Is it possible to route multiple GRPC services with Kong Ingress Controller?

Kubernetes
1

I have read following guidelines for GRPC service routing:

But I can’t find any documentation on how to route multiple GRPC services. Is it possible to do so?

2

RPCs are called via the format “[host]/[service]/[method]” so you can enable service routing by setting the ingress “path” prefix for each of your gRPC services to the fully-qualified service name (e.g. path: “/hello.HelloService/” in the case of the second linked example).

3

I changed my ingress to the following:

  paths:
  - backend:
      serviceName: grpcbin
      servicePort: 9001
    path: /hello.HelloService/

But I am unable to call it with grpcurl. I tried calling the service with the following command:

  1. grpcurl -v -d ‘{“greeting”: “Kong Hello world!”}’ -insecure $url:443 hello.HelloService.SayHello

Error invoking method "hello.HelloService.SayHello": failed to query for service descriptor "hello.HelloService": rpc error: code = Internal desc = transport: received the unexpected content-type "application/json; charset=utf-8"

  1. grpcurl -v -d ‘{“greeting”: “Kong Hello world!”}’ -insecure $url/hello.HelloService:443 hello.HelloService.SayHello

Failed to dial target host ".../hello.HelloService:443": dial tcp: lookup .../hello.HelloService: no such host

  1. grpcurl -v -d ‘{“greeting”: “Kong Hello world!”}’ -insecure $url/hello.HelloService:443 SayHello

Failed to dial target host ".../hello.HelloService:443": dial tcp: lookup .../hello.HelloService: no such host

I also tried removing the ‘/’ at the end of the path (i.e. path: /hello.HelloService) but the result is still the same

4

@freesnow The first command should be correct. I think the issue is that grpcurl is trying to call the grpc reflection API but there is no mapping. Can you try also adding another path mapping to your ingress:

 - backend:
      serviceName: grpcbin
      servicePort: 9001
   path: /grpc.reflection.v1alpha.ServerReflection/
5

Thanks. I am able to call the GRPC service after adding the path mapping above.

Does that mean I need to disable reflection for all the applications I deploy to the cluster if I need to route multiple GRPC services? Or is there another way to route multiple GRPC services with reflection enabled?

Also, after I disabled reflection for the application, I received another error when trying to call the service:
failed to query for service descriptor "...": server does not support the reflection API

6

If your use case specifically requires the reflection API for clients e.g. grpcurl then you could alternatively provide the client with the proto files via the -import-path option so it knows how to convert JSON -> protobuf. However, I think the more typical use cases involves using the generated gRPC client stubs to communicate directly via protobuf.

7

Thanks so much for the help! I am able to set up multiple GRPC services and use grpcurl to call them.

8

Hi Freesnow,
Can you please share the solution with me ?
Or the ingress file with the two different paths (for two differents grpc services)

Thanks!

10

Here’s the ingress (the second service is demo.grpc.api.v1.Demo):

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  annotations:
    configuration.konghq.com/protocols: grpc,grpcs
  name: "grpc-ingress"
  namespace: default
spec:
  rules:
    - http:
        paths:
          - path: /demo.grpc.api.v1.Demo/
            backend:
              serviceName: grpc-demo-http
              servicePort: 9090
          - path: /
            backend:
              serviceName: /hello.HelloService/
              servicePort: 9001

To call the two services with grpcurl:

  • grpcurl -insecure -proto helloDemo.proto $url:443 demo.grpc.api.v1.Demo/SayHello
  • grpcurl -insecure -d ‘{“greeting”: “Kong Hello world!”}’ -proto hello.proto $url:443 hello.HelloService.SayHello
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