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Building a Native Executable

This guide covers:

  • Compiling the application to a native executable

  • Packaging the native executable in a container

  • Debugging native executable

This guide takes as input the application developed in the Getting Started Guide.

Prerequisites

{includes}/prerequisites.adoc * A working C development environment * The code of the application developed in the Getting Started Guide.

Note
Supporting native compilation in C

What does having a working C developer environment mean?

  • On Linux, you will need GCC, and the glibc and zlib headers. Examples for common distributions:

    # dnf (rpm-based)
sudo dnf install gcc glibc-devel zlib-devel libstdc++-static
# Debian-based distributions:
sudo apt-get install build-essential libz-dev zlib1g-dev

  • XCode provides the required dependencies on macOS:

    xcode-select --install

  • On Windows, you will need to install the Visual Studio 2017 Visual C++ Build Tools

Background

Building a native executable requires using a distribution of GraalVM. There are three distributions: Oracle GraalVM Community Edition (CE), Oracle GraalVM Enterprise Edition (EE) and Mandrel. The differences between the Oracle and Mandrel distributions are as follows:

  • Mandrel is a downstream distribution of the Oracle GraalVM CE. Mandrel’s main goal is to provide a way to build native executables specifically designed to support Quarkus.

  • Mandrel releases are built from a code base derived from the upstream Oracle GraalVM CE code base, with only minor changes but some significant exclusions that are not necessary for Quarkus native apps. They support the same capabilities to build native executables as Oracle GraalVM CE, with no significant changes to functionality. Notably, they do not include support for polyglot programming. The reason for these exclusions is to provide a better level of support for the majority of Quarkus users. These exclusions also mean Mandrel offers a considerable reduction in its distribution size when compared with Oracle GraalVM CE/EE.

  • Mandrel is built slightly differently to Oracle GraalVM CE, using the standard OpenJDK project. This means that it does not profit from a few small enhancements that Oracle have added to the version of OpenJDK used to build their own GraalVM downloads. These enhancements are omitted because upstream OpenJDK does not manage them, and cannot vouch for. This is particularly important when it comes to conformance and security.

  • Mandrel is recommended for building native executables that target Linux containerized environments. This means that Mandrel users are encouraged to use containers to build their native executables. If you are building native executables for macOS, you should consider using Oracle GraalVM instead, because Mandrel does not currently target this platform. Building native executables directly on bare metal Linux or Windows is possible, with details available in the Mandrel README and Mandrel releases.

Configuring GraalVM

Tip

This step is only required for generating native executables targeting non-Linux operating systems. For generating native executables targeting Linux, you can optionally skip this section and use a builder image instead.
Tip

If you cannot install GraalVM, you can use a multi-stage Docker build to run Maven inside a Docker container that embeds GraalVM. There is an explanation of how to do this at the end of this guide.

GraalVM {graalvm-version} is required.

  1. Install GraalVM if you haven’t already. You have a few options for this:

  2. Configure the runtime environment. Set GRAALVM_HOME environment variable to the GraalVM installation directory, for example:

    export GRAALVM_HOME=$HOME/Development/mandrel/

    On macOS (not supported by Mandrel), point the variable to the Home sub-directory:

    export GRAALVM_HOME=$HOME/Development/graalvm/Contents/Home/

    On Windows, you will have to go through the Control Panel to set your environment variables.

    Tip

    Installing via scoop will do this for you.

  3. (Optional) Set the JAVA_HOME environment variable to the GraalVM installation directory.

    export JAVA_HOME=${GRAALVM_HOME}

  4. (Optional) Add the GraalVM bin directory to the path

    export PATH=${GRAALVM_HOME}/bin:$PATH
Note
Issues using GraalVM with macOS

GraalVM binaries are not (yet) notarized for macOS as reported in this GraalVM issue. This means that you may see the following error when using native-image:

“native-image” cannot be opened because the developer cannot be verified

Use the following command to recursively delete the com.apple.quarantine extended attribute on the GraalVM install directory as a workaround:

xattr -r -d com.apple.quarantine ${GRAALVM_HOME}/../..

Solution

We recommend that you follow the instructions in the next sections and package the application step by step. However, you can go right to the completed example.

Clone the Git repository: git clone {quickstarts-clone-url}, or download an {quickstarts-archive-url}[archive].

The solution is located in the getting-started directory.

