Native image containers with Rockcraft plugins

In this series, I have shown how Rockcraft’s Maven and Gradle plugins make the task of producing development-time container images of your application, effortless and iteration-friendly.

The need to run a Java application within a bare-minimal runtime comes from the cloud-native and edge-computing worlds, where optimizing away unwanted dependencies to reduce the application’s memory footprint is a common effort. In that context, the Rockcraft plugins let us create custom application runtime images for non-modular and modular Java applications.

There is another problem that afflicts all kinds of Java applications. By virtue of the platform-independent design of the Java platform, applications often suffer from a slow/delayed startup. There is a category of modern Java applications, especially from the cloud-native world, with sub-second startup-time requirements, where this problem becomes critical.

GraalVM Native Image offers a promising solution to the slow-startup problem. GraalVM compiles an application into a platform-native executable binary, enabling application startup right at launch. With compile-time class loading, ahead-of-time compilation of code and minimal-to-no garbage collection, GraalVM native image suits short-lived Java applications very well.

Native image containers with the Rockcraft Maven/Gradle plugins

For your Maven and Gradle based applications, the Rockcraft plugins let you create container images packaging the self-sufficient native-image binary produced by GraalVM. The native image compilation happens on the host.

If you don’t have the pre-requisite setup for Rockcraft, please follow instructions here.

Step 1: Installing GraalVM Community Edition for JDK

For Ubuntu versions 24.04 and above, GraalVM Community Edition is available as a snap package. For the purpose of this demo exercise, we need a GraalVM installation.

snap install graalvm-jdk --channel=v21

This command installs a GraalVM JDK at /snap/graalvm-jdk/current/graalvm-ce.

Step 2: Clone your project

Let’s use the spring-petclinic project for this demo.

git clone https://github.com/spring-projects/spring-petclinic && \
cd spring-petclinic

Step 3: Configure the native compilation plugin

For Maven-based projects please add the following build plugin. The spring-petclinic project has this build plugin added.

<plugin>
    <groupId>org.graalvm.buildtools</groupId>
    <artifactId>native-maven-plugin</artifactId>
</plugin>

For a Gradle-based project add this plugin. The spring-petclinic project this plugin added.

plugin {
  ...
  id 'org.graalvm.buildtools.native' version '0.10.6'
}

Step 4: Configure the Rockcraft plugin

Make sure the Rockcraft Maven plugin is also added to the pom.xml in your Maven project.

            <plugin>
                <groupId>io.github.rockcrafters</groupId>
                <artifactId>rockcraft-maven-plugin</artifactId>
                <version>1.2.1</version>
                <executions>
                    <execution>
                        <configuration>
                            <createService>false</createService>
                        </configuration>
                        <goals>
                            <goal>create-rock</goal>
                            <goal>build-rock</goal>
                            <goal>push-rock</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>

For your Gradle project, make sure the Rockcraft plugin is configured after the GraalVM plugin.

plugin {
  ...
  id 'org.graalvm.buildtools.native' version '0.10.6'
  id 'io.github.rockcrafters.rockcraft' version '1.2.1'
}

Step 5: Running maven/gradle

The GraalVM plugins will need the location of a GraalVM installation in your environment. Use the GRAALVM_HOME environment variable to point to the installation we did in step 1.

export GRAALVM_HOME=/snap/graalvm-jdk/current/graalvm-ce

For Maven projects, run this command:

mvn -Pnative native:compile -DskipTests install

The -Pnative native:compile options trigger the native image compilation using the GraalVM installation pointed to by GRAALVM_HOME.

For Gradle-based projects run the following command using the packaged gradlew wrapper.

./gradlew nativeCompile push-rock -i

Step 6: Run the application native image

The newly pushed docker image can now be located

$ docker image ls
REPOSITORY            TAG              IMAGE ID       CREATED                 SIZE
petclinic             3.5.0-SNAPSHOT   4e46eb04bc44   About a minute ago      336MB
petclinic             latest           4e46eb04bc44   About a minute ago      336MB

Notice the bloated size! The space-time trade-off is obvious.

Now, let’s locate the native executable in this image and run it.

$ docker run petclinic exec pebble ls /*petclinic*
spring-petclinic

$ docker --network=host run petclinic exec /spring-petclinic


              |\      _,,,--,,_
             /,`.-'`'   ._  \-;;,_
  _______ __|,4-  ) )_   .;.(__`'-'__     ___ __    _ ___ _______
 |       | '---''(_/._)-'(_\_)   |   |   |   |  |  | |   |       |
 |    _  |    ___|_     _|       |   |   |   |   |_| |   |       | __ _ _
 |   |_| |   |___  |   | |       |   |   |   |       |   |       | \ \ \ \
 |    ___|    ___| |   | |      _|   |___|   |  _    |   |      _|  \ \ \ \
 |   |   |   |___  |   | |     |_|       |   | | |   |   |     |_    ) ) ) )
 |___|   |_______| |___| |_______|_______|___|_|  |__|___|_______|  / / / /
 ==================================================================/_/_/_/

:: Built with Spring Boot :: 3.5.0
...
...
2025-08-29T15:40:36.664Z  INFO 18 --- [           main] o.s.s.petclinic.PetClinicApplication : 
Started PetClinicApplication in 0.229 seconds (process running for 0.233)

The application comes up in ~0.23 seconds and is reachable at http://localhost:8080.

Thanks for reading! Below are the screen-casts for the Maven and Gradle workflows.