github:https://github.com/etcd-io/etcd/tree/master/clientv3

测试go版本

  1. go 1.14
  3. require (
  4.     go.etcd.io/etcd v0.5.0-alpha.5.0.20200910180754-dd1b699fc489
  5.     google.golang.org/genproto v0.0.0-20201210142538-e3217bee35cc // indirect
  6.     google.golang.org/grpc v1.34.0 // indirect
  7. )
  9. replace (
  10.     go.etcd.io/etcd => go.etcd.io/etcd v0.5.0-alpha.5.0.20200910180754-dd1b699fc489 // ae9734ed278b is the SHA for git tag v3.4.13
  11.     google.golang.org/grpc => google.golang.org/grpc v1.27.1
  12. )

或者

  1. go 1.14
  3. replace (
  4.     github.com/coreos/bbolt => go.etcd.io/bbolt v1.3.5
  5.     google.golang.org/grpc => google.golang.org/grpc v1.26.0
  6. )
  8. require (
  9.     github.com/coreos/bbolt v0.0.0-00010101000000-000000000000 // indirect
  10.     github.com/coreos/etcd v3.3.25+incompatible // indirect
  11.     github.com/coreos/pkg v0.0.0-20180928190104-399ea9e2e55f // indirect
  12.     github.com/google/uuid v1.2.0 // indirect
  13.     github.com/prometheus/client_golang v1.9.0 // indirect
  14.     go.etcd.io/etcd v3.3.25+incompatible
  15.     go.uber.org/zap v1.16.0 // indirect
  16.     golang.org/x/crypto v0.0.0-20210220033148-5ea612d1eb83 // indirect
  17.     google.golang.org/grpc v1.35.0 // indirect
  18. )

grpc和etcd

https://github.com/etcd-io/etcd/issues/12124#issuecomment-674368288
图片.png
bblt

  1. github.com/coreos/etcd/clientv3 tested by
  2.         github.com/coreos/etcd/clientv3.test imports
  3.         github.com/coreos/etcd/auth imports
  4.         github.com/coreos/etcd/mvcc/backend imports
  5.         github.com/coreos/bbolt: github.com/coreos/bbolt@v1.3.5: parsing go.mod:
  6.         module declares its path as: go.etcd.io/bbolt
  7.                 but was required as: github.com/coreos/bbolt

解决

  1. replace github.com/coreos/bbolt => go.etcd.io/bbolt v1.3.5

helloword

  1. package main
  3. import (
  4.     "context"
  5.     "log"
  6.     "time"
  8.     "go.etcd.io/etcd/clientv3"
  9. )
  11. func main() {
  13.     client, err := clientv3.New(clientv3.Config{
  14.         Endpoints:   []string{"127.0.0.1:2379"}, // 集群列表
  15.         DialTimeout: 5 * time.Second,
  16.     })
  17.     if err != nil {
  18.         log.Fatal(err)
  19.     }
  20.     kv := clientv3.NewKV(client)
  21.     res, err := kv.Put(context.TODO(), "/config/dev/hello", "world", clientv3.WithPrevKV())
  22.     if err != nil {
  23.         log.Fatal(err)
  24.     }
  25.     log.Println("Revision:", res.Header.Revision)
  26.     if res.PrevKv != nil {
  27.         log.Println("PrevValue:", string(res.PrevKv.Value))
  28.     }
  29. }

基本操作

put命令用来设置键值对数据，
get命令用来根据key获取值。
delete命令删除key

  1. package main
  3. import (
  4.     "context"
  5.     "fmt"
  6.     "time"
  8.     "go.etcd.io/etcd/clientv3"
  9. )
  11. func main() {
  12.     cli, err := clientv3.New(clientv3.Config{
  13.         Endpoints:   []string{"127.0.0.1:2379"},
  14.         DialTimeout: 2 * time.Second,
  15.     })
  16.     if err != nil {
  17.         fmt.Printf("connect etcd failed,%v\n", err)
  18.         return
  19.     }
  20.     defer cli.Close()
  21.     _, err = cli.Put(context.TODO(), "hello", "etcd")
  22.     if err != nil {
  23.         fmt.Printf("put etcd failed, %v\n", err)
  24.         return
  25.     }
  26.     resp, err := cli.Get(context.TODO(), "hello")
  27.     if err != nil {
  28.         fmt.Printf("get  etcd failed, %v\n", err)
  29.         return
  30.     }
  31.     for _, kv := range resp.Kvs {
  32.         fmt.Printf("%s:%s\n", kv.Key, kv.Value)
  33.     }
  34.     _, err = cli.Delete(context.TODO(), "hello")
  35.     if err != nil {
  36.         fmt.Printf("get  etcd failed, %v\n", err)
  37.         return
  38.     }
  39. }

