Chapter 8. Monitoring

This section contains information about monitoring your Thorntail–based application running on OpenShift.

8.1. Accessing JVM metrics for your application on OpenShift

8.1.1. Accessing JVM metrics using Jolokia on OpenShift

Jolokia is a built-in lightweight solution for accessing JMX (Java Management Extension) metrics over HTTP on OpenShift. Jolokia allows you to access CPU, storage, and memory usage data collected by JMX over an HTTP bridge. Jolokia uses a REST interface and JSON-formatted message payloads. It is suitable for monitoring cloud applications thanks to its comparably high speed and low resource requirements.

For Java-based applications, the OpenShift Web console provides the integrated hawt.io console that collects and displays all relevant metrics output by the JVM running your application.

Prerequistes

  • the oc client authenticated
  • a Java-based application container running in a project on OpenShift
  • latest JDK 1.8.0 image

Procedure

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

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

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

    oc edit dc/MY_APP_NAME

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

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

  4. Redeploy the pod running your application. 

    oc rollout latest dc/MY_APP_NAME

    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.

Additional resources