Producing a native executable

The native executable for our application will contain the application code, required libraries, Java APIs, and a reduced version of a VM. The smaller VM base improves the startup time of the application and produces a minimal disk footprint.

Creating a native executable

If you have generated the application from the previous tutorial, you can find in the pom.xml the following Maven profile section:

<profiles>
    <profile>
        <id>native</id>
        <activation>
            <property>
                <name>native</name>
            </property>
        </activation>
        <properties>
            <skipITs>false</skipITs>
            <quarkus.native.enabled>true</quarkus.native.enabled>
        </properties>
    </profile>
</profiles>
Tip

You can provide custom options for the native-image command using the <quarkus.native.additional-build-args> property. Multiple options may be separated by a comma.

Another possibility is to include the quarkus.native.additional-build-args configuration property in your application.properties.

You can find more information about how to configure the native image building process in the Configuring the Native Executable section below.

We use a profile because, you will see very soon, packaging the native executable takes a few minutes. You could just pass -Dquarkus.native.enabled=true as a property on the command line, however it is better to use a profile as this allows native image tests to also be run.

Create a native executable using:

Note
Issues with packaging on Windows

The Microsoft Native Tools for Visual Studio must first be initialized before packaging. You can do this by starting the x64 Native Tools Command Prompt that was installed with the Visual Studio Build Tools. At the x64 Native Tools Command Prompt, you can navigate to your project folder and run ./mvnw package -Dnative.

Another solution is to write a script to do this for you:

cmd /c 'call "C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\VC\Auxiliary\Build\vcvars64.bat" && mvn package -Dnative'

In addition to the regular files, the build also produces target/getting-started-1.0.0-SNAPSHOT-runner. You can run it using: ./target/getting-started-1.0.0-SNAPSHOT-runner.

Note
Java preview features

Java code that relies on preview features requires special attention. To produce a native executable, this means that the --enable-preview flag needs to be passed to the underlying native image invocation. You can do so by prepending the flag with -J and passing it as additional native build argument: -Dquarkus.native.additional-build-args=-J—​enable-preview.

Build fully static native executables

Important
 Fully static native executables support is experimental.

On Linux it’s possible to package a native executable that doesn’t depend on any system shared library. There are some system requirements to be fulfilled and additional build arguments to be used along with the native-image invocation, a minimum is -Dquarkus.native.additional-build-args="--static","--libc=musl".

Compiling fully static binaries is done by statically linking musl instead of glibc and should not be used in production without rigorous testing.

Testing the native executable

Producing a native executable can lead to a few issues, and so it’s also a good idea to run some tests against the application running in the native file. The reasoning is explained in the Testing Guide.

To see the GreetingResourceIT run against the native executable, use ./mvnw verify -Dnative:

$ ./mvnw verify -Dnative
...
Finished generating 'getting-started-1.0.0-SNAPSHOT-runner' in 22.0s.
[INFO] [io.quarkus.deployment.pkg.steps.NativeImageBuildRunner] docker run --env LANG=C --rm --user 1000:1000 -v /home/zakkak/code/quarkus-quickstarts/getting-started/target/getting-started-1.0.0-SNAPSHOT-native-image-source-jar:/project:z --entrypoint /bin/bash quay.io/quarkus/ubi-quarkus-mandrel-builder-image:{mandrel-flavor} -c objcopy --strip-debug getting-started-1.0.0-SNAPSHOT-runner
[INFO] [io.quarkus.deployment.QuarkusAugmentor] Quarkus augmentation completed in 70686ms
[INFO]
[INFO] --- maven-failsafe-plugin:3.0.0-M7:integration-test (default) @ getting-started ---
[INFO] Using auto detected provider org.apache.maven.surefire.junitplatform.JUnitPlatformProvider
[INFO]
[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running org.acme.getting.started.GreetingResourceIT
Executing "/home/zakkak/code/quarkus-quickstarts/getting-started/target/getting-started-1.0.0-SNAPSHOT-runner -Dquarkus.http.port=8081 -Dquarkus.http.ssl-port=8444 -Dtest.url=http://localhost:8081 -Dquarkus.log.file.path=/home/zakkak/code/quarkus-quickstarts/getting-started/target/quarkus.log -Dquarkus.log.file.enable=true -Dquarkus.log.category."io.quarkus".level=INFO"
__  ____  __  _____   ___  __ ____  ______
 --/ __ \/ / / / _ | / _ \/ //_/ / / / __/
 -/ /_/ / /_/ / __ |/ , _/ ,< / /_/ /\ \
--\___\_\____/_/ |_/_/|_/_/|_|\____/___/
2023-05-05 10:55:52,068 INFO  [io.quarkus] (main) getting-started 1.0.0-SNAPSHOT native (powered by Quarkus 3.0.2.Final) started in 0.009s. Listening on: http://0.0.0.0:8081
2023-05-05 10:55:52,069 INFO  [io.quarkus] (main) Profile prod activated.
2023-05-05 10:55:52,069 INFO  [io.quarkus] (main) Installed features: [cdi, rest, smallrye-context-propagation, vertx]
[INFO] Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.99 s - in org.acme.getting.started.GreetingResourceIT
...
Tip

