文章目录
- 拦截器
- 服务端拦截器
- 一元拦截器
- 流拦截器
- 客户端拦截器
- 一元拦截器
- 流拦截`
- 多个拦截器
- 代码仓库
拦截器
gRPC拦截器（interceptor）是一种函数，它可以在gRPC调用之前和之后执行一些逻辑，例如认证、授权、日志记录、监控和统计等。拦截器函数是gRPC中非常重要的概念，它允许我们在服务端和客户端添加自定义逻辑，以满足业务需求和运维需求。
在gRPC中，拦截器函数通常通过实现grpc.UnaryServerInterceptor和grpc.StreamServerInterceptor接口来定义。UnaryServerInterceptor用于拦截一元RPC请求，而StreamServerInterceptor用于拦截流式RPC请求。在客户端中，我们可以使用grpc.UnaryClientInterceptor和grpc.StreamClientInterceptor来拦截gRPC调用。
在gRPC中，拦截器函数可以被链接起来，形成一个拦截器链。在这个拦截器链中，每个拦截器函数都可以处理请求并将其转发给下一个拦截器函数，或者直接返回响应。因此，我们可以在拦截器函数中编写不同的逻辑，例如实现认证、授权、监控和统计等。
以下是一些常见的gRPC拦截器：
- 认证和授权拦截器：用于对gRPC调用进行身份验证和权限控制，例如检查token、验证用户名和密码、检查访问控制列表等；
- 日志记录拦截器：用于记录gRPC调用的日志，例如记录请求的方法、参数、响应状态等；
- 监控和统计拦截器：用于监控gRPC调用的性能和吞吐量，例如记录调用次数、响应时间、错误率等；
- 缓存拦截器：用于在服务端或客户端缓存一些数据，例如缓存计算结果、缓存数据库查询结果等。
服务端拦截器
一元拦截器
package mainimport ("context""flag""log""time""google.golang.org/grpc""google.golang.org/grpc/credentials/insecure"pb "mygrpc/proto/hello" // 引入编译生成的包
)const (defaultName = "world"
)var (addr = flag.String("addr", "localhost:50051", "the address to connect to")name = flag.String("name", defaultName, "Name to greet")
)func main() {flag.Parse()// 与服务建立连接.conn, err := grpc.Dial(*addr, grpc.WithTransportCredentials(insecure.NewCredentials()))if err != nil {log.Fatalf("did not connect: %v", err)}defer conn.Close()// 创建指定服务的客户端c := pb.NewGreeterClient(conn)// 连接服务器并打印出其响应。ctx, cancel := context.WithTimeout(context.Background(), time.Second)defer cancel()// 调用指定方法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())
}
结果
2023/12/07 14:52:55 ======= [Server Interceptor] /hello.Greeter/SayHello
2023/12/07 14:52:55 Pre Proc Message : name:"world"
2023/12/07 14:52:55 Received: world
2023/12/07 14:52:55 Post Proc Message : message:"Hello world"流拦截器
流式拦截器需要对grpc.ServerStream进行包装，重新实现RecvMsg和SendMsg方法。
func (s *server) SearchOrders(req *pb.HelloRequest, stream pb.Greeter_SearchOrdersServer) error {log.Printf("Recved %v", req.GetName())// 具体返回多少个response根据业务逻辑调整for i := 0; i < 10; i++ {// 通过 send 方法不断推送数据err := stream.Send(&pb.HelloReply{})if err != nil {log.Fatalf("Send error:%v", err)return err}}return nil
}type wrappedStream struct {// 包装器流grpc.ServerStream
}
// 接受信息拦截器
func (w *wrappedStream) RecvMsg(m interface{}) error {log.Printf("====== [Server Stream Interceptor Wrapper] Receive a message (Type: %T) at %s", m, time.Now().Format(time.RFC3339))return w.ServerStream.RecvMsg(m)
}
// 发送消息拦截器
func (w *wrappedStream) SendMsg(m interface{}) error {log.Printf("====== [Server Stream Interceptor Wrapper] Send a message (Type: %T) at %v", m, time.Now().Format(time.RFC3339))return w.ServerStream.SendMsg(m)
}func newWrappedStream(s grpc.ServerStream) grpc.ServerStream {return &wrappedStream{s}
}func orderServerStreamInterceptor(srv interface{}, ss grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {// 前置处理log.Println("====== [Server Stream Interceptor] ", info.FullMethod)// 包装器流调用 流RPCerr := handler(srv, newWrappedStream(ss))if err != nil {log.Printf("RPC failed with error %v", err)}return err
}
func main() {flag.Parse()lis, err := net.Listen("tcp", fmt.Sprintf(":%d", *port))if err != nil {log.Fatalf("failed to listen: %v", err)}// 开启rpcs := grpc.NewServer(grpc.StreamInterceptor(orderServerStreamInterceptor))// 注册服务pb.RegisterGreeterServer(s, &server{})log.Printf("service listening at %v", lis.Addr())if err := s.Serve(lis); err != nil {log.Fatalf("failed to serve: %v", err)}
