gRPC服务健康检查（Health Checking）

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服务集成健康检查代码的方法

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：

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

这样就完成集成工作了，很简单吧？

完整代码如下，以gRPC官方的helloworld服务为例（下面的代码可以直接运行）：

package mainimport ("context""flag""fmt""log""net""google.golang.org/grpc"// pb "github.com/luduoxin/grpc-health-probe-sample/helloworld"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serverpb.RegisterGreeterServer(s, &server{})// register健康检查server// health check serverhealthCheckServer := 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客户端集成健康检查代码

需要导入以下几个关键的包：

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（下面的代码可以直接运行）：

package mainimport ("context""flag""fmt""log""time""google.golang.org/grpc""google.golang.org/grpc/credentials/insecure"// pb "github.com/luduoxin/grpc-health-probe-sample/helloworld"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())
}

使用grpc-health-probe工具进行健康检查

安装grpc-health-probe：

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
exitstatus2