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.go1、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:latestLABEL 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：
- 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。
- 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
- ETCD_LISTEN_CLIENT_URLS：该节点与客户端通信时监听的地址列表
- ETCD_ADVERTISE_CLIENT_URLS：播送给集群中其余成员本人的客户端地址列表
- ETCD_INITIAL_CLUSTER_TOKEN：初始化集群token
- 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
- ETCD_INITIAL_CLUSTER_STATE：初始化集群状态，new示意新建
启动集群
docker-compose up -dCreating network "etcd_backend" with driver "bridge"Creating etcd_etcd1_1 ... doneCreating etcd_etcd2_1 ... doneCreating 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 namenameliuyuede# 登录另外俩个节点docker exec -it a6ccc9b6e5cc81ee7c779e2b9e7235cd6d814e92fbc66b7e4846798acff8ee2a /bin/shetcdctl get namenameliuyuededocker exec -it 6817fa89e3e9e422628e0049910b672df389c62d41bf2349a0f77e22c99e5270 /bin/shetcdctl get namenameliuyuedeetcd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
- 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）
- 利用保活函数KeepAlive一直续约
package serverimport ( "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
- 实现grpc中resolver.Builder接口的Build办法
- 通过etcdclient获取并监听grpc服务（是否有新增或者删除）
- 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 serverimport ( "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 commonconst 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 mainimport ( "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 stringtype 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 mainimport ( "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=+108.598836458go 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=+96.174002796go 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