Additional microservice #

Supplement the Kubernetes system with an additional microservice.

  • A microservice that is used by a call center agent to create notes for a call can be used as an example. The call center agent should be able to select the customer.
  • For calling the customer microservice the hostname customer has to be used.
  • Of course, you can copy and modify one of the existing microservices.
  • Package the microservice in a Docker image and upload it into the Docker repository. This can be done by adapting the script docker-build.sh.
  • Adapt kubernetes-deploy.sh in such a manner that the microservice is deployed.
  • Adapt kubernetes-remove.sh in such a manner that the microservice is deleted.

Interactive tutorial #

https://kubernetes.io/docs/getting-started-guides/ is an interactive tutorial that shows how to use Kubernetes. It complements this chapter well. Work through the tutorial to get an impression of the Kubernetes features.

Run a rolling update #

Kubernetes supports rolling updates. A new version of a pod is rolled out in such a way that there are no interruptions to the service. See https://kubernetes.io/docs/tasks/run-application/rolling-update-replication-controller/.

Run a rolling update! To do this you need to create a new Docker image. The scripts for compiling and delivering to the Docker hub are included in the example.

Try a hosted solution #

Cloud providers such as Google or Microsoft offer Kubernetes infrastructures, see https://kubernetes.io/docs/getting-started-guides/#hosted-solutions.

Make the example work in such an environment! The scripts can be used without changes because kubectl also supports these technologies.

Test load balancing #

Test the load balancing in the example.

  • kubectl scale alters the number of pods in a replica set. kubectl scale -h indicates which options there are. For example, scale the replica set catalog.
  • kubectl get deployments shows how many pods are running in the respective deployment.
  • Use the service. For example, minikube service apache opens the web page with links to all microservices. Select the order microservice and get the orders displayed.
  • kubectl describe pods -l run=catalog displays the running pods. There you can also find the IP address of the pods in a line which starts with IP.
  • Log into the Kubernetes node with minikube ssh. To read out the metrics, you can use a command like curl 172.17.0.8:8080/metrics. You have to adapt the IP address. This way you can display the metrics of the catalog pods which Spring Boot creates. For example, the metrics contain the number of requests that have been responded with an HTTP 200 status code (OK). If you use the catalog microservice via the web page, each pod should process some of the requests and the metrics of all pods should go up.
  • Use minikube dashboard for observing the information in the dashboard.

Deploy Docker registry examples #

The example currently uses the public Docker hub. Install your own Docker registry. Save the Docker images of the example in the registry and deploy the example from this registry.

Kubernetes workshop #

At https://github.com/GoogleCloudPlatform/kubernetes-workshops you can find material for a Kubernetes workshop to further familiarize yourself with this system.

Port asynchronous examples to Kubernetes #

Port the Kafka example (see chapter 7) or the Atom example (see chapter 8) to Kubernetes.

This shows how asynchronous microservices can also run in a Kubernetes cluster. Kafka stores data, which can be difficult in a Kubernetes system. Explore how to run a Kafka cluster in a Kubernetes system in production.

Familiarize yourself with the log #

Use kubectl logs -help for familiarizing yourself with the log administration in Kubernetes.

Take a look at the logs of at least two microservices.

Checkout logs of some pods #

Use kail for displaying the logs of some pods.

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