By default, Quarkus waits for 60 seconds for the native image to start before automatically failing the native tests. This duration can be changed using the quarkus.test.wait-time system property. For example, to increase the duration to 300 seconds, use: ./mvnw verify -Dnative -Dquarkus.test.wait-time=300.
Warning

This procedure was formerly accomplished using the @NativeImageTest annotation. @NativeImageTest was replaced by @QuarkusIntegrationTest which provides a superset of the testing capabilities of @NativeImageTest. More information about @QuarkusIntegrationTest can be found in the Testing Guide.

Profiles

By default, integration tests both build and run the native executable using the prod profile.

You can override the profile the executable runs with during the test using the quarkus.test.native-image-profile property. Either by adding it to application.properties or by appending it to the command line: ./mvnw verify -Dnative -Dquarkus.test.native-image-profile=test. Your %test. prefixed properties will be used at the test runtime.

You can override the profile the executable is built with and runs with using the quarkus.profile=test property, e.g. ./mvnw clean verify -Dnative -Dquarkus.profile=test. This might come handy if there are test specific resources to be processed, such as importing test data into the database.

quarkus.native.resources.includes=version.txt
%test.quarkus.native.resources.includes=version.txt,import-dev.sql
%test.quarkus.hibernate-orm.database.generation=drop-and-create
%test.quarkus.hibernate-orm.sql-load-script=import-dev.sql

With the aforementioned example in your application.properties, your Hibernate ORM managed database will be populated with test data both during the JVM mode test run and during the native mode test run. The production executable will contain only the version.txt resource, no superfluous test data.

Warning

The executable built with -Dquarkus.profile=test is not suitable for production deployment. It contains your test resources files and settings. Once the testing is done, the executable would have to be built again, using the default, prod profile.

Alternatively, if you need to specify specific properties when running tests against the native executable built using the prod profile, an option is to put those properties in file src/test/resources/application-nativeit.yaml, and refer to it from the failsafe plugin configuration using the QUARKUS_CONFIG_LOCATIONS environment variable. For instance:

<plugin>
  <artifactId>maven-failsafe-plugin</artifactId>
  <version>${surefire-plugin.version}</version>
  <executions>
    <execution>
      <goals>
        <goal>integration-test</goal>
        <goal>verify</goal>
      </goals>
      <configuration>
        <systemPropertyVariables>
          <native.image.path>${project.build.directory}/${project.build.finalName}-runner</native.image.path>
          <java.util.logging.manager>org.jboss.logmanager.LogManager</java.util.logging.manager>
          <maven.home>${maven.home}</maven.home>
        </systemPropertyVariables>
        <environmentVariables>
          <QUARKUS_CONFIG_LOCATIONS>./src/test/resources/application-nativeit.yaml</QUARKUS_CONFIG_LOCATIONS>
        </environmentVariables>
      </configuration>
    </execution>
  </executions>
</plugin>

Java preview features

Note
Java preview features

Java code that relies on preview features requires special attention. To test a native executable, this means that the --enable-preview flag needs to be passed to the Surefire plugin. Adding <argLine>--enable-preview</argLine> to its configuration section is one way to do so.

Excluding tests when running as a native executable

When running tests this way, the only things that actually run natively are your application endpoints, which you can only test via HTTP calls. Your test code does not actually run natively, so if you are testing code that does not call your HTTP endpoints, it’s probably not a good idea to run them as part of native tests.

