Creating Docker images

docker build -t activator -f Dockerfile-activator .

docker build -t sources -f Dockerfile-sources .

activator is a base image for sources. It need to build only once, then evert time that sources change, rebuild sources only.

Running locally in Docker on mac:

cd akka-sample-cluster

docker run -d -it -e "THIS_IP=192.168.99.100" -e "AKKA_SAMPLE_THIS_PORT=2551" -e "AKKA_SAMPLE_SEED_IP_1=192.168.99.100" -e "AKKA_SAMPLE_SEED_PORT_1=2551" -e "AKKA_SAMPLE_SEED_IP_2=192.168.99.100" -e "AKKA_SAMPLE_SEED_PORT_2=2552" -p "2551:2551"  --name akka-sample-backend-1 sources ./bin/activator "runMain sample.cluster.factorial.FactorialBackend"

docker run -d -it -e "THIS_IP=192.168.99.100" -e "AKKA_SAMPLE_THIS_PORT=2552" -e "AKKA_SAMPLE_SEED_IP_1=192.168.99.100" -e "AKKA_SAMPLE_SEED_PORT_1=2551" -e "AKKA_SAMPLE_SEED_IP_2=192.168.99.100" -e "AKKA_SAMPLE_SEED_PORT_2=2552" -p "2552:2552"  --name akka-sample-backend-2 sources ./bin/activator "runMain sample.cluster.factorial.FactorialBackend"

docker run -d -it -e "THIS_IP=192.168.99.100" -e "AKKA_SAMPLE_SEED_IP_1=192.168.99.100" -e "AKKA_SAMPLE_SEED_PORT_1=2551" -e "AKKA_SAMPLE_SEED_IP_2=192.168.99.100" -e "AKKA_SAMPLE_SEED_PORT_2=2552" --name akka-sample-frontend sources ./bin/activator "runMain sample.cluster.factorial.FactorialFrontend"

Substitute 192.168.99.100 with IP of your Docker machine (docker-machine env).

Google Container Engine (GKE)

Pushing images to GKE: doc

In my case: docker tag sources gcr.io/test1-1384/sources gcloud docker push gcr.io/test1-1384/sources

Note: Don't forget to change image names in yaml files to what you're really pushing to GKE registry.

Creating GKE cluster: doc

Credentials for K8S dashboard

gcloud container clusters akka-cluster-3 | grep username gcloud container clusters akka-cluster-3 | grep password

Note: Don't forget to change to your cluster's name

K8S dashboard link

kubectl cluster-info

Deployments: *.yaml files in the root directory should be copied to Google Cloud shell

kubectl create -f discovery-svc.yaml

kubectl create -f backend-seed.yaml

kubectl create -f frontend.yaml

Note: the deployments are set to have replicas=0

To start up the cluster:

kubectl scale --replicas=2 deployment/cluster-backend-seed

kubectl scale --replicas=1 deployment/cluster-frontend

Seed nodes and dynamic IPs

In order to be able to join for node in Akka Cluster, it should know cluster seed nodes IPs and ports. When ports could be fixed, IPs in K8S are dynamic.

To provide dynamic discovery for seed nodes you can use etcd, ConstructR or K8S built-in headless service functionality. This project uses headless service approach. The idea of this approach is to create a headless service and set spec.clusterIP to None. Selector for this service in my case (discovery-svc.yaml in root directory) is

        name: seed-node

And associated selector in spec in backend-seed.yaml is seed-node. So when you first deploy discovery service and then backend seed nodes, all pods created from backend-seed.yaml deployment will show up as IPs associated with discovery-svc.default.svc.cluster.local domain. That's how each seed node finds all previously registered currently running seed nodes' IPs, same mechanism applies to regular non-seed nodes as well.