Adding custom routes to the mux. Cannot add root route. ("/")

[AP0rPi7uQ9]

Hello, I have feedback on slack. I tested in my app and I think this is a bug

https://grpc-ecosystem.github.io/grpc-gateway/docs/operations/inject_router/

Follow this example, I want to add some routes of my own.

err := mux.HandlePath("GET", "/abc", xxxx)
fmt.Println(err)

This is normal. err == nil, I can successfully access through the browser www.my-url.com/abc

But!!!!!!

err := mux.HandlePath("GET", "/", xxxx)
fmt.Println(err)

This is abnormal. I cannot access through www.my-url.com/, and the err return

parsing path pattern: segment neither wildcards, literal or variable: expected "{" but got "\x00": /

[AP0rPi7uQ9]

This is an example. Edit by https://grpc-ecosystem.github.io/grpc-gateway/docs/operations/inject_router/.

This example will panic. and show error message.

main.go:

package main

import (
	"context"
	"net/http"
	"testgw/helloworld"

	"github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
)

func main() {
	ctx := context.TODO()
	mux := runtime.NewServeMux()
	// Register generated routes to mux
	err := helloworld.RegisterGreeterHandlerServer(ctx, mux, &GreeterServer{})
	if err != nil {
		panic(err)
	}
	// Register custom route for  GET /hello/{name}
	// This route is OK!
	err = mux.HandlePath("GET", "/hello/{name}", func(w http.ResponseWriter, r *http.Request, pathParams map[string]string) {
		w.Write([]byte("hello " + pathParams["name"]))
	})
	if err != nil {
		panic(err)
	}
	// This route is OK!
	err = mux.HandlePath("GET", "/test/{name}", func(w http.ResponseWriter, r *http.Request, pathParams map[string]string) {
		w.Write([]byte("test with name " + pathParams["name"]))
	})
	if err != nil {
		panic(err)
	}
	// This route is OK!
	err = mux.HandlePath("GET", "/test", func(w http.ResponseWriter, r *http.Request, pathParams map[string]string) {
		w.Write([]byte("this is test " + pathParams["name"]))
	})
	if err != nil {
		panic(err)
	}
	// This route will be PANIC
	// Return: panic: parsing path pattern: segment neither wildcards, literal or variable: expected "{" but got "\x00": /
	err = mux.HandlePath("GET", "/", func(w http.ResponseWriter, r *http.Request, pathParams map[string]string) {
		w.Write([]byte("this is homepage"))
	})
	if err != nil {
		panic(err)
	}
	http.ListenAndServe(":8080", mux)
}

// GreeterServer is the server API for Greeter service.
type GreeterServer struct {

}

// SayHello implement to say hello
func (h *GreeterServer) SayHello(ctx context.Context, req *helloworld.HelloRequest) (*helloworld.HelloReply, error) {
	return &helloworld.HelloReply{
		Message: "hello " + req.Name,
	}, nil
}

return

panic: parsing path pattern: segment neither wildcards, literal or variable: expected "{" but got "\x00": /

goroutine 1 [running]:
main.main()
        C:/Users/User/go/src/testgw/main.go:46 +0x2c4
exit status 2

How to run example:

1.mkdir testgw in GOPATH & Copy MY Example main.go code into your project
2.Copy grpc-gateway/examples/internal/helloworld/ this directory into your project
3.go mod init & go mod vendor
4.go run main.go

[johanbrandhorst]

Yeah this is easily reproducible with a test:

func TestParse(t *testing.T) {
	_, err := Parse("/")
	if err != nil {
		t.Errorf("Unexpected error: %v", err)
	}
}

Unfortunately, I'm not sure what the fix should be. You'll want to dive into https://github.com/grpc-ecosystem/grpc-gateway/blob/master/internal/httprule/parse.go#L19 to see what we should be returning in this case.