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/v1.0.4/examples/hello-helidon/hello-helidon-comp.yaml
   $ kubectl apply -f https://raw.githubusercontent.com/verrazzano/verrazzano/v1.0.4/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