Running our application on Kubernetes

Introduction

  • We can now deploy our code (as well as a redis instance)

Exercise

  • Deploy redis:

    kubectl create deployment redis --image=redis

  • Deploy everything else:

      for SERVICE in hasher rng webui worker; do
    kubectl create deployment $SERVICE --image=$REGISTRY/$SERVICE:$TAG
  done

Is this working?

  • After waiting for the deployment to complete, let's look at the logs!

    (Hint: use kubectl get deploy -w to watch deployment events)

Exercise

  • Look at some logs:

    kubectl logs deploy/rng
kubectl logs deploy/worker

🤔 rng is fine ... But not worker.

💡 Oh right! We forgot to expose.

Connecting containers together

  • Three deployments need to be reachable by others: hasher, redis, rng

  • worker doesn't need to be exposed

  • webui will be dealt with later

Exercise

  • Expose each deployment, specifying the right port:

    kubectl expose deployment redis --port 6379
kubectl expose deployment rng --port 80
kubectl expose deployment hasher --port 80

Is this working yet?

  • The worker has an infinite loop, that retries 10 seconds after an error

Exercise

  • Stream the worker's logs:

    kubectl logs deploy/worker --follow

    (Give it about 10 seconds to recover)

We should now see the worker, well, working happily.

Exposing services for external access

  • Now we would like to access the Web UI

  • We will expose it with a NodePort

    (just like we did for the registry)

Exercise

  • Create a NodePort service for the Web UI:

    kubectl expose deploy/webui --type=NodePort --port=80

  • Check the port that was allocated:

    kubectl get svc

Accessing the web UI

  • We can now connect to any node, on the allocated node port, to view the web UI

Exercise

Yes, this may take a little while to update. (Narrator: it was DNS.)

Alright, we're back to where we started, when we were running on a single node!