The Tanzu Java Native Image Buildpack allows users to create an image containing a GraalVM native image application.

The Java Native Buildpack is a composite buildpack and each step in a build is handled by one of it's components. The following docs describe common build configurations. For a full set of configuration options and capabilities see the homepages of the component buildpacks.

About the Examples

All Java Native Image Buildpack examples will use the Paketo sample applications.

Examples assume that the root of this repository is the working directory:

git clone
cd samples

The pack CLI is used throughout the examples. pack is just one of several Cloud Native Buildpack platforms than can execute builds with the Java Native Image Buildpacks. For example, Spring Boot developers may want to explore the Spring Boot Maven Plugin or Spring Boot Gradle Plugin.

Examples assume that either the Paketo Tiny or Paketo Base builder is the default builder:

pack config default-builder paketobuildpacks/builder:tiny

All java native image example images should return {"status":"UP"} from the [actuator health endpoint][spring boot actuator endpoints].

docker run --rm --tty --publish 8080:8080 samples/java-native
curl -s http://localhost:8080/actuator/health | jq .

Supported Applications

For all native image builds, it is required that:

  • BP_NATIVE_IMAGE is set at build time.

For Spring Boot applications, it is required that:

  • The application declares a dependency on Spring Native.
  • The version of Spring Native declared by the application may require a specific version of Spring Boot. See the Spring Native release notes for supported Spring Boot versions.

Building From Source

The Java Native Image Buildpack supports the same build tools and configuration options as the Java Buildpack. The build must produce an executable jar.

After compiling and packaging, the buildpack will replace provided application source code with the exploded JAR and proceed as described in Building from an Executable Jar.

Example: Building a Native image with Maven

The following command creates an image from source with maven.

pack build samples/java-native \
  --env BP_NATIVE_IMAGE=true
  --path java/native-image/java-native-image-sample

Building from a Function

The Tanzu Java Function Buildpack provides a Spring Boot application for executing functions.


This buildpack will participate if any of the following conditions are met:

  • A buildpack configuration variable BP_FUNCTION is explicitly set.
  • A file with the name func.yaml is detected.

The buildpack will do the following if detection passed:

  • Request for a JRE to be installed
  • Contributes the function invoker to a layer marked launch with the layer's path prepended to $CLASSPATH
  • Contributes environment variables defined in func.yaml to the launch layer
  • Contributes environment variables to configure the invoker if any configuration variables are defined. (Overrides anything from func.yaml)


Environment Variable Description
$BP_FUNCTION Configure the function to load. If the function lives in the default package: . If the function lives in their own package: . . Defaults to functions.Handler

Getting Started

To get started you'll need to create a directory where your function will be defined.

From within this directory we require a few files to properly detect this as a Java function:

  • func.yaml (optional): We use this to configure the runtime environment variables. See the Knative Func CLI docs for more details.
  • pom.xml or build.gradle: These are used by the other Java buildpacks to compile your function.
  • Java package in folder src/main/java/functions: This is the default location your function will be detected. If you do choose to use another package to store your functions, you will need to define where your function is located with the BP_FUNCTION configuration for the buildpack.

Liveness / Readiness Endpoints

The Java invoker contains a readiness/liveness endpoint that can be hit at localhost:8080/actuator/health by default. For more information, please read about the Spring Boot Actuator's Kubernetes Probes.


If you want to quickly start writing your functions, take a look at the functions samples in the [application accelerators samples repo](vmware-tanzu/ application-accelerator-samples).

Building from an Executable JAR

An application developer may build an image from an exploded executable JAR. Most platforms will automatically extract provided archives.

Example: Building a Native image from an Executable JAR

The following command uses Maven directly to compile an executable JAR and then uses the pack CLI to build an image from the JAR.

cd samples/java/native-image
./mvnw package
pack build samples/java-native \
  --env BP_NATIVE_IMAGE=true
  --path java/native-image/java-native-image-sample/target/demo-0.0.1-SNAPSHOT.jar

The resulting application image will be identical to that built in the "Building a Native image with Maven" example.

