felipeogutierrez/grpcservice

felipeogutierrez/httptogrpc

Akka gRPC Kubernetes

This is an example of an Akka HTTP application communicating with an Akka gRPC application inside of Kubernetes. The Akka HTTP application discovers the Akka gRPC application using Akka Discovery. It uses the akka-dns mechanism which relies on the SRV records created by kubernetes. The docker images felipeogutierrez/grpcservice and felipeogutierrez/httptogrpc are available at Docker Hub. They are push automatically by Travis-CI when new code is committed to github.

Running

Create the docker images httptogrpc and grpcservice of this project and publish them locally:

sbt docker:stage
sbt docker:publishLocal
docker images

Once minikube is running and ingress enabled with:

minikube start --cpus 4 --memory 8192
minikube addons enable ingress

The two applications can be deployed using:

kubectl apply -f kubernetes/grpcservice.yml
kubectl apply -f kubernetes/httptogrpc.yml

Verify the deployments:

$ kubectl get deployments
NAME                          DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
grpcservice                   1         1         1            1           40s
httptogrpc                    1         1         1            1           40s

There are services for both:

$ kubectl get services
NAME          TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
grpcservice   ClusterIP   10.106.188.203   <none>        8080/TCP   1m
httptogrpc    ClusterIP   10.103.134.197   <none>        8080/TCP   1m

Ingress just for the HTTP app:

$ kubectl get ingress
NAME         HOSTS              ADDRESS   PORTS     AGE
httptogrpc   superservice.com             80        2m

The HTTP application periodically hits the gRPC applicaton which you can see in the logs:

[INFO] [08/15/2018 07:02:51.712] [HttpToGrpc-akka.actor.default-dispatcher-4] [akka.actor.ActorSystemImpl(HttpToGrpc)] Scheduled say hello to chris
[INFO] [08/15/2018 07:02:51.730] [HttpToGrpc-akka.actor.default-dispatcher-4] [akka.actor.ActorSystemImpl(HttpToGrpc)] Scheduled say hello response Success(HelloReply(Hello, Christopher))

And you can send a HTTP request via Ingress to the httptogrpc application:

$ curl -v --header 'Host: superservice.com' $(minikube ip)/hello/donkey
> GET /hello/donkey HTTP/1.1
> Host: superservice.com
> User-Agent: curl/7.59.0
> Accept: */*
> 
< HTTP/1.1 200 OK
< Server: nginx/1.13.12
< Date: Wed, 15 Aug 2018 07:03:56 GMT
< Content-Type: text/plain; charset=UTF-8
< Content-Length: 13
< Connection: keep-alive
< 
* Connection #0 to host 192.168.99.100 left intact
Hello, donkey%

Alternatively, you can use the port-forward to redirect the service/httptogrpc to the browser on port 8080 and access from http://127.0.0.1:8080/hello/donkey.

$ kubectl port-forward service/httptogrpc 8080
Forwarding from 127.0.0.1:8080 -> 8080
Forwarding from [::1]:8080 -> 8080

Overview of this project in action

Troubleshooting

docker image rm <IMAGE_ID>
sbt docker:stage
sbt docker:publishLocal
docker login --username=felipeogutierrez
docker images
docker push felipeogutierrez/httptogrpc:1.0
docker push felipeogutierrez/grpcservice:1.0