diegorramos/graalvm-with-helidon

graalvm-example

Sample Helidon SE project that includes multiple REST operations.

Build and run

With JDK17+

mvn package
java -jar target/graalvm-example.jar

Exercise the application

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

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!"}

Try metrics

# 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":...
. . .

Try health

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

Building a Native Image

Make sure you have GraalVM locally installed:

$GRAALVM_HOME/bin/native-image --version

Build the native image using the native image profile:

mvn package -Pnative-image

This uses the helidon-maven-plugin to perform the native compilation using your installed copy of GraalVM. It might take a while to complete. Once it completes start the application using the native executable (no JVM!):

./target/graalvm-example

Yep, it starts fast. You can exercise the application’s endpoints as before.

Building the Docker Image

docker build -t graalvm-example .

Running the Docker Image

docker run --rm -p 8080:8080 graalvm-example:latest

Exercise the application as described above.

Run the application in Kubernetes

If you don’t have access to a Kubernetes cluster, you can install one on your desktop.

Verify connectivity to cluster

kubectl cluster-info                        # Verify which cluster
kubectl get pods                            # Verify connectivity to cluster

Deploy the application to Kubernetes

kubectl create -f app.yaml                              # Deploy application
kubectl get pods                                        # Wait for quickstart pod to be RUNNING
kubectl get service  graalvm-example                     # Get service info
kubectl port-forward service/graalvm-example 8081:8080   # Forward service port to 8081

You can now exercise the application as you did before but use the port number 8081.

After you’re done, cleanup.

kubectl delete -f app.yaml

Building a Custom Runtime Image

Build the custom runtime image using the jlink image profile:

mvn package -Pjlink-image

This uses the helidon-maven-plugin to perform the custom image generation. After the build completes it will report some statistics about the build including the reduction in image size.

The target/graalvm-example-jri directory is a self contained custom image of your application. It contains your application, its runtime dependencies and the JDK modules it depends on. You can start your application using the provide start script:

./target/graalvm-example-jri/bin/start

Class Data Sharing (CDS) Archive Also included in the custom image is a Class Data Sharing (CDS) archive that improves your application’s startup performance and in-memory footprint. You can learn more about Class Data Sharing in the JDK documentation.

The CDS archive increases your image size to get these performance optimizations. It can be of significant size (tens of MB). The size of the CDS archive is reported at the end of the build output.

If you’d rather have a smaller image size (with a slightly increased startup time) you can skip the creation of the CDS archive by executing your build like this:

mvn package -Pjlink-image -Djlink.image.addClassDataSharingArchive=false

For more information on available configuration options see the helidon-maven-plugin documentation.