About the Native Image

The GraalVM Buildpack will provide the GraalVM JDK, including the native-image utility (the Native image builder), and the Substrate VM.

The Native Image Buildpack uses native-image to compile the Java bytecode into a standalone executable. The Native Image Buildpack uses the standard tools for building native images and does not depend on Spring Native support.

Note: The native-image build is a memory intensive process and may be slow if insufficient memory is provided. From the prerequisites in the Spring Native reference docs:

"On Mac and Windows, it is recommended to increase the memory allocated to Docker to at least 8G (and potentially to add more CPUs as well) since native-image compiler is a heavy process. See this Stackoverflow answer for more details. On Linux, Docker uses by default the resources available on the host so no configuration is needed."

Inspecting the JVM Version

The exact substrate VM version that was contributed to a given image can be read from the Bill-of-Materials.

Example Inspecting the JRE Version

Given an image named samples/java-native built from one of examples above, the following command will print the exact version of the installed substrate VM.

pack inspect-image samples/java-native --bom | jq '.local[] | select(.name=="native-image-svm") | .metadata.version'

Configuring the JVM Version

The following environment variable configures the JVM version at build-time.

    • Defaults to the latest LTS version at the time of release.
    • Configures a specific JVM version.
    • Example: Given BP_JVM_VERSION=8 or BP_JVM_VERSION=8.* the buildpack will install the latest patch releases of the Java 8 JDK and JRE.

Spring Boot Applications

The Java Native Image Buildpack contains the Spring Boot Buildpack and provides the same Spring Boot features as the Java Buildpack.

Selecting a Process

The Java Native Image Buildpack will contribute a default process type that starts the application.

Example: Running the Default Process

Execute the following commands to start the default process type using a samples/java-native image built from any previous example command.

docker run  --rm --publish 8080:8080 samples/java-native
curl -s http://localhost:8080/actuator/health

Providing Additional Arguments

Additional arguments can be provided to the application using the container [CMD][oci config]. In Kubernetes set CMD using the args field on the [container][kubernetes container resource] resource.

Example: Setting the Server Port

Execute the following command passes an additional argument to application start command, setting the port to 8081.

docker run --rm --publish 8081:8081 samples/java-native --server.port=8081
curl -s http://localhost:8081/actuator/health


The following component buildpacks compose the Paketo Java Native Image Buildpack.

Buildpack Required/Optional Responsibility
Paketo GraalVM Buildpack Required Provides the GraalVM JDK and Native Image Substrate VM.
Paketo Gradle Buildpack Optional Builds Gradle-based applications from source.
Paketo Maven Buildpack Optional Builds Maven-based applications from source.
Paketo Leiningen Buildpack Optional Builds Leiningen-based applications from source.
Paketo SBT Buildpack Optional Builds SBT-based applications from source.
Paketo Executable JAR Buildpack Optional Contributes a process Type that launches an executable JAR.
Paketo Spring Boot Buildpack Optional Contributes configuration and metadata to Spring Boot applications.
Paketo Native Image Buildpack Required Creates a native image from a JVM application.
Paketo Procfile Buildpack Optional Allows the application to define or redefine process types with a Procfile
Paketo Environment Variables Buildpack Optional Contributes arbitrary user-provided environment variables to the image.
Paketo Image Labels Buildpack Optional Contributes OCI-specific and arbitrary user-provided labels to the image.

Additional Configuration

Install a Custom CA Certificate

Java Native Image buildpack users can provide their own CA certificates and have them included in the container root truststore at build-time and runtime by following the instructions outlined in the CA Certificates section of our configuration docs.

Override the Start Process Set by the Buildpack

Java Native Image buildpack users can set custom start processes for their app image by following the instructions in the Procfiles section of our configuration docs.

Set Environment Variables for App Launch Time

Java Native Image buildpack users can embed launch-time environment variables in their app image by following the documentation for the Environment Variables Buildpack.

Add Custom Labels to the App Image

Java Native Image buildpack users can add labels to their app image by following the instructions in the Applying Custom Labels section of our configuration docs.

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