sarama介绍
截止当前时间,github上golang操作kafka的包主要有两个:
Shopify/sarama starts
confluentinc/confluent-kafka-go starts
saram 使用纯go语言编写, confluent-kafka-go 这是包装了c的api
sarama
Go语言中连接kafka使用第三方库:github.com/Shopify/sarama。
下载及安装
go get github.com/Shopify/sarama
注意事项
sarama v1.20之后的版本加入了zstd压缩算法,需要用到cgo,在Windows平台编译时会提示类似如下错误:
github.com/DataDog/zstd
exec: "gcc":executable file not found in %PATH%
所以在Windows平台请使用v1.19版本的sarama。
kafka发送消息和接收消息
package main
import (
"fmt"
"github.com/Shopify/sarama"
)
// 基于sarama第三方库开发的kafka client
func main() {
config := sarama.NewConfig()
config.Producer.RequiredAcks = sarama.WaitForAll // 发送完数据需要leader和follow都确认
config.Producer.Partitioner = sarama.NewRandomPartitioner // 新选出一个partition
config.Producer.Return.Successes = true // 成功交付的消息将在success channel返回
// 构造一个消息
msg := &sarama.ProducerMessage{
}
msg.Topic = "web_log"
msg.Value = sarama.StringEncoder("this is a test log")
// 连接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()
// 发送消息
pid, offset, err := client.SendMessage(msg)
if err != nil {
fmt.Println("send msg failed, err:", err)
return
}
fmt.Printf("pid:%v offset:%v\n", pid, offset)
}
消费者
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:%v\n", err)
return
}
partitionList, err := consumer.Partitions("web_log") // 根据topic取到所有的分区
if err != nil {
fmt.Printf("fail to get list of partition:err%v\n", err)
return
}
fmt.Println(partitionList)
for partition := range partitionList {
// 遍历所有的分区
// 针对每个分区创建一个对应的分区消费者
pc, err := consumer.ConsumePartition("web_log", int32(partition), sarama.OffsetNewest)
if err != nil {
fmt.Printf("failed to start consumer for partition %d,err:%v\n", partition, err)
return
}
defer pc.AsyncClose()
// 异步从每个分区消费信息
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)
}
}
配置文件读取
在,我们编辑 my.ini 文件并输入以下内容(部分内容来自 Grafana)。
# possible values : production, development
app_mode = development
[paths]
# Path to where grafana can store temp files, sessions, and the sqlite3 db (if that is used)
data = /home/git/grafana
[server]
# Protocol (http or https)
protocol = http
# The http port to use
http_port = 9999
# Redirect to correct domain if host header does not match domain
# Prevents DNS rebinding attacks
enforce_domain = true
很好,接下来我们需要编写 main.go 文件来操作刚才创建的配置文件。
package main
import (
"fmt"
"os"
"gopkg.in/ini.v1"
)
func main() {
cfg, err := ini.Load("my.ini")
if err != nil {
fmt.Printf("Fail to read file: %v", err)
os.Exit(1)
}
// 典型读取操作,默认分区可以使用空字符串表示
fmt.Println("App Mode:", cfg.Section("").Key("app_mode").String())
fmt.Println("Data Path:", cfg.Section("paths").Key("data").String())
// 我们可以做一些候选值限制的操作
fmt.Println("Server Protocol:",
cfg.Section("server").Key("protocol").In("http", []string{
"http", "https"}))
// 如果读取的值不在候选列表内,则会回退使用提供的默认值
fmt.Println("Email Protocol:",
cfg.Section("server").Key("protocol").In("smtp", []string{
"imap", "smtp"}))
// 试一试自动类型转换
fmt.Printf("Port Number: (%[1]T) %[1]d\n", cfg.Section("server").Key("http_port").MustInt(9999))
fmt.Printf("Enforce Domain: (%[1]T) %[1]v\n", cfg.Section("server").Key("enforce_domain").MustBool(false))
// 差不多了,修改某个值然后进行保存
cfg.Section("").Key("app_mode").SetValue("production")
cfg.SaveTo("my.ini.local")
}
运行程序,我们可以看下以下输出:
$ go run main.go
App Mode: development
Data Path: /home/git/grafana
Server Protocol: http
Email Protocol: smtp
Port Number: (int) 9999
Enforce Domain: (bool) true
$ cat my.ini.local
# possible values : production, development
app_mode = production
[paths]
# Path to where grafana can store temp files, sessions, and the sqlite3 db (if that is used)
data = /home/git/grafana
...