covid-api-helidon

COVID Dashboard API Component

Build and run

With JDK17+

mvn package
java -jar target/covid-api-helidon.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/covid-api-helidon

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

Build the Docker Image

docker build -t covid-api-helidon .

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/covid-api-helidon-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/covid-api-helidon-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.

Reporting bugs

Please use the Github issue tracker for any bugs or feature suggestions:

https://github.com/UCL/covid-api-helidon/issues

Authors

• David Guzman (Github: @david-guzman)