关于etcd:实现etcd服务注册与发现

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转载自：实现 etcd 服务注册与发现

0.1、目录构造 

.
├── api
│   └── main.go
├── common
│   └── common.go
├── docker-compose.yml
├── etcd
│   └── Dockerfile
├── go.mod
├── go.sum
├── rpc
│   ├── courseware
│   │   ├── courseware.pb.go
│   │   └── courseware_grpc.pb.go
│   ├── courseware.proto
│   └── main.go
└── server
    ├── service_discovery.go
    └── service_registration.go

1、docker-compose 部署一个 3 节点的集群

我的项目根目录下创立 etcd 目录，并在目录下新增 Dockerfile 文件 

FROM bitnami/etcd:latest

LABEL maintainer="liuyuede123 <liufutianoppo@163.com>"

我的项目根目录下新增 docker-compose.yml

version: '3.5'
# 网络配置
networks:
  backend:
    driver: bridge

# 服务容器配置
services:
  etcd1:                                  # 自定义容器名称
    build:
      context: etcd                    # 指定构建应用的 Dockerfile 文件
    environment:
      - TZ=Asia/Shanghai
      - ALLOW_NONE_AUTHENTICATION=yes
      - ETCD_NAME=etcd1
      - ETCD_INITIAL_ADVERTISE_PEER_URLS=http://etcd1:2380
      - ETCD_LISTEN_PEER_URLS=http://0.0.0.0:2380
      - ETCD_LISTEN_CLIENT_URLS=http://0.0.0.0:2379
      - ETCD_ADVERTISE_CLIENT_URLS=http://etcd1:2379
      - ETCD_INITIAL_CLUSTER_TOKEN=etcd-cluster
      - ETCD_INITIAL_CLUSTER=etcd1=http://etcd1:2380,etcd2=http://etcd2:2380,etcd3=http://etcd3:2380
      - ETCD_INITIAL_CLUSTER_STATE=new
    ports:                               # 设置端口映射
      - "12379:2379"
      - "12380:2380"
    networks:
      - backend
    restart: always

  etcd2: # 自定义容器名称
    build:
      context: etcd                    # 指定构建应用的 Dockerfile 文件
    environment:
      - TZ=Asia/Shanghai
      - ALLOW_NONE_AUTHENTICATION=yes
      - ETCD_NAME=etcd2
      - ETCD_INITIAL_ADVERTISE_PEER_URLS=http://etcd2:2380
      - ETCD_LISTEN_PEER_URLS=http://0.0.0.0:2380
      - ETCD_LISTEN_CLIENT_URLS=http://0.0.0.0:2379
      - ETCD_ADVERTISE_CLIENT_URLS=http://etcd2:2379
      - ETCD_INITIAL_CLUSTER_TOKEN=etcd-cluster
      - ETCD_INITIAL_CLUSTER=etcd1=http://etcd1:2380,etcd2=http://etcd2:2380,etcd3=http://etcd3:2380
      - ETCD_INITIAL_CLUSTER_STATE=new
    ports: # 设置端口映射
      - "22379:2379"
      - "22380:2380"
    networks:
      - backend
    restart: always

  etcd3: # 自定义容器名称
    build:
      context: etcd                    # 指定构建应用的 Dockerfile 文件
    environment:
      - TZ=Asia/Shanghai
      - ALLOW_NONE_AUTHENTICATION=yes
      - ETCD_NAME=etcd3
      - ETCD_INITIAL_ADVERTISE_PEER_URLS=http://etcd3:2380
      - ETCD_LISTEN_PEER_URLS=http://0.0.0.0:2380
      - ETCD_LISTEN_CLIENT_URLS=http://0.0.0.0:2379
      - ETCD_ADVERTISE_CLIENT_URLS=http://etcd3:2379
      - ETCD_INITIAL_CLUSTER_TOKEN=etcd-cluster
      - ETCD_INITIAL_CLUSTER=etcd1=http://etcd1:2380,etcd2=http://etcd2:2380,etcd3=http://etcd3:2380
      - ETCD_INITIAL_CLUSTER_STATE=new
    ports: # 设置端口映射
      - "32379:2379"
      - "32380:2380"
    networks:
      - backend
    restart: always

