Sample full stack ToDo application in Kotlin

Can be easily packaged into Helm chart and ready to be deployed into Kubernetes cluster.

Backend: ktor, exposed

Frontend: kotlin-react, kotlin-js-wrappers

Deployment: docker, helm, kubernetes

Build and deploy using minikube

All the commands below use FISH shell syntax on macOS

Build project and docker image

$ ./gradlew build

$ docker build -t todoapp:v0.0.3 .

(Optionally) Run inside minikube's VM

$ eval (minikube docker-env)

$ docker run -m512M --cpus 2 -it -p 9090:9090 --rm todoapp:v0.0.1

$ open http://(minikube ip):9090/

Install helm

$ brew install helm

$ helm init

Deploy application into Kubernetes cluster (minikube)

Use helm to install.

• Update dependencies (copy PostgreSQL chart into charts)

$ helm update dependencies helm-chart/todoapp

• Package chart into archive

$ helm package helm-chart/todoapp

• Install package into Kubernetes

$ helm install todoapp-0.0.3.tgz

• Setup port forwarding using command provided in helm install output. Something similar to:

  export SERVICE_NAME=(kubectl get service --namespace default -l "app=todoapp,release=geared-marmot" -o jsonpath="{.items[0].metadata.name}")
  echo "Visit http://127.0.0.1:8080 to use your application"
  kubectl port-forward svc/$SERVICE_NAME 8080:9090

Check if replication is working as expected

• Kill one or both pods

$ kubectl delete pod <app-pod-id>

• Check if new instance is automatically deployed

$ kubectl get pods

• Check if DB and data is still there from UI

Useful debugging commands

Get status of helm installation

$ helm status <installation-name>

List helm installations

$ helm list

Delete helm installation

$ helm delete <installation-name>

List kubernetes pods

$ kubectl get pods

Get logs from the pod

$ kubectl logs <pod>

TODOs

• Tests
• LoadBalancer in front of app pods
• Improve styling of Web UI
• Check if kotlin multiplatform project will allow for better code reuse between backend and frontend
• Minify JS in production build
• Do not used development server in production build
• Gradle build scripts to build docker image and helm package