Packaging Red Hat build of OpenJDK 21 applications in containers

Red Hat build of OpenJDK 21

Red Hat Customer Content Services

Abstract

Red Hat build of OpenJDK is a Red Hat offering on the Red Hat Enterprise Linux platform. The Packaging Red Hat build of OpenJDK 21 applications in containers guide provides an overview of this product and explains how to package the applications in a container.

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Chapter 1. Red Hat build of OpenJDK applications in containers

Red Hat build of OpenJDK images have default startup scripts that automatically detect application JAR files and launch Java. The script’s behavior can be customized using environment variables. For more information, see /help.md in the container.

The Java applications in the /deployments directory of the OpenJDK image are run when the image loads.

Note

Containers that contain Red Hat build of OpenJDK applications are not automatically updated with security updates. Ensure that you update these images at least once every three months.

Application JAR files can be fat JARs or thin JARs.

  • Fat JARs contain all of the application’s dependencies.
  • Thin JARs reference other JARs that contain some, or all, of the application’s dependencies.

    Thin JARs are only supported if:

    • They have a flat classpath.
    • All dependencies are JARs that are in the /deployments directory.

Chapter 2. Deploying Red Hat build of OpenJDK application in containers

You can deploy Red Hat build of OpenJDK applications in containers and have them run when the container is loaded.

Procedure

  • Copy the application JAR to the /deployments directory in the image JAR file.

    For example, the following shows a brief Dockerfile that adds an application called testubi.jar to the Red Hat build of OpenJDK 21 UBI8 image:

    FROM registry.access.redhat.com/ubi8/openjdk-17
    
    COPY target/testubi.jar /deployments/testubi.jar

Chapter 3. Updating Red Hat build of OpenJDK container images

To ensure that an Red Hat build of OpenJDK container with Java applications includes the latest security updates, rebuild the container.

Procedure

  1. Pull the base Red Hat build of OpenJDK image.
  2. Deploy the Red Hat build of OpenJDK application. For more information, see Deploying Red Hat build of OpenJDK applications in containers.

    The Red Hat build of OpenJDK container with the Red Hat build of OpenJDK application is updated.

Additional resources

Revised on 2023-11-14 18:22:37 UTC

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