf)
    if err != nil {
        log.Fatalf("cannot connect to kafka cluster: %s", err)
    }
    defer broker.Close()

    go printConsumed(broker)
    produceStdin(broker)
}