k8s.md

Kubernetes

Simple Kubernetes manifests can be found in the k8s folder. The configuration there, as well as the instructions in this document, are designed for a local bare-metal cluster (particularly using minikube) for testing how the distributed system behaves across multiple replicas.

Configuration

There are 3 manifests in the k8s folder:

• app.yaml: The Deployment and Service for the session-queue app
• redis.yaml: Simple Redis Deployment and Service for the session-queue replicas.
• config.yaml: Environment variable configuration for session-queue with some sensible testing defaults.

Run Locally (minikube)

Make sure minikube is running on your machine with:

minikube start

The app manifest points at a local image rather than pulling from a remote registry for local testing ease. Build the image in minikube's environment with the following:

eval $(minikube docker-env)
docker build -t session-queue:latest .

Now with the image built and available, you should be able to apply all the manifests, with:

kubectl apply -f k8s

The URL of session-queue's NodePort Service can now be retrieved with minikube:

minikube service session-queue --url

You should now be able to interact with the system, using a HTTP client of your choice, with this URL. For example, with HTTPie:

http POST {url}/join
http GET {url}/status "Authorization: Bearer {token}"

You can also access logs of the replicas with:

kubectl get pods # This will list random-generated pod names
kubectl logs {pod} --follow

Production

As mentioned, the out-the-box manifests are made for local development testing. There are various changes that could/should be made for a production-ready k8s deployment, including:

• Pushing the image to a remote registry and not using imagePullPolicy: Never
• Using a Service of type LoadBalancer to expose the deployment (particularly if on a cloud environment)
• Storing the JWT secret outside of config/source control, and using something like ESO to inject it