实现etcd服务注册与发现
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0.1、目录结构
.
├── 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
项目根目录下创建etcd目录，并在目录下新增Dockerfile文件
FROM bitnami/etcd:latest
LABEL maintainer="liuyuede123 <liufutianoppo@163.com>"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 # 指定构建使用的 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 # 指定构建使用的 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 # 指定构建使用的 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相关参数概念：
- 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。因此这个地址必须是可以连接集群中所有的成员的。
- ETCD_LISTEN_PEER_URLS：该节点与其他节点通信时所监听的地址列表，多个地址使用逗号隔开，其格式可以划分为scheme://IP:PORT，这里的scheme可以是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：广播给集群中其他成员自己的客户端地址列表
- ETCD_INITIAL_CLUSTER_TOKEN：初始化集群token
- ETCD_INITIAL_CLUSTER：配置集群内部所有成员地址，其格式为：ETCD_NAME=ETCD_INITIAL_ADVERTISE_PEER_URLS，如果有多个使用逗号隔开
- ETCD_INITIAL_CLUSTER_STATE：初始化集群状态，new表示新建
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
liuyuedeetcd集群采用的是raft协议，一般至少为俩个集群，只有一个master，如果删除到只剩一个节点当前节点也不能提供服务
查看集群情况
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、增加服务注册功能
服务注册的流程
- 向etcd新增一个包含rpc服务信息的键值对，并设置租约（比如5秒过期）
- 利用保活函数KeepAlive不断续约
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: // 服务端关闭返回错误
return err
case <-s.client.Ctx().Done(): // etcd关闭
return errors.New("server closed")
case _, ok := <-alive:
if !ok { // 保活通道关闭
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)
// 创建租约
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)
}
// 取消租约
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、增加服务发现
服务发现流程
- 实现grpc中resolver.Builder接口的Build方法
- 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 包含与 ClientConn 相关的当前 Resolver 状态，包括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("缺少port参数：port=8400")
}
for _, arg := range args {
ports := strings.Split(arg, "=")
if len(ports) < 2 || ports[0] != "port" {
panic("port参数格式错误：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("添加到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注册中心和grpc服务建立连接
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建立连接失败：", 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，可以看到客户端通过负载均衡随机到一个服务请求
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本作品采用《CC 协议》，转载必须注明作者和本文链接
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