相干参数概念：

  1. ETCD_INITIAL_ADVERTISE_PEER_URLS：该成员节点在整个集群中的通信地址列表，这个地址用来传输集群数据的地址。因而这个地址必须是能够连贯集群中所有的成员的。
  2. ETCD_LISTEN_PEER_URLS：该节点与其余节点通信时所监听的地址列表，多个地址应用逗号隔开，其格局能够划分为 scheme://IP:PORT，这里的 scheme 能够是 http、https
  3. ETCD_LISTEN_CLIENT_URLS：该节点与客户端通信时监听的地址列表
  4. ETCD_ADVERTISE_CLIENT_URLS：播送给集群中其余成员本人的客户端地址列表
  5. ETCD_INITIAL_CLUSTER_TOKEN：初始化集群 token
  6. ETCD_INITIAL_CLUSTER：配置集群外部所有成员地址，其格局为：ETCD_NAME=ETCD_INITIAL_ADVERTISE_PEER_URLS，如果有多个应用逗号隔开
  7. ETCD_INITIAL_CLUSTER_STATE：初始化集群状态，new 示意新建

启动集群 

docker-compose up -d
Creating network "etcd_backend" with driver "bridge"
Creating etcd_etcd1_1 ... done
Creating etcd_etcd2_1 ... done
Creating etcd_etcd3_1 ... done

测试集群可用性 

# 登录其中一个节点
docker exec -it 5f97bf0b446f6e6514576fc1eb46c2f60d2c2b3e3f3ee3b1ad6219414fa915c8 /bin/sh
# 写入一个键值
etcdctl put name "liuyuede"
OK
# 查看
etcdctl get name
name
liuyuede

# 登录另外俩个节点
docker exec -it a6ccc9b6e5cc81ee7c779e2b9e7235cd6d814e92fbc66b7e4846798acff8ee2a /bin/sh
etcdctl get name
name
liuyuede

docker exec -it 6817fa89e3e9e422628e0049910b672df389c62d41bf2349a0f77e22c99e5270 /bin/sh
etcdctl get name
name
liuyuede

etcd 集群采纳的是 raft 协定，个别至多为俩个集群，只有一个 master，如果删除到只剩一个节点以后节点也不能提供服务

查看集群状况 

etcdctl --endpoints=http://0.0.0.0:12379,0.0.0.0:22379,0.0.0.0:32379 endpoint status --write-out=table

+----------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+
|       ENDPOINT       |        ID        | VERSION | DB SIZE | IS LEADER | IS LEARNER | RAFT TERM | RAFT INDEX | RAFT APPLIED INDEX | ERRORS |
+----------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+
| http://0.0.0.0:12379 | ade526d28b1f92f7 |   3.5.4 |   20 kB |      true |      false |         3 |         13 |                 13 |        |
|        0.0.0.0:22379 | d282ac2ce600c1ce |   3.5.4 |   20 kB |     false |      false |         3 |         13 |                 13 |        |
|        0.0.0.0:32379 | bd388e7810915853 |   3.5.4 |   20 kB |     false |      false |         3 |         13 |                 13 |        |
+----------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+

2、减少服务注册性能

服务注册的流程

  1. 向 etcd 新增一个蕴含 rpc 服务信息的键值对，并设置租约（比方 5 秒过期）
  2. 利用保活函数 KeepAlive 一直续约 
package server

import (
    "context"
    "encoding/json"
    "errors"
    clientv3 "go.etcd.io/etcd/client/v3"
    "time"
)

type ServiceInfo struct {
    Name string
    Ip   string
}

type Service struct {
    ServiceInfo ServiceInfo
    stop        chan error
    leaseId     clientv3.LeaseID
    client      *clientv3.Client
}

func NewService(serviceInfo ServiceInfo, endpoints []string) (service *Service, err error) {
    client, err := clientv3.New(clientv3.Config{
        Endpoints:   endpoints,
        DialTimeout: time.Second * 10,
    })
    if err != nil {return nil, err}

    service = &Service{
        ServiceInfo: serviceInfo,
        client:      client,
    }
    return
}

func (s *Service) Start(ctx context.Context) (err error) {alive, err := s.KeepAlive(ctx)
    if err != nil {return}

    for {
        select {
        case err = <-s.stop: // 服务端敞开返回谬误
            return err
        case <-s.client.Ctx().Done(): // etcd 敞开
            return errors.New("server closed")
        case _, ok := <-alive:
            if !ok { // 保活通道敞开
                return s.revoke(ctx)
            }
        }
    }
}

func (s *Service) KeepAlive(ctx context.Context) (<-chan *clientv3.LeaseKeepAliveResponse, error) {
    info := s.ServiceInfo
    key := s.getKey()
    val, _ := json.Marshal(info)

    // 创立租约
    leaseResp, err := s.client.Grant(ctx, 5)
    if err != nil {return nil, err}

