Chapter 12. Monitoring your application

Procedure

1. List the deployment configurations of the pods inside your project and select the one that corresponds to your application.

   oc get dc

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   NAME         REVISION   DESIRED   CURRENT   TRIGGERED BY
   MY_APP_NAME   2          1         1         config,image(my-app:6)
   ...

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2. Open the YAML deployment template of the pod running your application for editing.

   oc edit dc/MY_APP_NAME

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3. Add the following entry to the ports section of the template and save your changes:

   ...
   spec:
     ...
     ports:
     - containerPort: 8778
       name: jolokia
       protocol: TCP
     ...
   ...

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4. Redeploy the pod running your application.

   oc rollout latest dc/MY_APP_NAME

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   The pod is redeployed with the updated deployment configuration and exposes the port 8778.

5. Log into the OpenShift Web console.
6. In the sidebar, navigate to Applications > Pods, and click on the name of the pod running your application.
7. In the pod details screen, click Open Java Console to access the hawt.io console.

Procedure

1. Include the microprofile-metrics fraction in the pom.xml file in your application:

   pom.xml

   <dependencies>
     <dependency>
       <groupId>io.thorntail</groupId>
       <artifactId>microprofile-metrics</artifactId>
     </dependency>
   </dependencies>

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2. Annotate methods or classes with the metrics annotations, for example:

   @GET
   @Counted(name = "hello-count", absolute = true)
   @Timed(name = "hello-time", absolute = true)
   public String get() {
       return "Hello from counted and timed endpoint";
   }

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   Here, the @Counted annotation is used to keep track of how many times this method was invoked. The @Timed annotation is used to keep track of how long the invocations took.

   In this example, a JAX-RS resource method was annotated directly, but you can annotate any CDI bean in your application as well.

3. Launch your application:

   $ mvn thorntail:run

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4. Invoke the traced endpoint several times:

   $ curl http://localhost:8080/
   Hello from counted and timed endpoint

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5. Wait at least 15 seconds for the collection to happen, and see the metrics in Prometheus UI:

   1. Open the Prometheus UI at http://localhost:9090/ and type hello into the Expression box.
   2. From the suggestions, select for example application:hello_count and click Execute.
   3. In the table that is displayed, you can see how many times the resource method was invoked.
   4. Alternatively, select application:hello_time_mean_seconds to see the mean time of all the invocations.

   Note that all metrics you created are prefixed with application:. There are other metrics, automatically exposed by Thorntail as the MicroProfile Metrics specification requires. Those metrics are prefixed with base: and vendor: and expose information about the JVM in which the application runs.