四、服务注册与发现
环境依赖
- 安装并且启动etcd
- 按照etcd SDK
go get go.etcd.io/etcd/client/v3@v3.5.4 go get google.golang.org/grpc@v1.48.0
旧版本grpc与etcd可能存在不兼容问题，建议使用最新兼容版本
服务注册与发现
实现思路：服务端启动服务时将自己的服务信息如IP、端口、版本等信息注册到注册中心（此处为ETCD），客户端在进行服务调用时会以约定好的服务名到注册中心查询，发现具体可以调用的服务。 服务端实现：
func init() {
flag.StringVar(&port, "p", "8000", "启动端口号")
flag.Parse()
}
func main() {
server := grpc.NewServer()
discover.RegisterDiscoverDemoServer(server, &DiscoverDemo{})
reflection.Register(server)
taget := fmt.Sprintf("grpc-demo/grpc/%s", types.SERVER_NAME)
client, err := etcd3.New(etcd3.Config{
Endpoints: []string{"http://127.0.0.1:2379"},
})
if err != nil {
panic(err)
}
addr := "127.0.0.1:"+port
err = register.EtcdAdd(client, taget,addr)
if err != nil {
return
}
lis, _ := net.Listen("tcp", addr)
server.Serve(lis)
}
register.EtcdAdd 方法实现
func EtcdAdd(c *clientv3.Client, service, addr string) error {
em, _ := endpoints.NewManager(c, service)
list, _ := em.List(c.Ctx())
fmt.Println(list)
return em.AddEndpoint(c.Ctx(), service+"/"+addr, endpoints.Endpoint{Addr: addr})
}
此时启动服务
go run server.go -p 8001 go run server.go -p 8002
可以通过 etcdctl 命令查看到注册信息：
客户端实现：
func main() {
cli, _ := clientv3.NewFromURL("http://127.0.0.1:2379")
taget := "grpc-demo/grpc/discover-demo"
n := 0
for {
conn, err := register.EtcdDial(cli, taget)
if err != nil {
panic(err)
}
defer conn.Close()
client := discover.NewDiscoverDemoClient(conn)
reply, err := client.Discover(context.Background(), &discover.Request{Name: "DDDD"})
if err != nil {
panic(err)
}
fmt.Printf("%d: %v \n", n, reply)
n++
time.Sleep(time.Second)
}
}
//register.EtcdDial
func EtcdDial(c *clientv3.Client, service string) (*grpc.ClientConn, error) {
etcdResolver, err := resolver.NewBuilder(c)
if err != nil {
return nil, err
}
opts := []grpc.DialOption{
grpc.WithTransportCredentials(insecure.NewCredentials()),
grpc.WithResolvers(etcdResolver),
}
return grpc.Dial("etcd:///"+service, opts...)
}
启动客户端
0: content:“request content from8001 => DDDD” 1: content:“request content from8001 => DDDD” 2: content:“request content from8001 => DDDD” 3: content:“request content from8001 => DDDD” 4: content:“request content from8002 => DDDD” 5: content:“request content from8001 => DDDD”
至此我们实现了服务端的注册，但停掉服务后会发现etcd中的注册信息并没有注销；实际服务端还应该实现服务的定期检测以及主动下线功能； 服务停止是主动下线：
// server.go
go server.Serve(lis)
quit := make(chan os.Signal)
signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)
<-quit
log.Println("Shotdown Server ...")
_ = register.EtcdDelete(client, taget, addr)
//register.EtcdDelete
func EtcdDelete(c *clientv3.Client, service, addr string) error {
em, _ := endpoints.NewManager(c, service)
return em.DeleteEndpoint(c.Ctx(), service+"/"+addr)
}
同时可以通过ETCD设置租期，和定时更新实现定时检查和异常自动下线
func EtcdKeepAlive(c *clientv3.Client, service, addr string, ttl int64) error {
target := service + "/" + addr
go func() {
ticker := time.NewTicker(time.Second * 10)
for {
grant, err := c.Grant(c.Ctx(), ttl)
if err != nil {
log.Println(err)
}
em, _ := endpoints.NewManager(c, service)
update := endpoints.NewAddUpdateOpts(target, endpoints.Endpoint{Addr: addr}, clientv3.WithLease(grant.ID))
err = em.Update(c.Ctx(), []*endpoints.UpdateWithOpts{update})
if err != nil {
log.Println(err)
}
log.Println("update")
select {
case <-stopSignal:
return
case <-ticker.C:
}
}
}()
return nil
}
func EtcdDelete(c *clientv3.Client, service, addr string) error {
close(stopSignal)
em, _ := endpoints.NewManager(c, service)
return em.DeleteEndpoint(c.Ctx(), service+"/"+addr)
}
Reference
