Go操作Kafka和Etcd方法詳解

2022-09-02 18:02:34

操作Kafka

Kafka 是一種高吞吐量的分散式釋出訂閱訊息系統，它可以處理消費者規模的網站中的所有動作流資料，具有高效能、持久化、多副本備份、橫向擴充套件等特點。本文介紹瞭如何使用 Go 語言傳送和接收 kafka 訊息。

sarama

Go 語言中連線 kafka 使用第三方庫:github.com/Shopify/sar…。

下載及安裝

go get github.com/Shopify/sarama

注意事項

sarama v1.20 之後的版本加入了zstd壓縮演演算法，需要用到 cgo，在 Windows 平臺編譯時會提示類似如下錯誤：

# github.com/DataDog/zstd
exec: "gcc":executable file not found in %PATH%

所以在 Windows 平臺請使用 v1.19 版本的 sarama。

連線 kafka 傳送訊息

package main
import (
	"fmt"
	"github.com/Shopify/sarama"
)
// 基於sarama第三方庫開發的kafka client
func main() {
	config := sarama.NewConfig()
	config.Producer.RequiredAcks = sarama.WaitForAll          // 傳送完資料需要leader和follow都確認
	config.Producer.Partitioner = sarama.NewRandomPartitioner // 新選出一個partition
	config.Producer.Return.Successes = true                   // 成功交付的訊息將在success channel返回
	// 構造一個訊息
	msg := &amp;sarama.ProducerMessage{}
	msg.Topic = "web_log"
	msg.Value = sarama.StringEncoder("this is a test log")
	// 連線kafka
	client, err := sarama.NewSyncProducer([]string{"192.168.1.7:9092"}, config)
	if err != nil {
		fmt.Println("producer closed, err:", err)
		return
	}
	defer client.Close()
	// 傳送訊息
	pid, offset, err := client.SendMessage(msg)
	if err != nil {
		fmt.Println("send msg failed, err:", err)
		return
	}
	fmt.Printf("pid:%v offset:%vn", pid, offset)
}

連線 kafka 消費訊息

package main
import (
	"fmt"
	"github.com/Shopify/sarama"
)
// kafka consumer
func main() {
	consumer, err := sarama.NewConsumer([]string{"127.0.0.1:9092"}, nil)
	if err != nil {
		fmt.Printf("fail to start consumer, err:%vn", err)
		return
	}
	partitionList, err := consumer.Partitions("web_log") // 根據topic取到所有的分割區
	if err != nil {
		fmt.Printf("fail to get list of partition:err%vn", err)
		return
	}
	fmt.Println(partitionList)
	for partition := range partitionList { // 遍歷所有的分割區
		// 針對每個分割區建立一個對應的分割區消費者
		pc, err := consumer.ConsumePartition("web_log", int32(partition), sarama.OffsetNewest)
		if err != nil {
			fmt.Printf("failed to start consumer for partition %d,err:%vn", partition, err)
			return
		}
		defer pc.AsyncClose()
		// 非同步從每個分割區消費資訊
		go func(sarama.PartitionConsumer) {
			for msg := range pc.Messages() {
				fmt.Printf("Partition:%d Offset:%d Key:%v Value:%v", msg.Partition, msg.Offset, msg.Key, msg.Value)
			}
		}(pc)
	}
}

操作Etcd

這裡使用官方的etcd/clientv3包來連線etcd並進行相關操作。

安裝

go get go.etcd.io/etcd/clientv3

put和get操作

put命令用來設定鍵值對資料，get命令用來根據key獲取值。

package main
import (
	"context"
	"fmt"
	"time"
	"go.etcd.io/etcd/clientv3"
)
func main(){
	cli, err := clientv3.New(clientv3.Config{
		Endpoints:   []string{"122.51.79.172:2379"},
		DialTimeout: 5 * time.Second,
	})
	if err != nil {
		// handle error!
		fmt.Printf("connect to etcd failed, err:%vn", err)
		return
	}
	fmt.Println("connect to etcd success")
	defer cli.Close()
	// put
	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
	_, err = cli.Put(ctx, "coolops", "test")
	cancel()
	if err != nil {
		fmt.Printf("put to etcd failed, err:%vn", err)
		return
	}
	// get
	ctx, cancel = context.WithTimeout(context.Background(), time.Second)
	resp, err := cli.Get(ctx, "coolops")
	cancel()
	if err != nil {
		fmt.Printf("get from etcd failed, err:%vn", err)
		return
	}
	for _, ev := range resp.Kvs {
		fmt.Printf("%s:%sn", ev.Key, ev.Value)
	}
}

watch操作

watch用來獲取未來更改的通知。

package main
import (
	"context"
	"fmt"
	"time"
	"go.etcd.io/etcd/clientv3"
)
func main(){
	cli, err := clientv3.New(clientv3.Config{
		Endpoints:   []string{"122.51.79.172:2379"},
		DialTimeout: 5 * time.Second,
	})
	if err != nil {
		// handle error!
		fmt.Printf("connect to etcd failed, err:%vn", err)
		return
	}
	fmt.Println("connect to etcd success")
	defer cli.Close()
	// watch 操作，返回的是一個通道
	rch := cli.Watch(context.Background(), "coolops") // <-chan WatchResponse
	for wresp := range rch {
		for _, ev := range wresp.Events {
			fmt.Printf("Type: %s Key:%s Value:%sn", ev.Type, ev.Kv.Key, ev.Kv.Value)
		}
	}
}

安裝報錯：

go: finding github.com/coreos/pkg latest
# github.com/coreos/etcd/clientv3/balancer/resolver/endpoint
E:DEVGopkgmodgithub.comcoreosetcd@v3.3.19+incompatibleclientv3balancerresolverendpointendpoint.go:114:78: undefined: resolver.BuildOption
E:DEVGopkgmodgithub.comcoreosetcd@v3.3.19+incompatibleclientv3balancerresolverendpointendpoint.go:182:31: undefined: resolver.ResolveNowOption
# github.com/coreos/etcd/clientv3/balancer/picker
E:DEVGopkgmodgithub.comcoreosetcd@v3.3.19+incompatibleclientv3balancerpickererr.go:37:44: undefined: balancer.PickOptions
E:DEVGopkgmodgithub.comcoreosetcd@v3.3.19+incompatibleclientv3balancerpickerroundrobin_balanced.go:55:54: undefined: balancer.PickOptions

解決：將go.mod裡的prpc改為1.26.0版本