微服务之服务注册和服务发现篇

JavaMonsterr

墨衍会员 · AI 创作全网分发码龄4年

关注

原创最新推荐文章于 2026-03-08 05:44:31 发布 436 阅读 AI 写同款· GEO 优化 ›

Redis实现服务注册与服务发现源码阅读（Go语言）服务注册与服务发现redis方案源码解读阅读详情

有了服务注册和发现机制，消费者不需要知道具体服务提供者的真实物理地址就可以进行调用，也无须知道具体有多少个服务者可用；而服务提供者只需要注册到注册中心，就可以对外提供服务，在对外服务时不需要知道具体是哪些服务调用了自己。

RPC 配置

Etcd:
  Hosts:
  - 127.0.0.1:2379
  Key: user.rpc

这里分析go-zero 的etcd 部分源码, 源码引用https://github.com/zeromicro/go-zero-demo/tree/master/mall

被调方-服务注册

mall/user/rpc/user.go 源码如下

package main

import (
    "flag"
    "fmt"

    "go-zero-demo-rpc/mall/user/rpc/internal/config"
    "go-zero-demo-rpc/mall/user/rpc/internal/server"
    "go-zero-demo-rpc/mall/user/rpc/internal/svc"
    "go-zero-demo-rpc/mall/user/rpc/types/user"

    "github.com/zeromicro/go-zero/core/conf"
    "github.com/zeromicro/go-zero/core/service"
    "github.com/zeromicro/go-zero/zrpc"
    "google.golang.org/grpc"
    "google.golang.org/grpc/reflection"
)

var configFile = flag.String("f", "etc/user.yaml", "the config file")

func main() {
    flag.Parse()
    
    var c config.Config
    conf.MustLoad(*configFile, &c)
    ctx := svc.NewServiceContext(c)
    svr := server.NewUserServer(ctx)
    
    s := zrpc.MustNewServer(c.RpcServerConf, func(grpcServer *grpc.Server) {
        user.RegisterUserServer(grpcServer, svr)
    
        if c.Mode == service.DevMode || c.Mode == service.TestMode {
            reflection.Register(grpcServer)
        }
    })
    defer s.Stop()
    
    fmt.Printf("Starting rpc server at %s...\n", c.ListenOn)
    s.Start()
}

MustNewServer 内部实现调用了NewServer 方法, 这里我们关注NewServer 通过internal.NewRpcPubServer 方法实例化了internal.Server

if c.HasEtcd() {
    server, err = internal.NewRpcPubServer(c.Etcd, c.ListenOn, serverOptions...)
    if err != nil {
        return nil, err
    }
}

internal.NewRpcPubServer 中的registerEtcd 会调用Publisher.KeepAlive 方法

// KeepAlive keeps key:value alive.
func (p *Publisher) KeepAlive() error {
    // 这里获取 etcd 的连接
    cli, err := internal.GetRegistry().GetConn(p.endpoints)
    if err != nil {
        return err
    }
    
    p.lease, err = p.register(cli)
    if err != nil {
        return err
    }
    
    proc.AddWrapUpListener(func() {
        p.Stop()
    })
    
    return p.keepAliveAsync(cli)
}

p.register 这里把自己注册到服务中

func (p *Publisher) register(client internal.EtcdClient) (clientv3.LeaseID, error) {

    // 这里新建一个租约
    resp, err := client.Grant(client.Ctx(), TimeToLive)
    if err != nil {
        return clientv3.NoLease, err
    }
    
    // 得到租约的 ID
    lease := resp.ID
    
    // 这里拼接出实际存储的 key
    if p.id > 0 {
        p.fullKey = makeEtcdKey(p.key, p.id)
    } else {
        p.fullKey = makeEtcdKey(p.key, int64(lease))
    }

    // p.value 是前面的 figureOutListenOn 方法获取到自己的地址
    _, err = client.Put(client.Ctx(), p.fullKey, p.value, clientv3.WithLease(lease))

    return lease, err
}

注册完之后,keepAliveAsync 开了一个协程保活这个服务
当这个服务意外宕机时, 就不会再向etcd 保活,etcd 就会删除这个key
注册好的服务如图

1.png

调用方-服务发现

order/api/order.go 源码如下

package main

import (
  "flag"
  "fmt"

  "go-zero-demo-rpc/order/api/internal/config"
  "go-zero-demo-rpc/order/api/internal/handler"
  "go-zero-demo-rpc/order/api/internal/svc"

