Chapter 6. Integrating with OpenShift

Procedure

1. Go to Enabling monitoring for user-defined projects and follow specific instructions on how to enable user-defined project monitoring. In summary, you will create a ConfigMap in the namespace openshift-monitoring

Procedure

1. Implement a REST API:

   <dependency>
       <groupId>io.quarkus</groupId>
       <artifactId>quarkus-resteasy</artifactId>
   </dependency>
   <dependency>
       <groupId>io.quarkus</groupId>
       <artifactId>quarkus-micrometer-registry-prometheus</artifactId>
   </dependency>

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2. Add the micrometer registry facade:

   import javax.inject.Inject;
   import javax.ws.rs.GET;
   import javax.ws.rs.Path;
   
   import io.micrometer.core.instrument.MeterRegistry;
   
   @Path("/hello")
   public class GreetingsResource {
   
       @Inject
       MeterRegistry registry;
   
       @GET
       public String sayHello() {
           registry.counter("greeting_counter").increment();
   
           return "Hello!";
       }
   }

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   This Micrometer facade creates a counter that will be incremented every time you invoke the services. The registry helps to create custom metrics or use the metrics manually. You could also annotate methods as the following:

   @GET
   @Counted(value = "greeting_counter")
   public String sayHello() {
       return "Hello!";
   }

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3. Run the application:

   mvn compile quarkus:dev

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4. Call your service:

   curl http://localhost:8080/hello

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   The service should return with Hello!

5. Browse to http://localhost:8080/q/metrics. You should see the greeting_counter with count 1.0 (the one you just completed):

   # HELP greeting_counter_total
   #TYPE greeting_counter_total counter
   greeting_counter_total 1.0

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6. Deploy your Quarkus application into OpenShift by entering the extension quarkus-openshift into your pom.xml:

   <dependency>
       <groupId>io.quarkus</groupId>
       <artifactId>quarkus-openshift</artifactId>
   </dependency>

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7. Deploy your application into a newly created project called my-project in OpenShift:

   oc new-project my-project
   
   mvn clean package -Dquarkus.kubernetes.deploy=true -Dquarkus.openshift.expose=true -Dquarkus.openshift.labels.app-with-metrics=quarkus-app

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Procedure

1. Set up your service-monitor.yaml:

   apiVersion: monitoring.coreos.com/v1
   kind: ServiceMonitor
   metadata:
     labels:
       k8s-app: prometheus-app-monitor
     name: prometheus-app-monitor
     namespace: my-project
   spec:
     endpoints:
     - interval: 30s
       targetPort: 8080
       scheme: http
     selector:
       matchLabels:
         app-with-metrics: 'quarkus-app'

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2. Apply your service-monitor.yaml:

   oc apply -f service-monitor.yaml

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   This command creates a service monitor named prometheus-app-monitor that will select applications with the label app-with-metrics: quarkus-app. This label was added during the Deploying your Quarkus application to OpenShift procedure. OpenShift calls the endpoint /metrics for all the services labeled with app-with-metrics: quarkus-app.

3. To use your service monitor:

   1. Call your greetings service: curl http://quarkus-micrometer-my-project.ocp.host/hello. This increments your greeting_counter_total counter.
   2. To see the metrics, browse to the OpenShift Console and select the Developer > Monitoring view.
   3. Select the Metrics tab.
   4. In the Custom Query field, enter greeting_counter_total.