Docker Container JVM Monitoring

This troubleshooting guide explains container monitoring for a container JVM so you can configure JMX remote access, container port mapping, and Docker network connectivity for the Nodinite JMX Monitoring Agent.

How JMX Monitoring Works with Docker

When a JVM runs inside a Docker container, the JMX port is bound inside the container and must be exposed to the host network using Docker port mapping. The Spring Boot Gateway then connects through the Docker network to the host IP on the mapped port.

Diagram: JMX monitoring for a JVM in a Docker container, where the JMX port is mapped from the container to the host network for Spring Boot Gateway access.

Configuring JMX Remote for Docker Containers

Step 1: Expose the JMX Port in Docker

Add JMX remote flags to the JVM startup command and expose the port in the Docker configuration:

java \
  -Dcom.sun.management.jmxremote=true \
  -Dcom.sun.management.jmxremote.port=5002 \
  -Dcom.sun.management.jmxremote.rmi.port=5002 \
  -Dcom.sun.management.jmxremote.authenticate=false \
  -Dcom.sun.management.jmxremote.ssl=false \
  -Djava.rmi.server.hostname=<DOCKER_HOST_IP> \
  -jar myapp.jar

Important

The -Djava.rmi.server.hostname parameter must be set to the Docker host IP address, not localhost or the container IP. This is the IP that the Spring Boot Gateway uses to connect back to the JVM. Without this setting, JMX connections from outside the container will fail.

Step 2: Map the Port in Docker Run or Compose

Docker Run:

docker run -p 5002:5002 my-java-app

Docker Compose:

services:
  boomi-atom:
    image: boomi/atom:latest
    ports:
      - "5002:5002"
    environment:
      - JAVA_OPTS=-Dcom.sun.management.jmxremote.port=5002 ...

Step 3: Configure in Nodinite JMX Agent

In the JMX Monitoring Agent Configuration:

• Address - The Docker host IP address, not the container IP
• Port - The mapped host port, 5002 in the example above
• Heap monitoring - Enable Heap Size thresholds for the target container JVM
• CPU monitoring - Enable CPU thresholds for the target container JVM

Kubernetes Considerations

For JVMs running in Kubernetes pods, JMX monitoring requires either:

• Exposing the JMX port via a Kubernetes NodePort or LoadBalancer service
• Running the Spring Boot Gateway as a sidecar container in the same pod

Note

In Kubernetes environments, pod IP addresses change on pod restarts. Use a Kubernetes Service with a stable DNS name or static NodePort to provide a consistent JMX endpoint for the Nodinite monitoring agent.

Common Docker JMX Issues

Spring Boot Gateway cannot connect to a containerized JVM

Cause: The -Djava.rmi.server.hostname value is not set or is set to localhost or the container IP.

Resolution: Set -Djava.rmi.server.hostname=<DOCKER_HOST_IP> where <DOCKER_HOST_IP> is the IP address reachable by the Spring Boot Gateway.

JMX connects successfully but heap metrics show zero

Cause: The JVM inside the container reports zero heap if the container has memory limits but the JVM is not configured to respect them.

Resolution: Add -XX:+UseContainerSupport in JDK 8u191+ and JDK 10+ to enable JVM container awareness. This allows the JVM to detect Docker memory limits and set heap accordingly.

JMX expose settings are correct but metrics still fail

Cause: The published port is not reachable from the Docker host or another Docker network segment.

Resolution: Verify the container port mapping, host firewall rules, and Docker network routing between the Spring Boot Gateway and the target container.

Next Step

Enable JMX Remote Monitoring
Costs and Licensing

Related Topics

Multi-JVM Monitoring
OS vs JVM Monitoring
JMX Troubleshooting Overview