If you share your test class between JVM and native executions like we advise above, you can mark certain tests with the @DisabledOnIntegrationTest annotation in order to skip them when testing against a native image.

Note

Using @DisabledOnIntegrationTest will also disable the test in all integration test instances, including testing the application in JVM mode, in a container image, and native image.

Testing an existing native executable

It is also possible to re-run the tests against a native executable that has already been built. To do this run ./mvnw test-compile failsafe:integration-test -Dnative. This will discover the existing native image and run the tests against it using failsafe.

If the process cannot find the native image for some reason, or you want to test a native image that is no longer in the target directory you can specify the executable with the -Dnative.image.path= system property.

Creating a Linux executable without GraalVM installed

Important
 Before going further, be sure to have a working container runtime (Docker, podman) environment. If you use Docker on Windows you should share your project’s drive at Docker Desktop file share settings and restart Docker Desktop.

Quite often one only needs to create a native Linux executable for their Quarkus application (for example in order to run in a containerized environment) and would like to avoid the trouble of installing the proper GraalVM version in order to accomplish this task (for example, in CI environments it’s common practice to install as little software as possible).

To this end, Quarkus provides a very convenient way of creating a native Linux executable by leveraging a container runtime such as Docker or podman. The easiest way of accomplishing this task is to execute:

Tip

By default, Quarkus automatically detects the container runtime. If you want to explicitly select the container runtime, you can do it with:

For Docker:

For podman:

These are regular Quarkus config properties, so if you always want to build in a container it is recommended you add these to your application.properties in order to avoid specifying them every time.
Tip

If you see the following invalid path error for your application JAR when trying to create a native executable using a container build, even though your JAR was built successfully, you’re most likely using a remote daemon for your container runtime.

Error: Invalid Path entry getting-started-1.0.0-SNAPSHOT-runner.jar
Caused by: java.nio.file.NoSuchFileException: /project/getting-started-1.0.0-SNAPSHOT-runner.jar

In this case, use the parameter -Dquarkus.native.remote-container-build=true instead of -Dquarkus.native.container-build=true.

The reason for this is that the local build driver invoked through -Dquarkus.native.container-build=true uses volume mounts to make the JAR available in the build container, but volume mounts do not work with remote daemons. The remote container build driver copies the necessary files instead of mounting them. Note that even though the remote driver also works with local daemons, the local driver should be preferred in the local case because mounting is usually more performant than copying.
Tip

Building with GraalVM instead of Mandrel requires a custom builder image parameter to be passed additionally:

Please note that the above command points to a floating tag. It is highly recommended to use the floating tag, so that your builder image remains up-to-date and secure. If you absolutely must, you may hard-code to a specific tag (see here for available tags), but be aware that you won’t get security updates that way and it’s unsupported.

Creating a container

Using the container-image extensions

By far the easiest way to create a container-image from your Quarkus application is to leverage one of the container-image extensions.

If one of those extensions is present, then creating a container image for the native executable is essentially a matter of executing a single command:

./mvnw package -Dnative -Dquarkus.native.container-build=true -Dquarkus.container-image.build=true

  • quarkus.native.container-build=true allows for creating a Linux executable without GraalVM being installed (and is only necessary if you don’t have GraalVM installed locally or your local operating system is not Linux)

Note

If you’re running a remote Docker daemon, you need to replace quarkus.native.container-build=true with quarkus.native.remote-container-build=true.

  • quarkus.container-image.build=true instructs Quarkus to create a container-image using the final application artifact (which is the native executable in this case)

See the Container Image guide for more details.

Manually using the micro base image

You can run the application in a container using the JAR produced by the Quarkus Maven Plugin. However, in this section we focus on creating a container image using the produced native executable.

Containerization Process

When using a local GraalVM installation, the native executable targets your local operating system (Linux, macOS, Windows etc). However, as a container may not use the same executable format as the one produced by your operating system, we will instruct the Maven build to produce an executable by leveraging a container runtime (as described in this section):

The produced executable will be a 64-bit Linux executable, so depending on your operating system it may no longer be runnable. However, it’s not an issue as we are going to copy it to a container. The project generation has provided a Dockerfile.native-micro in the src/main/docker directory with the following content:

FROM quay.io/quarkus/quarkus-micro-image:2.0
WORKDIR /work/
COPY target/*-runner /work/application
RUN chmod 775 /work
EXPOSE 8080
CMD ["./application", "-Dquarkus.http.host=0.0.0.0"]
Note
Quarkus Micro Image?

