Helidon Example: quickstart-se

This example implements a simple REST service.

Prerequisites

Maven 3.5 or newer
Java SE 8 or newer
Docker 17 or newer to build and run docker images
Kubernetes cluster
Kubectl 1.7.4 or newer to deploy to Kubernetes

Verify prerequisites

java -version
mvn --version
docker --version
kubectl version --short

Build

mvn package

Start the application

java -jar target/quickstart-se.jar

Exercise the application

curl -X GET http://localhost:8080/greet
{"message":"Hello World!"}

curl -X GET http://localhost:8080/greet/Joe
{"message":"Hello Joe!"}

curl -X PUT -H "Content-Type: application/json" -d '{"greeting" : "Hola"}' http://localhost:8080/greet/greeting

curl -X GET http://localhost:8080/greet/Jose
{"message":"Hola Jose!"}

curl -X GET http://localhost:8080/beers
[{"id":"0001-201902","name":"Augustiner","type":"Heles","strength":5}]

Try health and metrics

curl -s -X GET http://localhost:8080/health
{"outcome":"UP",...
. . .

# Prometheus Format
curl -s -X GET http://localhost:8080/metrics
# TYPE base:gc_g1_young_generation_count gauge
. . .

# JSON Format
curl -H 'Accept: application/json' -X GET http://localhost:8080/metrics
{"base":...
. . .

Build the Docker Image

docker build -t quickstart-se target

Start the application with Docker

docker run --rm -p 8080:8080 quickstart-se:latest

Exercise the application as described above

Deploy the application to Kubernetes

kubectl cluster-info                # Verify which cluster
kubectl get pods                    # Verify connectivity to cluster
kubectl create -f target/app.yaml   # Deply application
kubectl get service quickstart-se   # Get service info

Exercise the Application on Kubernetes

Start the Kubernetes proxy server so you can connect to your service via localhost:

kubectl proxy

Next get the service’s info.

kubectl get service quickstart-se

Note the PORTs. You can now exercise the application as you did before but use the second port number (the NodePort) instead of 8080. For example:

curl -X GET http://localhost:31431/greet
curl -X GET http://localhost:31431/beers

After you’re done, cleanup.

Remove the application from Kubernetes

kubectl delete -f target/app.yaml

ldimitrov/helidon-playground