go语言gRPC负载均衡库grpc-lb的使用

grpc-lb采用客户端进程内负载均衡方式，支持随机、轮询、一致性哈希三种负载均衡策略，并支持服务端权重。可采用etcd或consul做为注册中心。

项目地址：
https://github.com/liyue201/g...

基本架构如图，服务提供者起来后向注册中心注册本身的信息，ip、端口、权重等，并保持心跳。客户端监听注册中心，获取服务器列表，一旦服务器发生变化，客户端立刻更新本地的服务器列表。客户端每一个请求都经过负载均衡策略选择一个合适的服务器去访问。

随机负载均衡客户端例子：

package main

import (
    etcd "github.com/coreos/etcd/client"
    grpclb "github.com/liyue201/grpc-lb"
    "github.com/liyue201/grpc-lb/examples/proto"
    registry "github.com/liyue201/grpc-lb/registry/etcd"
    "golang.org/x/net/context"
    "google.golang.org/grpc"
    "log"
)

func main() {
    etcdConfg := etcd.Config{
        Endpoints: []string{"http://120.24.44.201:4001"},
    }
    r := registry.NewResolver("/grpc-lb", "test", etcdConfg)
    b := grpclb.NewBalancer(r, grpclb.NewRandomSelector())
    c, err := grpc.Dial("", grpc.WithInsecure(), grpc.WithBalancer(b))
    if err != nil {
        log.Printf("grpc dial: %s", err)
        return
    }
    defer c.Close()

    client := proto.NewTestClient(c)
    resp, err := client.Say(context.Background(), &proto.SayReq{Content: "random"})
    if err != nil {
        log.Println(err)
        return
    }
    log.Printf(resp.Content)
}

轮询负载均衡，只需把NewRandomSelector改为NewRoundRobinSelector便可。

package main

import (
    etcd "github.com/coreos/etcd/client"
    grpclb "github.com/liyue201/grpc-lb"
    "github.com/liyue201/grpc-lb/examples/proto"
    registry "github.com/liyue201/grpc-lb/registry/etcd"
    "golang.org/x/net/context"
    "google.golang.org/grpc"
    "log"
)

func main() {
    etcdConfg := etcd.Config{
        Endpoints: []string{"http://120.24.44.201:4001"},
    }
    r := registry.NewResolver("/grpc-lb", "test", etcdConfg)
    b := grpclb.NewBalancer(r, grpclb.NewRoundRobinSelector())
    c, err := grpc.Dial("", grpc.WithInsecure(), grpc.WithBalancer(b))
    if err != nil {
        log.Printf("grpc dial: %s", err)
        return
    }
    defer c.Close()

    client := proto.NewTestClient(c)
    resp, err := client.Say(context.Background(), &proto.SayReq{Content: "round robin"})
    if err != nil {
        log.Println(err)
        return
    }
    log.Printf(resp.Content)

}

一致性哈希负载均衡，须要给每一个请求传一个哈希的参数，这个根据应用场景而定，就是下面这个例子中的hashData。

package main

import (
    "fmt"
    etcd "github.com/coreos/etcd/client"
    grpclb "github.com/liyue201/grpc-lb"
    "github.com/liyue201/grpc-lb/examples/proto"
    registry "github.com/liyue201/grpc-lb/registry/etcd"
    "golang.org/x/net/context"
    "google.golang.org/grpc"
    "log"
    "time"
)

func main() {
    etcdConfg := etcd.Config{
        Endpoints: []string{"http://120.24.44.201:4001"},
    }
    r := registry.NewResolver("/grpc-lb", "test", etcdConfg)
    b := grpclb.NewBalancer(r, grpclb.NewKetamaSelector(grpclb.DefaultKetamaKey))
    c, err := grpc.Dial("", grpc.WithInsecure(), grpc.WithBalancer(b), grpc.WithTimeout(time.Second))
    if err != nil {
        log.Printf("grpc dial: %s", err)
        return
    }
    client := proto.NewTestClient(c)

    for i := 0; i < 10; i++ {
        ctx := context.Background()

        hashData := fmt.Sprintf("aaaa %d", i)
        resp, err := client.Say(context.WithValue(ctx, grpclb.DefaultKetamaKey, hashData),
            &proto.SayReq{Content: "ketama"})
        if err != nil {
            log.Println(err)
            time.Sleep(time.Second)
            continue
        }
        log.Printf(resp.Content)
        time.Sleep(time.Second)
    }
}

服务端的代码以下， 使用如下命令运行3个服务进程，再启动客户端。
go run main.go -node node1 -port 28544
go run main.go -node node2 -port 18562
go run main.go -node node3 -port 27772

package main

import (
    "flag"
    "fmt"
    etcd "github.com/coreos/etcd/client"
    "github.com/liyue201/grpc-lb/examples/proto"
    registry "github.com/liyue201/grpc-lb/registry/etcd"
    "golang.org/x/net/context"
    "google.golang.org/grpc"
    "log"
    "net"
    "sync"
    "time"
)

var nodeID = flag.String("node", "node1", "node ID")
var port = flag.Int("port", 8080, "listening port")

type RpcServer struct {
    addr string
    s    *grpc.Server
}

func NewRpcServer(addr string) *RpcServer {
    s := grpc.NewServer()
    rs := &RpcServer{
        addr: addr,
        s:    s,
    }
    return rs
}

func (s *RpcServer) Run() {
    listener, err := net.Listen("tcp", s.addr)
    if err != nil {
        log.Printf("failed to listen: %v", err)
        return
    }
    log.Printf("rpc listening on:%s", s.addr)

    proto.RegisterTestServer(s.s, s)
    s.s.Serve(listener)
}

func (s *RpcServer) Stop() {
    s.s.GracefulStop()
}

func (s *RpcServer) Say(ctx context.Context, req *proto.SayReq) (*proto.SayResp, error) {
    text := "Hello " + req.Content + ", I am " + *nodeID
    log.Println(text)

    return &proto.SayResp{Content: text}, nil
}

func StartService() {
    etcdConfg := etcd.Config{
        Endpoints: []string{"http://120.24.44.201:4001"},
    }

    registry, err := registry.NewRegistry(
        registry.Option{
            EtcdConfig:  etcdConfg,
            RegistryDir: "/grpc-lb",
            ServiceName: "test",
            NodeID:      *nodeID,
            NData: registry.NodeData{
                Addr: fmt.Sprintf("127.0.0.1:%d", *port),
                //Metadata: map[string]string{"weight": "1"}, //这里配置权重，不配置默认是1
            },
            Ttl: 10 * time.Second,
        })
    if err != nil {
        log.Panic(err)
        return
    }
    server := NewRpcServer(fmt.Sprintf("0.0.0.0:%d", *port))
    wg := sync.WaitGroup{}

    wg.Add(1)
    go func() {
        server.Run()
        wg.Done()
    }()

    wg.Add(1)
    go func() {
        registry.Register()
        wg.Done()
    }()

    //stop the server after one minute
    //go func() {
    //    time.Sleep(time.Minute)
    //    server.Stop()
    //    registry.Deregister()
    //}()

    wg.Wait()
}

//go run main.go -node node1 -port 28544
//go run main.go -node node2 -port 18562
//go run main.go -node node3 -port 27772
func main() {
    flag.Parse()
    StartService()
}