Hello World Helidon

This example is a Helidon-based service that returns a “Hello World” response when invoked. The application configuration uses the default, microprofile properties file.

Before you begin

Install Verrazzano by following the installation instructions.

NOTE: The Hello World Helidon example application deployment files are contained in the Verrazzano project located at <VERRAZZANO_HOME>/examples/hello-helidon, where <VERRAZZANO_HOME> is the root of the Verrazzano project.

Deploy the Hello World Helidon application

  1. Create a namespace for the application and add a label identifying the namespace as managed by Verrazzano.

    $ kubectl create namespace hello-helidon
    $ kubectl label namespace hello-helidon verrazzano-managed=true istio-injection=enabled
    
  2. To deploy the application, apply the hello-helidon OAM resources.

    $ kubectl apply -f https://raw.githubusercontent.com/verrazzano/verrazzano/v1.0.1/examples/hello-helidon/hello-helidon-comp.yaml
    $ kubectl apply -f https://raw.githubusercontent.com/verrazzano/verrazzano/v1.0.1/examples/hello-helidon/hello-helidon-app.yaml
    
  3. Wait for the application to be ready.

    $ kubectl wait \
       --for=condition=Ready pods \
       --all \
       -n hello-helidon \
       --timeout=300s
    

Explore the application

The Hello World Helidon microservices application implements a REST API endpoint, /greet, which returns a message {"message":"Hello World!"} when invoked.

NOTE: The following instructions assume that you are using a Kubernetes environment such as OKE. Other environments or deployments may require alternative mechanisms for retrieving addresses, ports, and such.

Follow these steps to test the endpoints:

  1. Get the generated host name for the application.

    $ HOST=$(kubectl get gateway hello-helidon-hello-helidon-appconf-gw \
         -n hello-helidon \
         -o jsonpath='{.spec.servers[0].hosts[0]}')
    $ echo $HOST
    hello-helidon-appconf.hello-helidon.11.22.33.44.nip.io
    
  2. Get the EXTERNAL_IP address of the istio-ingressgateway service.

    $ ADDRESS=$(kubectl get service \
         -n istio-system istio-ingressgateway \
         -o jsonpath='{.status.loadBalancer.ingress[0].ip}')
    $ echo $ADDRESS
    11.22.33.44
    
  3. Access the application:

    • Using the command line

      $ curl -sk \
         -X GET \
         https://${HOST}/greet \
         --resolve ${HOST}:443:${ADDRESS}
      {"message":"Hello World!"}
      

      If you are using nip.io, then you do not need to include --resolve.

    • Local testing with a browser

      Temporarily, modify the /etc/hosts file (on Mac or Linux) or c:\Windows\System32\Drivers\etc\hosts file (on Windows 10), to add an entry mapping the host name to the ingress gateway’s EXTERNAL-IP address. For example:

      11.22.33.44 hello-helidon.example.com
      

      Then you can access the application in a browser at https://<host>/greet.

    • Using your own DNS name

      • Point your own DNS name to the ingress gateway’s EXTERNAL-IP address.
      • In this case, you would need to edit the hello-helidon-app.yaml file to use the appropriate value under the hosts section (such as yourhost.your.domain), before deploying the hello-helidon application.
      • Then, you can use a browser to access the application at https://<yourhost.your.domain>/greet.
  4. A variety of endpoints associated with the deployed application, are available to further explore the logs, metrics, and such.

    Accessing them may require the following:

    • Run this command to get the password that was generated for the telemetry components:

      $ kubectl get secret \
         --namespace verrazzano-system verrazzano \
         -o jsonpath={.data.password} | base64 \
         --decode; echo
      

      The associated user name is verrazzano.

    • You will have to accept the certificates associated with the endpoints.

      You can retrieve the list of available ingresses with following command:

      $ kubectl get ing -n verrazzano-system
      NAME                         CLASS    HOSTS                                                    ADDRESS          PORTS     AGE
      verrazzano-ingress           <none>   verrazzano.default.140.238.94.217.nip.io                 140.238.94.217   80, 443   7d2h
      vmi-system-es-ingest         <none>   elasticsearch.vmi.system.default.140.238.94.217.nip.io   140.238.94.217   80, 443   7d2h
      vmi-system-grafana           <none>   grafana.vmi.system.default.140.238.94.217.nip.io         140.238.94.217   80, 443   7d2h
      vmi-system-kibana            <none>   kibana.vmi.system.default.140.238.94.217.nip.io          140.238.94.217   80, 443   7d2h
      vmi-system-prometheus        <none>   prometheus.vmi.system.default.140.238.94.217.nip.io      140.238.94.217   80, 443   7d2h
      

      Using the ingress host information, some of the endpoints available are:

      Description Address Credentials
      Kibana https://[vmi-system-kibana ingress host] verrazzano/telemetry-password
      Grafana https://[vmi-system-grafana ingress host] verrazzano/telemetry-password
      Prometheus https://[vmi-system-prometheus ingress host] verrazzano/telemetry-password

Troubleshooting

  1. Verify that the application configuration, domain, and ingress trait all exist.

    $ kubectl get ApplicationConfiguration -n hello-helidon
    $ kubectl get IngressTrait -n hello-helidon
    
  2. Verify that the hello-helidon service pods are successfully created and transition to the READY state. Note that this may take a few minutes and that you may see some of the services terminate and restart.

     $ kubectl get pods -n hello-helidon
    
     NAME                                      READY   STATUS    RESTARTS   AGE
     hello-helidon-workload-676d97c7d4-wkrj2   2/2     Running   0          5m39s