Skip to main content


Applying the agent

Based on an existing Docker image, build an image with the WhaTap agent settings added.


This document covers only the installation of the Java agent. To apply with WhaTap Kubernetes monitoring, see the following.

  1. Create a Docker build directory.

    mkdir -p {Docker build dir}
  2. Create the whatap.conf file.

    cat >{Docker build Dir}/whatap.conf <<EOL
    #Enter the access key.
    #Enter the collection server IP.
  3. Create a Dockerfile.

    In case of building an image, you can copy the jar file to apply in the -javaagent option from the WhaTap image.

    cat >/home/silver/whatap/docker/Dockerfile <<EOL
    FROM whatap/kube_mon as build
    ## Create an actual image (Add the WhaTap image)
    ## $Image_Name (image name)
    FROM $Image_Name
    RUN mkdir -p /whatap
    COPY --from=build /data/agent/micro/whatap.agent-*.jar /whatap
    COPY ./whatap.conf /whatap/
  4. In JAVA_OPT, add the following content.

    WHATAP_JAR=ls ${WHATAP_HOME}/whatap.agent-*.jar | sort -V | tail -1
    export JAVA_OPTS="-javaagent:${WHATAP_JAR} "
  5. Build the Docker.

    cd docker
    docker build -t $Image_Name

In case of Java 17 or later, add the following options for reflection.



You can modify the Java agent file name by using the Rename function. Once the Java agent name has been modified, enter a new name in JAVA_OPTS.

Example of how to modify the Java agent name

java -cp whatap.agent-X.Y.Z.jar whatap.agent.setup.Rename -from whatap.agent-X.Y.Z.jar -to whatap.agent.jar

Viewing the heap histogram

WhaTap's Java Monitoring provides the function to view the status of heap occupancy objects in the JVM memory (sizes for each object in heap memory). In APP > Instance performance analysis, select the Heap histogram tab.

Java versions 6 to 8 support basic functions without the JVM options. However, for some Java versions, the JVM options must be applied as follows:

  • Java 9 to Java 15

    java -javaagent:{WHATAP_HOME}/whatap.agent-X.Y.Z.jar -Djdk.attach.allowAttachSelf=true -jar {application.jar}
  • Java 16 or later

    java -javaagent:{WHATAP_HOME}/whatap.agent-X.Y.Z.jar -Djdk.attach.allowAttachSelf=true --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=jdk.attach/ -jar {application.jar}

It does not support Java 5 or earlier and IBM Java.

Starting the monitoring

Once the application server is restarted after configuring all settings, the agents start collecting data. See the following.