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https://github.com/oracle-japan/helidon-handson


https://github.com/oracle-japan/helidon-handson

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README 

        
# helidon-mp



Helidon MP application that uses the dbclient API with OracleDB database.



## Build and run



With JDK21

```bash

mvn package

java -jar target/helidon-mp.jar

```



## Exercise the application



Basic:

```

curl -X GET http://localhost:8080/simple-greet

Hello World!

```



JSON:

```

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/pokemon

[{"id":1,"type":12,"name":"Bulbasaur"}, ...]



curl -X GET http://localhost:8080/type

[{"id":1,"name":"Normal"}, ...]



curl -H "Content-Type: application/json" --request POST --data '{"id":100, "type":1, "name":"Test"}' http://localhost:8080/pokemon

```



## Try health



```

curl -s -X GET http://localhost:8080/health

{"outcome":"UP",...



```



## Building a Native Image



The generation of native binaries requires an installation of GraalVM 22.1.0+.



You can build a native binary using Maven as follows:



```

mvn -Pnative-image install -DskipTests

```



The generation of the executable binary may take a few minutes to complete depending on

your hardware and operating system. When completed, the executable file will be available

under the `target` directory and be named after the artifact ID you have chosen during the

project generation phase.



## 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":...

. . .

```



### Database Setup



Start your database before running this example.



Example docker commands to start databases in temporary containers:



Oracle:

```

docker run --rm --name xe -p 1521:1521 -p 8888:8080 wnameless/oracle-xe-11g-r2

```

For details on an Oracle Docker image, see https://github.com/oracle/docker-images/tree/master/OracleDatabase/SingleInstance



## Building the Docker Image



```

docker build -t helidon-mp .

```



## Running the Docker Image



```

docker run --rm -p 8080:8080 helidon-mp: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](https://helidon.io/docs/latest/#/about/kubernetes) 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  helidon-mp                     # Get service info

kubectl port-forward service/helidon-mp 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/helidon-mp-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/helidon-mp-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.