Step-by-Step Guide to Configure JMX Exporter Monitoring for a Java Service on Kubernetes with Prometheus

This article explains how to expose JVM metrics of a Java service using the JMX exporter and collect them with Prometheus in a Kubernetes (Kubesphere) environment.

Step 1: Create config.yaml

The configuration file defines the exporter port and metric collection rules, for example:

hostPort: localhost:38080 # define exporter port
username:
password:
rules:
- pattern: ".*"

Step 2: Build a Docker image

Prepare a Dockerfile that copies the compiled JAR, the config.yaml , and the jmx_prometheus_agent.jar into the image, sets the working directory, and defines the entrypoint with the necessary Java options and the java‑agent pointing to the exporter.

FROM   harbor.local.com/public/tincere:jdk8-msyh
VOLUME ["/opt"]
WORKDIR /opt
ADD ./target/*.jar    /opt/myservice.jar
ADD config.yaml      /opt/config.yaml
ADD jmx_prometheus_agent.jar /opt/jmx_prometheus_agent.jar
ENTRYPOINT ["java","-Xms512M","-Xmx512M","-Xmn384M","-Xss1M","-XX:MetaspaceSize=256M","-XX:MaxMetaspaceSize=256M","-XX:+UseParNewGC","-XX:+UseConcMarkSweepGC","-XX:CMSInitiatingOccupancyFraction=92","-XX:+UseCMSCompactAtFullCollection","-XX:CMSFullGCsBeforeCompaction=0","-XX:+CMSParallelInitialMarkEnabled","-XX:+CMSScavengeBeforeRemark","-XX:+HeapDumpOnOutOfMemoryError","-XX:HeapDumpPath=/opt","-XX:+PrintGCDetails","-XX:+PrintGCDateStamps","-Xloggc:gc.log","-Dspring.profiles.active=dev","-javaagent:/opt/jmx_prometheus_agent.jar=38080:config.yaml","-jar","/opt/myservice.jar"]

Step 3: Verify metric exposure

After the service starts, you can exec into the pod and use curl to retrieve the JVM metrics endpoint.

Step 4: Create Deployment and Service

Define a Kubernetes Deployment for the Java service and expose port 38080 as jvm-port in the corresponding Service.

Step 5: Define a ServiceMonitor

Create a ServiceMonitor resource in the same namespace as Prometheus so that Prometheus can scrape the metrics:

apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  labels:
    k8s-app: jvm-test
  name: jvm-test
  namespace: kubesphere-monitoring-system
spec:
  endpoints:
  - path: /metrics
    port: jvm-port
    scheme: http
  namespaceSelector:
    any: true
  selector:
    matchLabels:
      app: jvm-test

Step 6: Adjust Prometheus selector

Modify the Prometheus resource in the kubesphere-monitoring-system namespace to include the label selector for the newly created ServiceMonitor.

Step 7: Verify Prometheus discovery

Prometheus will automatically discover the ServiceMonitor and reload its configuration. You can port‑forward to the Prometheus UI to confirm:

kubectl -n kubesphere-monitoring-system port-forward --address=0.0.0.0 prometheus-k8s-0 39090:9090

When the UI shows the expected metrics screens (as illustrated by the screenshots), the monitoring setup is successful.

Step 8: Visualize in Grafana

Import a suitable JVM dashboard into Grafana, configure the data source to point to Prometheus, and you will see real‑time JVM performance graphs.