  "github.com/zeromicro/go-zero/core/conf"
  "github.com/zeromicro/go-zero/rest"
)

var configFile = flag.String("f", "etc/order.yaml", "the config file")

func main() {
  flag.Parse()

  var c config.Config
  conf.MustLoad(*configFile, &c)

  server := rest.MustNewServer(c.RestConf)
  defer server.Stop()

  ctx := svc.NewServiceContext(c)
  handler.RegisterHandlers(server, ctx)

  fmt.Printf("Starting server at %s:%d...\n", c.Host, c.Port)
  server.Start()
}

在svc.NewServiceContext 方法内部又调用了zrpc.MustNewClient ,zrpc.MustNewClient 主要实现在zrpc.NewClient

func NewServiceContext(c config.Config) *ServiceContext {
  return &ServiceContext{
    Config:  c,
    UserRpc: user.NewUser(zrpc.MustNewClient(c.UserRpc)),
  }
}

最后实际调用了internal.NewClient 去实例化rpc client

func NewClient(c RpcClientConf, options ...ClientOption) (Client, error) {
  var opts []ClientOption
  if c.HasCredential() {
    opts = append(opts, WithDialOption(grpc.WithPerRPCCredentials(&auth.Credential{
      App:   c.App,
      Token: c.Token,
    })))
  }
  if c.NonBlock {
    opts = append(opts, WithNonBlock())
  }
  if c.Timeout > 0 {
    opts = append(opts, WithTimeout(time.Duration(c.Timeout)*time.Millisecond))
  }

  opts = append(opts, options...)

  target, err := c.BuildTarget()
  if err != nil {
    return nil, err
  }

  client, err := internal.NewClient(target, opts...)
  if err != nil {
    return nil, err
  }

  return &RpcClient{
    client: client,
  }, nil
}

在zrpc/internal/client.go 文件里, 包含一个init 方法, 这里就是实际发现服务的地方, 在这里注册服务发现者

func init() {
  resolver.Register()
}

resolver.Register 方法实现

package resolver

import (
  "github.com/zeromicro/go-zero/zrpc/resolver/internal"
)

// Register registers schemes defined zrpc.
// Keep it in a separated package to let third party register manually.
func Register() {
  internal.RegisterResolver()
}

最后又回到interval 包的internal.RegisterResolver 方法, 这里我们关注etcdResolverBuilder

func RegisterResolver() {
  resolver.Register(&directResolverBuilder)
  resolver.Register(&discovResolverBuilder)
  resolver.Register(&etcdResolverBuilder)
  resolver.Register(&k8sResolverBuilder)
}

etcdBuilder 的内嵌了discovBuilder 结构体,

Build 方法调用过程:
实例化服务端:internal.NewClient ->client.dial ->grpc.DialContext
由于etcd 是resolver.BuildDiscovTarget 生成的taget 所以是类似这样子的:discov://127.0.0.1:2379/user.rpc
解析服务发现:ClientConn.parseTargetAndFindResolver ->grpc.parseTarget ->ClientConn.getResolver
然后在grpc.newCCResolverWrapper 调用resolver.Builder.Build 方法去发现服务

我们着重关注discovBuilder.Build 方法

type etcdBuilder struct {
  discovBuilder
}


type discovBuilder struct{}

func (b *discovBuilder) Build(target resolver.Target, cc resolver.ClientConn, _ resolver.BuildOptions) (
  resolver.Resolver, error) {
  hosts := strings.FieldsFunc(targets.GetAuthority(target), func(r rune) bool {
    return r == EndpointSepChar
  })
  sub, err := discov.NewSubscriber(hosts, targets.GetEndpoints(target))
  if err != nil {
    return nil, err
  }

  update := func() {
    var addrs []resolver.Address
    for _, val := range subset(sub.Values(), subsetSize) {
      addrs = append(addrs, resolver.Address{
        Addr: val,
      })
    }
    if err := cc.UpdateState(resolver.State{
      Addresses: addrs,
    }); err != nil {
      logx.Error(err)
    }
  }
  sub.AddListener(update)
  update()

  return &nopResolver{cc: cc}, nil
}

func (b *discovBuilder) Scheme() string {
  return DiscovScheme
}

discov.NewSubscriber 方法调用internal.GetRegistry().Monitor 最后调用Registry.monitor 方法进行监视

cluster.getClient 拿到etcd 连接

cluster.load 作为第一次载入数据

cluster.watch 去watch 监听etcd 前缀key 的改动

func (c *cluster) monitor(key string, l UpdateListener) error {
  c.lock.Lock()
  c.listeners[key] = append(c.listeners[key], l)
  c.lock.Unlock()

  cli, err := c.getClient()
  if err != nil {
    return err
  }

  c.load(cli, key)
  c.watchGroup.Run(func() {
    c.watch(cli, key)
  })

  return nil
}