The Quarkus Micro Image is a small container image providing the right set of dependencies to run your native application. It is based on UBI Micro. This base image has been tailored to work perfectly in containers.

You can read more about UBI images on:

UBI images can be used without any limitations.

This page explains how to extend the quarkus-micro image when your application has specific requirements.

Then, if you didn’t delete the generated native executable, you can build the docker image with:

docker build -f src/main/docker/Dockerfile.native-micro -t quarkus-quickstart/getting-started .

And finally, run it with:

docker run -i --rm -p 8080:8080 quarkus-quickstart/getting-started

Manually using the minimal base image

The project generation has also provided a Dockerfile.native in the src/main/docker directory with the following content:

FROM registry.access.redhat.com/ubi8/ubi-minimal:8.10
WORKDIR /work/
RUN chown 1001 /work \
    && chmod "g+rwX" /work \
    && chown 1001:root /work
COPY --chown=1001:root target/*-runner /work/application

EXPOSE 8080
USER 1001

CMD ["./application", "-Dquarkus.http.host=0.0.0.0"]

The UBI minimal image is bigger than the micro one mentioned above. It contains more utilities such as the microdnf package manager.

Using a multi-stage Docker build

The previous section showed you how to build a native executable using Maven or Gradle, but it requires you to have created the native executable first. In addition, this native executable must be a Linux 64 bits executable.

You may want to build the native executable directly in a container without having a final container containing the build tools. That approach is possible with a multi-stage Docker build:

  1. The first stage builds the native executable using Maven or Gradle

  2. The second stage is a minimal image copying the produced native executable

Warning

Before building a container image from the Dockerfiles shown below, you need to update the default .dockerignore file, as it filters everything except the target directory. In order to build inside a container, you need to copy the src directory. Thus, edit your .dockerignore and remove the * line.

Such a multi-stage build can be achieved as follows:

Sample Dockerfile for building with Maven:

## Stage 1 : build with maven builder image with native capabilities
FROM quay.io/quarkus/ubi-quarkus-mandrel-builder-image:{mandrel-flavor} AS build
COPY --chown=quarkus:quarkus --chmod=0755 mvnw /code/mvnw
COPY --chown=quarkus:quarkus .mvn /code/.mvn
COPY --chown=quarkus:quarkus pom.xml /code/
USER quarkus
WORKDIR /code
RUN ./mvnw -B org.apache.maven.plugins:maven-dependency-plugin:3.1.2:go-offline
COPY src /code/src
RUN ./mvnw package -Dnative

## Stage 2 : create the docker final image
FROM quay.io/quarkus/quarkus-micro-image:2.0
WORKDIR /work/
COPY --from=build /code/target/*-runner /work/application

# set up permissions for user `1001`
RUN chmod 775 /work /work/application \
  && chown -R 1001 /work \
  && chmod -R "g+rwX" /work \
  && chown -R 1001:root /work

EXPOSE 8080
USER 1001

CMD ["./application", "-Dquarkus.http.host=0.0.0.0"]
Note
 This multi-stage Docker build copies the Maven wrapper from the host machine. The Maven wrapper (or the Gradle wrapper) is a convenient way to provide a specific version of Maven/Gradle. It avoids having to create a base image with Maven and Gradle. To provision the Maven Wrapper in your project, use: mvn wrapper:wrapper.

Save this file in src/main/docker/Dockerfile.multistage as it is not included in the getting started quickstart.

Sample Dockerfile for building with Gradle:

## Stage 1 : build with maven builder image with native capabilities
FROM quay.io/quarkus/ubi-quarkus-mandrel-builder-image:{mandrel-flavor} AS build
USER root
RUN microdnf install findutils
COPY --chown=quarkus:quarkus gradlew /code/gradlew
COPY --chown=quarkus:quarkus gradle /code/gradle
COPY --chown=quarkus:quarkus build.gradle /code/
COPY --chown=quarkus:quarkus settings.gradle /code/
COPY --chown=quarkus:quarkus gradle.properties /code/
USER quarkus
WORKDIR /code
COPY src /code/src
RUN ./gradlew build -Dquarkus.native.enabled=true

## Stage 2 : create the docker final image
FROM quay.io/quarkus/quarkus-micro-image:2.0
WORKDIR /work/
COPY --from=build /code/build/*-runner /work/application
RUN chmod 775 /work
EXPOSE 8080
CMD ["./application", "-Dquarkus.http.host=0.0.0.0"]

If you are using Gradle in your project, you can use this sample Dockerfile. Save it in src/main/docker/Dockerfile.multistage.

docker build -f src/main/docker/Dockerfile.multistage -t quarkus-quickstart/getting-started .

