微服务框架 go-kratos 中负载均衡使用
一、介绍
在前面这篇文章 负载均衡和它的算法介绍，讲了什么是负载均衡以及作用、算法介绍。
go-kratos 的负载均衡主要接口是 Selector，它是一个可插拔的设计。因为它设计的都是接口，只要实现了接口就实现了负载均衡。
go-kratos 在目录下提供了一个默认的 Selector 实现，default_node.go 和 default_selector.go 。
你可以自定义程序来替换这个默认实现。可以通过替换 NodeBuilder 实现节点权重计算算法，Filter 实现服务路由过滤策，Balancer 来实现负载均衡算法。
go-kratos 负载均衡结构主要组成：
在 go-kratos 中已支持 3 种负载均衡算法，分别是：
- wrr : Weighted round robin (Kratos Client内置默认算法)，权重轮询算法
- p2c : Power of two choices
- random : Random，随机算法
二、基本使用
go-kratos 负载均衡有2个使用，一个是 http ，一个是 gRPC。
在 go-kratos 文档中展示了主要代码。
> go-kratos v2.6.1
>
> go v1.20.2
示例代码在 go-kratos 的 examples 中的 Selector。
从上面例子中摘出 grpc 负载均衡例子，代码如下：
client/grpc.go
package main
import (
"context"
"log"
"time"
"github.com/go-kratos/kratos/contrib/registry/consul/v2"
"github.com/go-kratos/v2/selector/filter"
"github.com/go-kratos/v2/selector/wrr"
"github.com/go-kratos/v2/transport/grpc"
"github.com/hashicorp/consul/api"
"gitub.com/go-kratos/examples/helloworld/helloworld"
)
func main() {
consulCli, err := api.NewClient(api.DefaultConfig())
if err != nil {
panic(err)
}
r := consul.New(consulCli)
// grpc client
conn, err := grpc.DialInsecure(
context.Background(),
grpc.WithEndpoint("discovery:///helloworld"),
grpc.WithDiscovery(r), // consul作为服务发现中心
// 负载均衡 和 filter，weighted round robin算法
grpc.WithBalancerName(wrr.Name),
grpc.WithFilter(
filter.Version("1.0.0"), //静态version=1.0.0的Filter
),
)
if err != nil {
log.Fatal(err)
}
defer conn.Close()
gClient := helloworld.NewGreeterClient(conn)
for {
time.Sleep(time.Second)
CallGRPC(gClient)
}
}
func CallGRPC(client helloworld.NewGreeterClient) {
reply, err := client.SayHello(context.Background(), &helloworld.HelloRequest{Name: "go-kratos"})
if err != nil {
log.Fatal(err)
}
log.Printf("[grpc] SayHello %+v \n", reply)
}
服务端，server/grpc.go
package main
import (
"context"
"fmt"
"os"
"github.com/go-kratos/examples/helloworld/helloworld"
"github.com/go-kratos/kratos/contrib/registry/consul/v2"
"github.com/go-kratos/kratos/v2"
"github.com/go-kratos/kratos/v2/log"
"github.com/go-kratos/kratos/v2/middleware/logging"
"github.com/go-kratos/kratos/v2/middleware/recovery"
"github.com/go-kratos/kratos/v2/transport/grpc"
"github.com/hashicorp/consul/api"
)
type server struct {
helloworld.UnimplementedGreeterServer
}
func (s *server) SayHello(ctx context.Context, in *helloworld.HelloRequest) (*helloworld.HelloReply, error) {
return &helloworld.HelloReply{Message: fmt.Sprintf("welcome %+v!", in.Name)}, nil
}
func main() {
logger := log.NewStdLogger(os.Stdout)
consulClient, err := api.NewClient(api.DefaultConfig())
if err != nil {
log.NewHelper(logger).Fatal(err)
}
go runServer("1.0.0", logger, consulClient, 8000)
go runServer("1.0.0", logger, consulClient, 8010)
runServer("2.0.0", logger, consulClient, 8020)
}
func runServer(version string, logger log.Logger, client *api.Client, port int) {
logger = log.With(logger, "version", version, "port:", port)
log := log.NewHelper(logger)
grpcSrv := grpc.NewServer(
grpc.Address(fmt.Sprintf(":%d", port+1000)),
grpc.Middleware(
recovery.Recovery(),
logging.Server(logger),
),
)
s := &server{}
helloworld.RegisterGreeterServer(grpcSrv, s)
r := consul.New(client)
app := kratos.New(
kratos.Name("helloworld"),
kratos.Server(
grpcSrv,
),
kratos.Version(version),
kratos.Registrar(r),
)
if err := app.Run(); err != nil {
log.Fatal(err)
}
}
三、参考
- https://github.com/go-kratos/kratos/blob/v2.6.1/selector/default_selector.go go-kratos v2.6.1 selector 默认实现
- https://go-kratos.dev/docs/component/selector/ go-kratos 路由与负载均衡
- https://github.com/go-kratos