Chainguard Container for jdk

Minimal Wolfi-based Java JDK image using OpenJDK. Used for compiling Java applications.

Chainguard Containers are regularly-updated, secure-by-default container images.

Download this Container Image

For those with access, this container image is available on cgr.dev:

docker pull cgr.dev/ORGANIZATION/jdk:latest

Be sure to replace the ORGANIZATION placeholder with the name used for your organization's private repository within the Chainguard Registry.

Compatibility Notes

Like most available alternatives, Chainguard's JDK image is built directly from the OpenJDK project. The Chainguard JDK image has few-to-zero CVEs and does not run as the root user.

Getting Started

The JDK is the standard development system for a Java application. It is used for compiling and packaging Java applications, which are then run on a JRE.

Compiling a Minimal Java Application Example

This section outlines how you can build a Java application with the Chainguard JDK Image.

Start by creating a sample Java class named HelloWolfi:

cat >HelloWolfi.java <<EOL
class HelloWolfi
{
    public static void main(String args[])
    {
        System.out.println("Hello Wolfi users!");
    }
}
EOL

Then create a multistage Dockerfile, adding the Java class you just created:

cat >Dockerfile <<EOL
FROM cgr.dev/chainguard/jdk

COPY HelloWolfi.java /home/build/
RUN javac HelloWolfi.java

FROM cgr.dev/chainguard/jre

COPY --from=0 /home/build/HelloWolfi.class /app/
CMD ["HelloWolfi"]
EOL

Following that, you can build the image:

docker build -t my-java-app .

Note that this example tags the image with my-java-app. You can now run the image by referencing this tag, as in the following command:

docker run my-java-app

Hello Wolfi users!

Using the Chainguard JDK image in a Jenkins Pipeline

Using a Chainguard Image as part of a CI/CD system like Jenkins might also be a useful option. With the Jenkins Docker agent, you can define multiple steps that use different Chainguard Images. The following is an example using the Chainguard JDK image as part of a Jenkins pipeline:

pipeline {
    agent {
        docker { image 'cgr.dev/chainguard/jdk' }
    }
    stages {
        stage('Test') {
            steps {
                # Use javac, jdeps, jlink, ...
                sh 'javac -version'
            }
        }
    }
}

For a full reference on using various images in a Jenkins pipeline, please refer to the Jenkins documentation.

Using the Chainguard JDK to create a custom JRE

A less common, but powerful, use case for the JDK image is creating an optimized custom JRE for your Java application. This involves using jdeps to produce the information about the Java modules being used and subsequently using jlink to analyze your application to eliminate all module code not being used by your application. This can create a drastically smaller JRE for a particular application.

Keep in mind that a JRE produced this way is a fit-for-purpose JRE, and is not broadly usable.

For reference, here are two additional articles describing the use of jlink to create optimized application images:

• Creating your own runtime using jlink
• Creating a Custom JRE for your Java Applications

Documentation and Resources

• (Video) How to Migrate a Java Application to Chainguard Images
• (Video) Building Minimal Images for Applications with Runtimes
• (Learning Lab) Chainguard's Java Image Learning Lab
• (Blog) Building minimal and low CVE images for Java

The latest builds of Chainguard's JRE image pass the TCK for OpenJDK Java 21.0.3 and Java 22.0.1 as provided by OpenJDK Community TCK License Agreement (OCTLA) and are Java Compatibility Kit (JCK) conformant.

What are Chainguard Containers?

Chainguard Containers are minimal container images that are secure by default.

In many cases, the Chainguard Containers tagged as :latest contain only an open-source application and its runtime dependencies. These minimal container images typically do not contain a shell or package manager. Chainguard Containers are built with Wolfi, our Linux undistro designed to produce container images that meet the requirements of a more secure software supply chain.

The main features of Chainguard Containers include:

• Minimal design, without unnecessary software bloat
• Daily builds to ensure container images are up-to-date with available security patches
• High quality build-time SBOMs attesting to the provenance of all artifacts within the image
• Verifiable signatures provided by Sigstore
• Reproducible builds with Cosign and apko (read more about reproducibility)

For cases where you need container images with shells and package managers to build or debug, most Chainguard Containers come paired with a -dev variant.

Although the -dev container image variants have similar security features as their more minimal versions, they feature additional software that is typically not necessary in production environments. We recommend using multi-stage builds to leverage the -dev variants, copying application artifacts into a final minimal container that offers a reduced attack surface that won’t allow package installations or logins.

Learn More

To better understand how to work with Chainguard Containers, please visit Chainguard Academy and Chainguard Courses.

In addition to Containers, Chainguard offers VMs and Libraries. Contact Chainguard to access additional products.

Trademarks

This software listing is packaged by Chainguard. The trademarks set forth in this offering are owned by their respective companies, and use of them does not imply any affiliation, sponsorship, or endorsement by such companies.