前缀搜索

  1. package main
  3. import (
  4.     "context"
  5.     "log"
  6.     "time"
  8.     "go.etcd.io/etcd/clientv3"
  9. )
  11. func main() {
  13.     client, err := clientv3.New(clientv3.Config{
  14.         Endpoints:   []string{"127.0.0.1:2379"}, // 集群列表
  15.         DialTimeout: 5 * time.Second,
  16.     })
  17.     if err != nil {
  18.         log.Fatal(err)
  19.     }
  20.     kv := clientv3.NewKV(client)
  21.     _, err = kv.Put(context.TODO(), "/config/hello/dev", "etcd")
  22.     if err != nil {
  23.         log.Fatal(err)
  24.     }
  25.     _, err = kv.Put(context.TODO(), "/config/hello/test", "world")
  26.     if err != nil {
  27.         log.Fatal(err)
  28.     }
  29.     res, err := kv.Get(context.TODO(), "/config/hello/", clientv3.WithPrefix())
  30.     if err != nil {
  31.         log.Fatal(err)
  32.     }
  34.     log.Println("Revision:", res.Header.Revision)
  35.     for _, v := range res.Kvs {
  36.         log.Printf("Key=%s,Value=%s\n", string(v.Key), string(v.Value))
  37.     }
  38. }

打印结果

  1. Key=/config/hello/dev,Value=etcd
  2. Key=/config/hello/test,Value=world

watch

  1. package main
  3. import (
  4.     "context"
  5.     "fmt"
  6.     "time"
  8.     "go.etcd.io/etcd/clientv3"
  9. )
  11. func main() {
  12.     cli, err := clientv3.New(clientv3.Config{
  13.         Endpoints:   []string{"127.0.0.1:2379"},
  14.         DialTimeout: 2 * time.Second,
  15.     })
  16.     if err != nil {
  17.         fmt.Printf("connect to etcd failed, err:%v\n", err)
  18.         return
  19.     }
  20.     defer cli.Close()
  21.     wcs := cli.Watch(context.Background(), "hello") // <-chan WatchResponse
  22.     for c := range wcs {
  23.         for _, ev := range c.Events {
  24.             fmt.Printf("Type: %s Key:%s Value:%s\n", ev.Type, ev.Kv.Key, ev.Kv.Value)
  25.         }
  26.     }
  27. }

执行go run watch/main.go
接着执行 go run crud/main.go，在watch/main.go中会出现如下打印

  1. Type: PUT Key:hello Value:etcd
  2. Type: DELETE Key:hello Value:

模拟操作方式

  1. package main
  3. import (
  4.     "context"
  5.     "fmt"
  6.     "log"
  7.     "time"
  9.     "go.etcd.io/etcd/clientv3"
  10.     "go.etcd.io/etcd/mvcc/mvccpb"
  11. )
  13. func main() {
  15.     client, err := clientv3.New(clientv3.Config{
  16.         Endpoints:   []string{"127.0.0.1:2379"}, // 集群列表
  17.         DialTimeout: 5 * time.Second,
  18.     })
  19.     if err != nil {
  20.         log.Fatal(err)
  21.     }
  23.     // 模拟etcd中kv的变化
  24.     go func() {
  25.         for {
  26.             client.Put(context.TODO(), "hello", "world")
  28.             client.Delete(context.TODO(), "hello")
  29.             time.Sleep(2 * time.Second)
  30.         }
  31.     }()
  33.     // 启动监听 5秒后关闭
  34.     ctx, cancelFunc := context.WithCancel(context.TODO())
  35.     time.AfterFunc(10*time.Second, func() {
  36.         cancelFunc()
  37.     })
  38.     watchRespChan := client.Watch(ctx, "hello")
  40.     // 处理kv变化事件
  41.     for watchResp := range watchRespChan {
  42.         for _, event := range watchResp.Events {
  43.             switch event.Type {
  44.             case mvccpb.PUT:
  45.                 fmt.Println("put action", string(event.Kv.Value))
  46.             case mvccpb.DELETE:
  47.                 fmt.Println("delete action", string(event.Kv.Key))
  48.             }
  49.         }
  50.     }
  51. }

租约

  1. package main
  3. import (
  4.     "context"
  5.     "log"
  6.     "time"
  8.     "go.etcd.io/etcd/clientv3"
  9. )
  11. func main() {
  13.     client, err := clientv3.New(clientv3.Config{
  14.         Endpoints:   []string{"127.0.0.1:2379"}, // 集群列表
  15.         DialTimeout: 5 * time.Second,
  16.     })
  17.     if err != nil {
  18.         log.Fatal(err)
  19.     }
  21.     grant, err := client.Grant(context.TODO(), 10)
  22.     if err != nil {
  23.         log.Fatal(err)
  24.     }
  25.     k := "config/dev/hello"
  26.     _, err = client.Put(context.TODO(),
  27.         k,
  28.         "etcd",
  29.         clientv3.WithLease(grant.ID),
  30.     )
  31.     if err != nil {
  32.         log.Fatal(err)
  33.     }
  34.     var res *clientv3.GetResponse
  35.     for {
  36.         if res, err = client.Get(context.TODO(), k); err != nil {
  37.             log.Println(err)
  38.             return
  39.         }
  40.         if res.Count == 0 {
  41.             log.Println("kv已过期")
  42.             return
  43.         }
  44.         log.Println("key未过期")
  45.         time.Sleep(2 * time.Second)
  46.     }
  47. }

参考

https://github.com/etcd-io/etcd/issues/12464
https://github.com/etcd-io/etcd/issues/11772
https://colobu.com/2020/04/09/accidents-of-etcd-and-go-module/