Dependencies

• Have a Google Cloud Platform Account
• Google Cloud SDK
• kubectl (install from gcloud sdk)
• Docker
• JDK8

Kotlin

Features

• Compiles to JVM bytecode or JavaScript
• Lean Syntax
• Type inference
• Null-safety
• Extension functions
• Functional programmin support

Kubernetes (part 1)

We need to create a cluster and configure the shell for anything to work.

Create a cluster:

gcloud container clusters create demo-cluster --num-nodes=2

Configure shell to use the cluster as default

gcloud config set container/cluster demo-cluster

Docker

Build the docker image

docker build --no-cache . -t demo

Run the docker image

docker run -it --rm -p 8080:8080 demo

Tag the image with desired tags (defaults to latest)

docker tag demo eu.gcr.io/andrelin-dev/demo

Push the image to GCR

docker push eu.gcr.io/andrelin-dev/demo

List all the images in the repository

gcloud container images list --repository eu.gcr.io/andrelin-dev

List all the versions of an image

gcloud container images list-tags eu.gcr.io/andrelin-dev/demo

Kubernetes (part 2)

Deployment

Create a deployment

kubectl run demo --image=gcr.io/andrelin-dev/demo --port 8080

Expose the deployment by creating a load balancer for the deployment

kubectl expose deployment demo --type=LoadBalancer --port 80 --target-port 8080

Scale the deployment

kubectl scale deployment demo --replicas=3

Check the deployment

View the pods and their status

kubectl get pods

View the service, get information like IPs

kubectl get service

Changing the running image:

kubectl set image deployment/demo demo=eu.gcr.io/andrelin-dev/demo:v2

Rollback

kubectl set image deployment/demo demo=eu.gcr.io/andrelin-dev/demo:v1

Cleaning up

Delete the service

kubectl delete service demo

Also deallocates the load balancer The load balancer will be deleted asynchronously. Wait for that process to complete by monitoring the output of:

gcloud compute forwarding-rules list

The forwarding rule will disappear when the load balancer is deleted.

Delete the cluster

Deletes the resources used by the cluster, including virtual machines, disks, and network resources:

gcloud container clusters delete demo-cluster

Delete the project

gcloud projects delete andrelin-dev

References

1. GCP Tutorial - Run a simple app on GCPs Kubernetes Engine
2. Spring.io Tutorial - Build a Simple Spring Boot Kotlin Blog
3. Spring.io Github repo
4. Why use Kotlin?