etcdetcd

1.安装 

go get go.etcd.io/etcd/client/v3

2.put与get操作 

putget

在代码操作之前，先确保服务器etcd是否已经启动

#查看进程
ps -ef | grep etcd

#如果没有启动，就先启动吧

#不挂断启动
cd /home/randyfield/etcd-release/etcd-v3.2.32-linux-amd64/
nohup ./etcd &

#命令行设置值
export ETCDCTL_API=3
./etcdctl put name "Garfield"

2.1 get值

keyname
package main

import (
 "context"
 "fmt"
 "time"

 clientv3 "go.etcd.io/etcd/client/v3"
)

func main() {
 cli, err := clientv3.New(clientv3.Config{
  Endpoints:   []string{"192.168.31.204:2379"}, //如果是集群，就在后面加所有的节点[]string{"localhost:2379", "localhost:22379", "localhost:32379"},
  DialTimeout: 5 * time.Second,
 })
 if err != nil {
  // handle error!
  fmt.Printf("connect to etcd failed, err:%v\n", err)
  return
 }
 defer cli.Close()

 //context超时控制
 ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
 resp, err := cli.Get(ctx, "name")
 cancel()
 if err != nil {
  fmt.Printf("get from etcd failed,err %v\n", err)
 }
 //遍历键值对
 for _, kv := range resp.Kvs {
  fmt.Printf("%s:%s \n", kv.Key, kv.Value)
 }
}

go build -o etcd-config-center.exe
.\etcd-config-center.exe

小插曲：遇到问题

报错

连接超时了

{"level":"warn","ts":"2021-05-04T14:45:41.425+0800","caller":"v3@v3.5.0-alpha.0/retry_interceptor.go:62","msg":"retrying of unary invoker failed","target":"etcd-endpoints://0xc0000b2380/#initially=[192.168.31.204:2379]","attempt":0,"error":"rpc error: code = DeadlineExceeded desc = context deadline exceeded"}
get from etcd failed,err context deadline exceeded
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xc0000005 code=0x0 addr=0x10 pc=0x9a5781]

goroutine 1 [running]:
main.main()
问题推测

根据错误，盲猜一手端口监听问题

找到原因
etcd
lsof -i:2379
lsof -i:3000
解决问题
localhostnohup
ps -ef | grep etcd
kill -9 1409

etcd
nohup ./etcd --listen-client-urls http://0.0.0.0:2379 --advertise-client-urls http://0.0.0.0:2379 --listen-peer-urls http://0.0.0.0:2380 &

2.2 put值

go build -o etcd-config-center.exe
.\etcd-config-center.exe

putkey-value
//omit above code...
//continue..
//put值
ctx, cancel = context.WithTimeout(context.Background(), time.Second)
_, err = cli.Put(ctx, "address", "成都市高新区")
cancel()
if err != nil {
    fmt.Printf("put to etcd failed, err:%v\n", err)
    return
}

用etcdctl验证一下吧

./etcdctl get address

ETCDCTL_API=3
export ETCDCTL_API=3

putset

3.watch操作 

watch

为了演示效果，继续在上面的代码增加：

// watch key:address change 监控etcd中key的变化-创建、更改、删除
rch := cli.Watch(context.Background(), "address") // <-chan WatchResponse
for wresp := range rch {
    for _, ev := range wresp.Events {
        fmt.Printf("Type: %s Key:%s Value:%s\n", ev.Type, ev.Kv.Key, ev.Kv.Value)
    }
}

运行

go build -o etcd-config-center.exe
.\etcd-config-center.exe

服务器终端执行

./etcdctl put address "成都市高新区应龙南一路"
./etcdctl del address 
./etcdctl put address "四川省巴中市"

etcd

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