WriteHeader is not called on 200s

[Zach-Johnson]

🐛 Bug Report

I've written a simple http middleware that logs request information, including the status code of the response. On 200 responses, the status code logged is 0. For non-200 responses, I see the correct status code being logged. It seems like WriteHeader is not called on successful responses and I think it should be.

To Reproduce

type statusRec struct {
	http.ResponseWriter
	status int
}

func (r *statusRec) WriteHeader(status int) {
	r.status = status
	r.ResponseWriter.WriteHeader(status)
}

func NewMiddleware(
	l *zap.SugaredLogger,
) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			start := time.Now()
			wrapped := &statusRec{ResponseWriter: w}

			next.ServeHTTP(wrapped, r)

			l.Infow("request",
				"method", r.Method,
				"path", r.URL.Path,
				"duration", time.Since(start),
				"status", wrapped.status,
			)
		})
	}
}

func (s *Server) GetReport(ctx context.Context, req *pb.GetReportRequest) (*pb.GetReportResponse, error) {
	// return &pb.GetReportResponse{}, status.Error(codes.Unknown, "err") // This will properly log the status code

        // This will not log anything for the status code
	return &pb.GetReportResponse{
		Echo: req,
	}, nil
}

// Attach the middleware to your runtime.Mux

Expected behavior

I expect that the request log contains a 200 for the response code

Actual Behavior

I see a zero for the status code in the request log

Your Environment

Local machine, v2.16.0 of grpc gateway, macOS

[johanbrandhorst]

Thanks for your issue. The Go HTTP handler will automatically set the header to 200 if not otherwise called. There is no need to do it explicitly.