}结果
GOROOT=D:\software\Go #gosetup
GOPATH=D:\software\golibrary #gosetup
D:\software\Go\bin\go.exe build -o C:\Users\29071\AppData\Local\JetBrains\GoLand2023.3\tmp\GoLand\___go_build_mygrpc_service_steamInterceptorservice.exe mygrpc/service/steamInterceptorservice #gosetup
C:\Users\29071\AppData\Local\JetBrains\GoLand2023.3\tmp\GoLand\___go_build_mygrpc_service_steamInterceptorservice.exe
2023/12/07 15:07:48 service listening at [::]:50051
2023/12/07 15:08:07 ====== [Server Stream Interceptor] /hello.Greeter/searchOrders
2023/12/07 15:08:07 ====== [Server Stream Interceptor Wrapper] Receive a message (Type: *hello.HelloRequest) at 2023-12-07T15:08:07+08:00
2023/12/07 15:08:07 Recved 开始服务端rpc流测试
2023/12/07 15:08:07 ====== [Server Stream Interceptor Wrapper] Send a message (Type: *hello.HelloReply) at 2023-12-07T15:08:07+08:00
2023/12/07 15:08:07 ====== [Server Stream Interceptor Wrapper] Send a message (Type: *hello.HelloReply) at 2023-12-07T15:08:07+08:00
2023/12/07 15:08:07 ====== [Server Stream Interceptor Wrapper] Send a message (Type: *hello.HelloReply) at 2023-12-07T15:08:07+08:00
2023/12/07 15:08:07 ====== [Server Stream Interceptor Wrapper] Send a message (Type: *hello.HelloReply) at 2023-12-07T15:08:07+08:00
2023/12/07 15:08:07 ====== [Server Stream Interceptor Wrapper] Send a message (Type: *hello.HelloReply) at 2023-12-07T15:08:07+08:00
2023/12/07 15:08:07 ====== [Server Stream Interceptor Wrapper] Send a message (Type: *hello.HelloReply) at 2023-12-07T15:08:07+08:00
2023/12/07 15:08:07 ====== [Server Stream Interceptor Wrapper] Send a message (Type: *hello.HelloReply) at 2023-12-07T15:08:07+08:00
2023/12/07 15:08:07 ====== [Server Stream Interceptor Wrapper] Send a message (Type: *hello.HelloReply) at 2023-12-07T15:08:07+08:00
2023/12/07 15:08:07 ====== [Server Stream Interceptor Wrapper] Send a message (Type: *hello.HelloReply) at 2023-12-07T15:08:07+08:00
2023/12/07 15:08:07 ====== [Server Stream Interceptor Wrapper] Send a message (Type: *hello.HelloReply) at 2023-12-07T15:08:07+08:00
Process finished with the exit code -1073741510 (0xC000013A: interrupted by Ctrl+C)客户端拦截器
一元拦截器
func orderUnaryClientInterceptor(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {// 前置处理逻辑log.Println("Method : " + method)// 调用invoker 执行远程方法err := invoker(ctx, method, req, reply, cc, opts...)// 后置处理逻辑log.Println(reply)return err
}func main() {flag.Parse()// 与服务建立连接.conn, err := grpc.Dial(*addr, grpc.WithTransportCredentials(insecure.NewCredentials()),grpc.WithUnaryInterceptor(orderUnaryClientInterceptor)) //添加拦截器if err != nil {log.Fatalf("did not connect: %v", err)}defer conn.Close()// 创建指定服务的客户端c := pb.NewGreeterClient(conn)// 连接服务器并打印出其响应。ctx, cancel := context.WithTimeout(context.Background(), time.Second) // 设置超时时间为一秒defer cancel()// 调用指定方法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())
}
结果
2023/12/07 16:37:28 Method : /hello.Greeter/SayHello
2023/12/07 16:37:28 message:"Hello world"
2023/12/07 16:37:28 Greeting: Hello worl
流拦截`
type wrappedStream struct {grpc.ClientStream
}func (w *wrappedStream) RecvMsg(m interface{}) error {log.Printf("====== [Client Stream Interceptor] Receive a message (Type: %T) at %v", m, time.Now().Format(time.RFC3339))return w.ClientStream.RecvMsg(m)