And, finally, run it with:

docker run -i --rm -p 8080:8080 quarkus-quickstart/getting-started
Tip

If you need SSL support in your native executable, you can easily include the necessary libraries in your Docker image.

Please see our Using SSL With Native Executables guide for more information.
Note

To use GraalVM CE instead of Mandrel, update the FROM clause to: FROM quay.io/quarkus/ubi-quarkus-graalvmce-builder-image:{graalvm-flavor} AS build.

Using a Distroless base image

Important
 Distroless image support is experimental.

If you are looking for small container images, the distroless approach reduces the size of the base layer. The idea behind distroless is the usage of a single and minimal base image containing all the requirements, and sometimes even the application itself.

Quarkus provides a distroless base image that you can use in your Dockerfile. You only need to copy your application, and you are done:

FROM quay.io/quarkus/quarkus-distroless-image:2.0
COPY target/*-runner /application

EXPOSE 8080
USER nonroot

CMD ["./application", "-Dquarkus.http.host=0.0.0.0"]

Quarkus provides the quay.io/quarkus/quarkus-distroless-image:2.0 image. It contains the required packages to run a native executable and is only 9Mb. Just add your application on top of this image, and you will get a tiny container image.

Distroless images should not be used in production without rigorous testing.

Build a container image from scratch

Important
 Scratch image support is experimental.

Building fully statically linked binaries enables the usage of a scratch image containing solely the resulting native executable.

Sample multistage Dockerfile for building an image from scratch:

## Stage 1 : build with maven builder image with native capabilities
FROM quay.io/quarkus/ubi-quarkus-graalvmce-builder-image:{graalvm-flavor} AS build
USER root
RUN microdnf install make gcc
COPY --chown=quarkus:quarkus mvnw /code/mvnw
COPY --chown=quarkus:quarkus .mvn /code/.mvn
COPY --chown=quarkus:quarkus pom.xml /code/
RUN mkdir /musl && \
    curl -L -o musl.tar.gz https://more.musl.cc/11.2.1/x86_64-linux-musl/x86_64-linux-musl-native.tgz && \
    tar -xvzf musl.tar.gz -C /musl --strip-components 1 && \
    curl -L -o zlib.tar.gz https://github.com/madler/zlib/releases/download/v1.2.13/zlib-1.2.13.tar.gz && \
    mkdir zlib && tar -xvzf zlib.tar.gz -C zlib --strip-components 1 && \
    cd zlib && ./configure --static --prefix=/musl && \
    make && make install && \
    cd .. && rm -rf zlib && rm -f zlib.tar.gz && rm -f musl.tar.gz
ENV PATH="/musl/bin:${PATH}"
USER quarkus
WORKDIR /code
RUN ./mvnw -B org.apache.maven.plugins:maven-dependency-plugin:3.1.2:go-offline
COPY src /code/src
RUN ./mvnw package -Dnative -DskipTests -Dquarkus.native.additional-build-args="--static","--libc=musl"

## Stage 2 : create the final image
FROM scratch
COPY --from=build /code/target/*-runner /application
EXPOSE 8080
ENTRYPOINT [ "/application" ]

Scratch images should not be used in production without rigorous testing.

Note
 The versions of musl and zlib may need to be updated to meet the native-image executable requirements (and UPX if you use native image compression).

Compress native images

Quarkus can compress the produced native executable using UPX. More details on UPX Compression documentation.

Separating Java and native image compilation

In certain circumstances, you may want to build the native image in a separate step. For example, in a CI/CD pipeline, you may want to have one step to generate the source that will be used for the native image generation and another step to use these sources to actually build the native executable. For this use case, you can set the additional flag quarkus.native.sources-only=true. This will execute the java compilation as if you had started native compilation (-Dnative), but stops before triggering the actual call to GraalVM’s native-image.

