Go集成gRCP服务健康检查

健康检查用来检测 gRPC 服务是否可以处理 rpc 请求，gRPC 官方有专门的健康检查协议，官方也根据协议实现了相关的逻辑代码，gRPC 项目可以很方便得集成。接下来就讲解一下 gRPC 项目集成健康检查代码的方法。

gRPC 服务端

首先需要定义健康检查服务的名称，因为健康检查本身也是一个 gRPC 服务，一般情况下使用 grpc.health.v1.Health 即可：

const healthCheckService = "grpc.health.v1.Health"

然后需要导入以下几个关键的包

import (
    "google.golang.org/grpc"
    "google.golang.org/grpc/health"
    healthpb "google.golang.org/grpc/health/grpc_health_v1"
)

注册健康检查服务

grpcServer := grpc.NewServer()

// 注册健康检查server
healthCheckServer := health.NewServer()
healthCheckServer.SetServingStatus(healthCheckService, healthpb.HealthCheckResponse_SERVING) 
healthpb.RegisterHealthServer(grpcServer, healthCheckServer)

以上代码可以简写为一行


grpc_health_v1.RegisterHealthServer(grpcServer, health.NewServer())

以 gRPC 官方的 helloworld 服务为例，下面的代码可以直接运行

package main

import (
  "context"
  "flag"
  "fmt"
  "log"
  "net"

  "google.golang.org/grpc"
  pb "google.golang.org/grpc/examples/helloworld/helloworld"
  "google.golang.org/grpc/health"
  healthpb "google.golang.org/grpc/health/grpc_health_v1"
)

var (
  port = flag.Int("port", 50051, "The server port")
)

const healthCheckService = "grpc.health.v1.Health"

// server is used to implement helloworld.GreeterServer.
type server struct {
  pb.UnimplementedGreeterServer
}

// SayHello implements helloworld.GreeterServer
func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
  log.Printf("Received: %v", in.GetName())
  return &pb.HelloReply{Message: "Hello " + in.GetName()}, nil
}

func main() {
  flag.Parse()
  lis, err := net.Listen("tcp", fmt.Sprintf(":%d", *port))
  if err != nil {
    log.Fatalf("failed to listen: %v", err)
  }
  s := grpc.NewServer()
  // register业务server
  pb.RegisterGreeterServer(s, &server{})
  // register健康检查server
  // health check server
  healthCheckServer := health.NewServer()
  healthCheckServer.SetServingStatus(healthCheckService, healthpb.HealthCheckResponse_SERVING)
  healthpb.RegisterHealthServer(s, healthCheckServer)

  log.Printf("server listening at %v", lis.Addr())
  if err := s.Serve(lis); err != nil {
    log.Fatalf("failed to serve: %v", err)
  }
}

gRPC 客户端

导入包

import(
    "google.golang.org/grpc"
    _ "google.golang.org/grpc/health"
)

grpc.Dial() 方法添加对应参数


conn, err := grpc.Dial(
    *addr,
    grpc.WithTransportCredentials(insecure.NewCredentials()),
    grpc.WithDefaultServiceConfig(fmt.Sprintf(`{"HealthCheckConfig": {"ServiceName": "%s"}}`, healthCheckService)),
  )

完整代码如下，以 gRPC 官方的 helloworld 为例


package main

import (
  "context"
  "flag"
  "fmt"
  "log"
  "time"

  "google.golang.org/grpc"
  "google.golang.org/grpc/credentials/insecure"
  pb "google.golang.org/grpc/examples/helloworld/helloworld"
  _ "google.golang.org/grpc/health"
)

const (
  defaultName        = "world"
  healthCheckService = "grpc.health.v1.Health"
)

var (
  addr = flag.String("addr", "localhost:50051", "the address to connect to")
  name = flag.String("name", defaultName, "Name to greet")
)

func main() {
  flag.Parse()
  // Set up a connection to the server.
  conn, err := grpc.Dial(
    *addr,
    grpc.WithTransportCredentials(insecure.NewCredentials()),
    grpc.WithDefaultServiceConfig(fmt.Sprintf(`{"HealthCheckConfig": {"ServiceName": "%s"}}`, healthCheckService)),
  )
  if err != nil {
    log.Fatalf("did not connect: %v", err)
  }
  defer conn.Close()
  c := pb.NewGreeterClient(conn)

  // Contact the server and print out its response.
  ctx, cancel := context.WithTimeout(context.Background(), time.Second)
  defer cancel()
  r, err := c.SayHello(ctx, &pb.HelloRequest{Name: *name})
  if err != nil {
    log.Fatalf("could not greet: %v", err)
  }
  log.Printf("Greeting: %s", r.GetMessage())
}

grpc-health-probe

使用 grpc-health-probe 工具进行健康检查

go install github.com/grpc-ecosystem/grpc-health-probe@latest

安装完成后，对上面的 gRPC 服务进行健康检查：

grpc-health-probe -addr=localhost:50051

如果是健康的服务，会有如下输出：

status: SERVING

如果服务挂掉了，会有如下输出：

timeout: failed to connect service "localhost:50051" within 1s

或者：

failed to connect service at "localhost:50051": context deadline exceeded
exit status