    // 写入 etcd
    _, err = s.client.Put(ctx, key, string(val), clientv3.WithLease(leaseResp.ID))
    if err != nil {return nil, err}

    s.leaseId = leaseResp.ID
    return s.client.KeepAlive(ctx, leaseResp.ID)
}

// 勾销租约
func (s *Service) revoke(ctx context.Context) error {_, err := s.client.Revoke(ctx, s.leaseId)
    return err
}

func (s *Service) getKey() string {return s.ServiceInfo.Name + "/" + s.ServiceInfo.Ip}

3、减少服务发现

服务发现流程

  1. 实现 grpc 中 resolver.Builder 接口的 Build 办法
  2. 通过 etcdclient 获取并监听 grpc 服务（是否有新增或者删除）
  3. 更新到 resolver.State，State 蕴含与 ClientConn 相干的以后 Resolver 状态，包含 grpc 的地址 resolver.Address
package server

import (
    "context"
    "encoding/json"
    "fmt"
    "go.etcd.io/etcd/api/v3/mvccpb"
    clientv3 "go.etcd.io/etcd/client/v3"
    "google.golang.org/grpc/resolver"
)

type Discovery struct {endpoints  []string
    service    string
    client     *clientv3.Client
    clientConn resolver.ClientConn
}

func NewDiscovery(endpoints []string, service string) resolver.Builder {
    return &Discovery{
        endpoints: endpoints,
        service:   service,
    }
}

func (d *Discovery) ResolveNow(rn resolver.ResolveNowOptions) {

}

func (d *Discovery) Close() {}

func (d *Discovery) Build(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOptions) (resolver.Resolver, error) {
    var err error
    d.client, err = clientv3.New(clientv3.Config{Endpoints: d.endpoints,})
    if err != nil {return nil, err}

    d.clientConn = cc

    go d.watch(d.service)

    return d, nil
}

func (d *Discovery) Scheme() string {return "etcd"}

func (d *Discovery) watch(service string) {addrM := make(map[string]resolver.Address)
    state := resolver.State{}

    update := func() {addrList := make([]resolver.Address, 0, len(addrM))
        for _, address := range addrM {addrList = append(addrList, address)
        }
        state.Addresses = addrList
        err := d.clientConn.UpdateState(state)
        if err != nil {fmt.Println("更新地址出错：", err)
        }
    }
    resp, err := d.client.Get(context.Background(), service, clientv3.WithPrefix())
    if err != nil {fmt.Println("获取地址出错：", err)
    } else {
        for i, kv := range resp.Kvs {info := &ServiceInfo{}
            err = json.Unmarshal(kv.Value, info)
            if err != nil {fmt.Println("解析 value 失败：", err)
            }
            addrM[string(resp.Kvs[i].Key)] = resolver.Address{
                Addr:       info.Ip,
                ServerName: info.Name,
            }
        }
    }

    update()

    dch := d.client.Watch(context.Background(), service, clientv3.WithPrefix(), clientv3.WithPrevKV())
    for response := range dch {
        for _, event := range response.Events {
            switch event.Type {
            case mvccpb.PUT:
                info := &ServiceInfo{}
                err = json.Unmarshal(event.Kv.Value, info)
                if err != nil {fmt.Println("监听时解析 value 报错：", err)
                } else {addrM[string(event.Kv.Key)] = resolver.Address{Addr: info.Ip}
                }
                fmt.Println(string(event.Kv.Key))
            case mvccpb.DELETE:
                delete(addrM, string(event.Kv.Key))
                fmt.Println(string(event.Kv.Key))
            }
        }
        update()}
}

4、grpc 课件服务

common 参数 

package common

const CoursewareRpc = "rpc.courseware"

var Endpoints = []string{"127.0.0.1:12379", "127.0.0.1:22379", "127.0.0.1:32379"}

生成课件服务 grpc

syntax = "proto3";

package rpc;
option go_package = "./courseware";

message GetRequest {uint64 Id = 1;}
message GetResponse {
  uint64 Id = 1;
  string Code = 2;
  string Name = 3;
  uint64 Type = 4;
}


service Courseware {rpc Get(GetRequest) returns(GetResponse);
}
protoc --go_out=./ --go-grpc_out=./ courseware.proto

