How to grpcurl list for gRPC service with reflection on CloudRun?

Following this example:

gRPC in Google Cloud Run

https://github.com/grpc-ecosystem/grpc-cloud-run-example/blob/master/golang/README.md

I've deployed a gRPC service with reflection on CloudRun.

Using grpcurl for testing:
https://github.com/fullstorydev/grpcurl

grpcurl \
-proto protos/calculator.proto \
-d '{"first_operand": 2.0, "second_operand": 3.0, "operation": "ADD"}' \
${ENDPOINT}:443 \
Calculator.Calculate

GRPC Server Reflection Protocol
https://github.com/grpc/grpc/blob/master/doc/server-reflection.md

Now I want to use reflection following these instructions.

--- a/examples/helloworld/greeter_server/main.go
+++ b/examples/helloworld/greeter_server/main.go
@@ -40,6 +40,7 @@ import (
        "google.golang.org/grpc"
        pb "google.golang.org/grpc/examples/helloworld/helloworld"
+       "google.golang.org/grpc/reflection"
 )

 const (
@@ -61,6 +62,8 @@ func main() {
        }
        s := grpc.NewServer()
        pb.RegisterGreeterService(s, &pb.GreeterService{SayHello: sayHello})
+       // Register reflection service on gRPC server.
+       reflection.Register(s)
        if err := s.Serve(lis); err != nil {
                log.Fatalf("failed to serve: %v", err)
        }

https://github.com/grpc/grpc-go/blob/master/Documentation/server-reflection-tutorial.md#enable-server-reflection

what you tried:

a local test. Please note:
grpcurl -plaintext means not TLS. Ommiting -plaintext means TLS.

what worked:

############################
# local testing
############################
request list:
grpcurl -plaintext localhost:8080 list

result:
Calculator
grpc.reflection.v1alpha.ServerReflection

request ADD function:
grpcurl -plaintext \
    -d '{"first_operand": 2.0, "second_operand": 3.0, "operation": "ADD"}' \
    localhost:8080 \
    Calculator.Calculate

result:
{
  "result": 5
}
############################

what you tried:
a GCP CloudRun test. Please note:
grpcurl -plaintext means not TLS. Ommiting -plaintext means TLS.

what worked:

request:
grpcurl \
    -proto protos/calculator.proto \
    -d '{"first_operand": 2.0, "second_operand": 3.0, "operation": "ADD"}' \
    ${ENDPOINT}:443 \
    Calculator.Calculate

result:
{
  "result": 5
}

what didn’t work:
I want to use reflection so omitted:

-proto protos/calculator.proto \

I want to use TLS so omitted:

-plaintext

request:

grpcurl \
    -d '{"first_operand": 2.0, "second_operand": 3.0, "operation": "ADD"}' \
    ${ENDPOINT}:443 \
    Calculator.Calculate

response:

timeout

Bottom line. The local test shows reflection is working fine.
It cannot work when deployed to CloudRun.

I suppose because it requires bidirectional stream:

https://github.com/grpc/grpc/blob/master/src/proto/grpc/reflection/v1alpha/reflection.proto

service ServerReflection {
  // The reflection service is structured as a bidirectional stream, ensuring
  // all related requests go to a single server.
  rpc ServerReflectionInfo(stream ServerReflectionRequest)
      returns (stream ServerReflectionResponse);
}

gRPC Reflection requires bidirectional streaming, so make sure to check the Enable HTTP/2 option (--use-http2) while deploying. That will enable bi-di streaming.

Also make sure to use the :443 port and authenticate to the server if needed by adding Authentication metadata (see Service-to-Service authentication documentation).