Golang基于etcd实现服务注册和发现功能

简单做个笔记

register

package main
 
import (
	"os"
	"log"
	"time"
	"syscall"
	"context"
	"os/signal"
 
	"go.etcd.io/etcd/clientv3"
)
 
//ServiceRegister 创建租约注册服务
type ServiceRegister struct {
	cli     *clientv3.Client //etcd v3 client
	leaseID clientv3.LeaseID //租约ID
	//租约keepalieve相应chan
	keepAliveChan <-chan *clientv3.LeaseKeepAliveResponse
	key           string //key
	val           string //value
}
 
//NewServiceRegister 新建注册服务
func NewServiceRegister(endpoints []string, key, val string, lease int64,dailTimeout  int) (*ServiceRegister, error) {
	cli, err := clientv3.New(clientv3.Config{
		Endpoints:   endpoints,
		DialTimeout: time.Duration(dailTimeout) * time.Second,
	})
	if err != nil {
		return nil,err
	}
 
	ser := &ServiceRegister{
		cli: cli,
		key: key,
		val: val,
	}
 
	//申请租约设置时间keepalive
	if err := ser.putKeyWithLease(lease); err != nil {
		return nil, err
	}
 
	return ser, nil
}
 
//设置租约
func (s *ServiceRegister) putKeyWithLease(lease int64) error {
	//创建一个新的租约，并设置ttl时间
	resp, err := s.cli.Grant(context.Background(), lease)
	if err != nil {
		return err
	}
 
	//注册服务并绑定租约
	_, err = s.cli.Put(context.Background(), s.key, s.val, clientv3.WithLease(resp.ID))
	if err != nil {
		return err
	}
	//设置续租 定期发送需求请求
	//KeepAlive使给定的租约永远有效。 如果发布到通道的keepalive响应没有立即被使用，
	// 则租约客户端将至少每秒钟继续向etcd服务器发送保持活动请求，直到获取最新的响应为止。
	//etcd client会自动发送ttl到etcd server，从而保证该租约一直有效
	leaseRespChan, err := s.cli.KeepAlive(context.Background(), resp.ID)
	if err != nil {
		return err
	}
 
	s.leaseID = resp.ID
	log.Println(s.leaseID)
	s.keepAliveChan = leaseRespChan
	log.Printf("Put key:%s  val:%s  success!", s.key, s.val)
	return nil
}
 
//ListenLeaseRespChan 监听 续租情况
func (s *ServiceRegister) ListenLeaseRespChan() {
	for leaseKeepResp := range s.keepAliveChan {
		log.Println("续约成功", leaseKeepResp)
	}
	log.Println("关闭续租")
}
 
// Close 注销服务
func (s *ServiceRegister) Close() error {
	//撤销租约
	if _, err := s.cli.Revoke(context.Background(), s.leaseID); err != nil {
		return err
	}
	log.Println("撤销租约")
	return s.cli.Close()
}
 
func main() {
	var endpoints = []string{"localhost:2379"}
 
	ser, err := NewServiceRegister(endpoints, "/server/node1", "localhost:8000", 6 , 5)
	if err != nil {
		log.Fatalln(err)
	}
	//监听续租相应chan
	go ser.ListenLeaseRespChan()
 
	// 监控系统信号，等待 ctrl + c 系统信号通知服务关闭
	c := make(chan os.Signal, 1)
	go func() {
		signal.Notify(c, syscall.SIGINT, syscall.SIGTERM)
	}()
	log.Printf("exit %s", <-c)
	ser.Close()
}

discover

package main
 
import (
	"os"
	"log"
	"time"
	"sync"
	"syscall"
	"context"
	"os/signal"
 
	"go.etcd.io/etcd/clientv3"
	"github.com/coreos/etcd/mvcc/mvccpb"
)
 
//ServiceDiscovery 服务发现
type ServiceDiscovery struct {
	cli        *clientv3.Client  //etcd client
	serverList map[string]string //服务列表
	lock       sync.RWMutex
}
 
//NewServiceDiscovery  新建发现服务
func NewServiceDiscovery(endpoints []string) *ServiceDiscovery {
	//初始化etcd client v3
	cli, err := clientv3.New(clientv3.Config{
		Endpoints:   endpoints,
		DialTimeout: 5 * time.Second,
	})
 
	if err != nil {
		log.Fatal(err)
	}
 
	return &ServiceDiscovery{
		cli:        cli,
		serverList: make(map[string]string),
	}
}
 
//WatchService 初始化服务列表和监视
func (s *ServiceDiscovery) WatchService(prefix string) error {
	//根据前缀获取现有的key
	resp, err := s.cli.Get(context.Background(), prefix, clientv3.WithPrefix())
	if err != nil {
		return err
	}
 
	//遍历获取到的key和value
	for _, ev := range resp.Kvs {
		s.SetServiceList(string(ev.Key), string(ev.Value))
	}
 
	//监视前缀，修改变更的server
	go s.watcher(prefix)
	return nil
}
 
//watcher 监听key的前缀
func (s *ServiceDiscovery) watcher(prefix string) {
	rch := s.cli.Watch(context.Background(), prefix, clientv3.WithPrefix())
	log.Printf("watching prefix:%s now...", prefix)
	for wresp := range rch {
		for _, ev := range wresp.Events {
			switch ev.Type {
			case mvccpb.PUT: //修改或者新增
				s.SetServiceList(string(ev.Kv.Key), string(ev.Kv.Value))
			case mvccpb.DELETE: //删除
				s.DelServiceList(string(ev.Kv.Key))
			}
		}
	}
}
 
//SetServiceList 新增服务地址
func (s *ServiceDiscovery) SetServiceList(key, val string) {
	s.lock.Lock()
	defer s.lock.Unlock()
	s.serverList[key] = string(val)
	log.Println("put key :", key, "val:", val)
}
 
//DelServiceList 删除服务地址
func (s *ServiceDiscovery) DelServiceList(key string) {
	s.lock.Lock()
	defer s.lock.Unlock()
	delete(s.serverList, key)
	log.Println("del key:", key)
}
 
//GetServices 获取服务地址
func (s *ServiceDiscovery) GetServices() []string {
	s.lock.RLock()
	defer s.lock.RUnlock()
	addrs := make([]string, 0,len(s.serverList))
 
	for _, v := range s.serverList {
		addrs = append(addrs, v)
	}
	return addrs
}
 
//Close 关闭服务
func (s *ServiceDiscovery) Close() error {
	return s.cli.Close()
}
 
func main() {
	var endpoints = []string{"localhost:2379"}
	ser := NewServiceDiscovery(endpoints)
	defer ser.Close()
 
	err := ser.WatchService("/server/")
	if err != nil {
		log.Fatal(err)
	}
 
 
	// 监控系统信号，等待 ctrl + c 系统信号通知服务关闭
	c := make(chan os.Signal, 1)
	go func() {
		signal.Notify(c, syscall.SIGINT, syscall.SIGTERM)
	}()
 
	for {
		select {
		case <-time.Tick(10 * time.Second):
			log.Println(ser.GetServices())
		case <-c:
			log.Println("server discovery exit")
			return
		}
	}
}