}func (w *wrappedStream) SendMsg(m interface{}) error {log.Printf("====== [Client Stream Interceptor] Send a message (Type: %T) at %v", m, time.Now().Format(time.RFC3339))return w.ClientStream.SendMsg(m)
}func newWrappedStream(s grpc.ClientStream) grpc.ClientStream {return &wrappedStream{s}
}func clientStreamInterceptor(ctx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string, streamer grpc.Streamer, opts ...grpc.CallOption) (grpc.ClientStream, error) {// 前置处理逻辑log.Println("======= [Client Interceptor] ", method)// 调用streamer 来获取客户端流s, err := streamer(ctx, desc, cc, method, opts...)if err != nil {return nil, err}return newWrappedStream(s), nil
}func main(){// 注册拦截器到客户端流conn,err:=grpc.Dial(address,grpc.WithInsecure(),grpc.WithStreamInterceptor(clientStreamInterceptor))if err != nil {log.Fatalf("did not connect: %v", err)}defer conn.Close()c := pb.NewOrderManagementClient(conn)ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)defer cancel()// 调用客户端流RPC方法searchStream, _ := c.SearchOrders(ctx, &wrapper.StringValue{Value: "Google"})for {searchOrder, err := searchStream.Recv()if err == io.EOF {log.Print("EOF")break}if err == nil {log.Print("Search Result : ", searchOrder)}}
}
结果
2023/12/07 17:10:43 ====== [Client Stream Interceptor] Send a message (Type: *hello.HelloRequest) at 2023-12-07T17:10:43+08:00
2023/12/07 17:10:43 ====== [Client Stream Interceptor] Send a message (Type: *hello.HelloRequest) at 2023-12-07T17:10:43+08:00
2023/12/07 17:10:43 客户端流传输结束
多个拦截器
在grpc中默认的拦截器不可以传多个，因为在源码中，存在一些问题
func chainUnaryClientInterceptors(cc *ClientConn) {interceptors := cc.dopts.chainUnaryIntsif cc.dopts.unaryInt != nil {interceptors = append([]UnaryClientInterceptor{cc.dopts.unaryInt}, interceptors...)}var chainedInt UnaryClientInterceptorif len(interceptors) == 0 {chainedInt = nil} else if len(interceptors) == 1 {chainedInt = interceptors[0]} else {chainedInt = func(ctx context.Context, method string, req, reply interface{}, cc *ClientConn, invoker UnaryInvoker, opts ...CallOption) error {return interceptors[0](ctx, method, req, reply, cc, getChainUnaryInvoker(interceptors, 0, invoker), opts...)}}cc.dopts.unaryInt = chainedInt
}当存在多个拦截器时，取的就是第一个拦截器。因此结论是允许传多个，但并没有用。
如果真的需要多个拦截器，可以使用 go-grpc-middleware 提供的 grpc.UnaryInterceptor 和 grpc.StreamInterceptor 链式方法。核心方法如下
func ChainUnaryClient(interceptors ...grpc.UnaryClientInterceptor) grpc.UnaryClientInterceptor {n := len(interceptors)if n > 1 {lastI := n - 1return func(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {var (chainHandler grpc.UnaryInvokercurI int)chainHandler = func(currentCtx context.Context, currentMethod string, currentReq, currentRepl interface{}, currentConn *grpc.ClientConn, currentOpts ...grpc.CallOption) error {if curI == lastI {return invoker(currentCtx, currentMethod, currentReq, currentRepl, currentConn, currentOpts...)}curI++err := interceptors[curI](currentCtx, currentMethod, currentReq, currentRepl, currentConn, chainHandler, currentOpts...)curI--return err}return interceptors[0](ctx, method, req, reply, cc, chainHandler, opts...)}}...
}
代码仓库
https://github.com/onenewcode/mygrpc.git
也可以直接下载绑定的资源。
报错：unknown error: unsupported protocol)