课件服务入口 

package main

import (
    "context"
    "fmt"
    "go-demo/etcd/common"
    "go-demo/etcd/rpc/courseware"
    "go-demo/etcd/server"
    "google.golang.org/grpc"
    "google.golang.org/grpc/reflection"
    "net"
    "os"
    "strings"
    "time"
)

var Port string

type service struct {courseware.UnsafeCoursewareServer}

func (s *service) Get(ctx context.Context, req *courseware.GetRequest) (res *courseware.GetResponse, err error) {fmt.Println("获取课件详情 port:", Port, "time:", time.Now())
    return &courseware.GetResponse{
        Id:   1,
        Code: "HD4544",
        Name: "多媒体课件",
        Type: 4,
    }, nil
}
func main() {args := os.Args[1:]
    if len(args) == 0 {panic("短少 port 参数：port=8400")
    }
    for _, arg := range args {ports := strings.Split(arg, "=")
        if len(ports) < 2 || ports[0] != "port" {panic("port 参数格局谬误：port=8400")
        }
        Port = ports[1]
    }
    listen, err := net.Listen("tcp", ":"+Port)
    if err != nil {fmt.Println("failed to listen", err)
        return
    }
    s := grpc.NewServer()
    courseware.RegisterCoursewareServer(s, &service{})

    reflection.Register(s)

  // 注册到 etcd
    newService, err := server.NewService(server.ServiceInfo{
        Name: common.CoursewareRpc,
        Ip:   "127.0.0.1:" + Port,
    }, common.Endpoints)
    if err != nil {fmt.Println("增加到 etcd 失败：", err)
        return
    }

    go func() {err = newService.Start(context.Background())
        if err != nil {fmt.Println("开启服务注册失败：", err)
        }
    }()

    if err = s.Serve(listen); err != nil {fmt.Println("开启 rpc 服务失败：", err)
    }
}

5、api 服务 

package main

import (
    "context"
    "fmt"
    "go-demo/etcd/common"
    "go-demo/etcd/rpc/courseware"
    "go-demo/etcd/server"
    "google.golang.org/grpc"
    "google.golang.org/grpc/credentials/insecure"
    "google.golang.org/grpc/resolver"
    "time"
)

func main() {d := server.NewDiscovery(common.Endpoints, common.CoursewareRpc)
    resolver.Register(d)

    for {ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
    // 通过 etcd 注册核心和 grpc 服务建设连贯
        conn, err := grpc.DialContext(ctx,
            fmt.Sprintf(d.Scheme()+":///"+common.CoursewareRpc),
            grpc.WithTransportCredentials(insecure.NewCredentials()),
            grpc.WithDefaultServiceConfig(`{"loadBalancingConfig": [{"round_robin":{}}]}`),
            grpc.WithBlock(),)
        if err != nil {fmt.Println("和 rpc 建设连贯失败：", err)
            return
        }

        client := courseware.NewCoursewareClient(conn)
        get, err := client.Get(ctx, &courseware.GetRequest{Id: 1})
        if err != nil {fmt.Println("获取课件失败：", err)
            return
        }

        fmt.Println(get)

        time.Sleep(3 * time.Second)
        cancel()}

}

6、测试

开启 3 个服务，能够看到客户端通过负载平衡随机到一个服务申请 

go run main.go port=8400
获取课件详情 port: 8400  time: 2022-08-25 18:47:43.784942 +0800 CST m=+78.228450885
获取课件详情 port: 8400  time: 2022-08-25 18:47:52.925858 +0800 CST m=+87.369721731
获取课件详情 port: 8400  time: 2022-08-25 18:48:02.001177 +0800 CST m=+96.445393312
获取课件详情 port: 8400  time: 2022-08-25 18:48:05.060066 +0800 CST m=+99.504401028
获取课件详情 port: 8400  time: 2022-08-25 18:48:14.154148 +0800 CST m=+108.598836458
go run main.go port=8500
获取课件详情 port: 8500  time: 2022-08-25 18:47:46.832479 +0800 CST m=+62.822399701
获取课件详情 port: 8500  time: 2022-08-25 18:47:49.844536 +0800 CST m=+65.834573960
获取课件详情 port: 8500  time: 2022-08-25 18:47:55.955638 +0800 CST m=+71.945912584
获取课件详情 port: 8500  time: 2022-08-25 18:48:17.168293 +0800 CST m=+93.159391485
获取课件详情 port: 8500  time: 2022-08-25 18:48:20.182787 +0800 CST m=+96.174002796
go run main.go port=8600
获取课件详情 port: 8600  time: 2022-08-25 18:47:58.968283 +0800 CST m=+1.317052360
获取课件详情 port: 8600  time: 2022-08-25 18:48:08.106493 +0800 CST m=+10.455617422
获取课件详情 port: 8600  time: 2022-08-25 18:48:11.125212 +0800 CST m=+13.474453269

正文完
etcd
发表至： etcd
2022-08-25
 0
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