$ ./mvnw clean package -Dnative -Dquarkus.native.sources-only=true

After compilation has finished, you find the build artifact in target/native-sources:

$ cd target/native-sources
$ ls
getting-started-1.0.0-SNAPSHOT-runner.jar  graalvm.version  lib  native-image.args

From the output above one can see that, in addition to the produced jar file and the associated lib directory, a text file named native-image.args was created. This file holds all parameters (including the name of the JAR to compile) to pass along to GraalVM’s native-image command. A text file named graalvm.version was also created and holds the GraalVM version that should be used. If you have GraalVM installed and it matches this version, you can start the native compilation by executing:

$ cd target/native-sources
$ native-image $(cat native-image.args)
...
$ ls
native-image.args
getting-started-1.0.0-SNAPSHOT-runner
getting-started-1.0.0-SNAPSHOT-runner.build_artifacts.txt
getting-started-1.0.0-SNAPSHOT-runner.jar

The process for Gradle is analogous.

Running the build process in a container is also possible:

$ ./mvnw clean package -Dquarkus.native.enabled=true -Dquarkus.native.sources-only=true -Dquarkus.native.container-build=true

-Dquarkus.native.container-build=true will produce an additional text file named native-builder.image holding the docker image name to be used to build the native image.

cd target/native-sources
docker run \
  -it \
  --user $(id -ur):$(id -gr) \
  --rm \
  -v $(pwd):/work \# (1)
  -w /work \# (2)
  --entrypoint /bin/sh \
  $(cat native-builder.image) \# (3)
  -c "native-image $(cat native-image.args) -J-Xmx4g"# (4)

  1. Mount the host’s directory target/native-image to the container’s /work. Thus, the generated binary will also be written to this directory.

  2. Switch the working directory to /work, which we have mounted in <1>.

  3. Use the docker image from the file native-builder.image.

  4. Call native-image with the content of file native-image.args as arguments. We also supply an additional argument to limit the process’s maximum memory to 4 Gigabytes (this may vary depending on the project being built and the machine building it).

Warning

If you are running on a Windows machine, please keep in mind that the binary was created within a Linux docker container. Hence, the binary will not be executable on the host Windows machine.

A high level overview of what the various steps of a CI/CD pipeline would look is the following:

  1. Register the output of the step executing ./mvnw …​ command (i.e. directory target/native-image) as a build artifact,

  2. Require this artifact in the step executing the native-image …​ command, and

  3. Register the output of the step executing the native-image …​ command (i.e. files matching target/*runner) as build artifact.

The environment executing step 1 only needs Java and Maven (or Gradle) installed, while the environment executing step 3 only needs a GraalVM installation (including the native-image feature).

Depending on what the final desired output of the CI/CD pipeline is, the generated binary might then be used to create a container image.

Debugging native executable

Native executables can be debugged using tools such as gdb. For this to be possible native executables need to be generated with debug symbols.

Note
 Debug symbol generation is only supported on Linux. Windows support is still under development, while macOS is not supported.

To generate debug symbols, add -Dquarkus.native.debug.enabled=true flag when generating the native executable. You will find the debug symbols for the native executable in a .debug file next to the native executable.

Note

The generation of the .debug file depends on objcopy. As a result, when using a local GraalVM installation on common Linux distributions you will need to install the binutils package:

# dnf (rpm-based)
sudo dnf install binutils
# Debian-based distributions
sudo apt-get install binutils

When objcopy is not available debug symbols are embedded in the executable.

Aside from debug symbols, setting -Dquarkus.native.debug.enabled=true flag generates a cache of source files for any JDK runtime classes, GraalVM classes and application classes resolved during native executable generation. This source cache is useful for native debugging tools, to establish the link between the symbols and matching source code. It provides a convenient way of making just the necessary sources available to the debugger/IDE when debugging a native executable.

Sources for third party jar dependencies, including Quarkus source code, are not added to the source cache by default. To include those, make sure you invoke mvn dependency:sources first. This step is required in order to pull the sources for these dependencies, and get them included in the source cache.

The source cache is located in the target/sources folder.

Tip

If running gdb from a different directory than target, then the sources can be loaded by running:

directory path/to/target

in the gdb prompt.

Or start gdb with:

gdb -ex 'directory path/to/target' path/to/target/{project.name}-{project.version}-runner

e.g.,

gdb -ex 'directory ./target' ./target/getting-started-1.0.0-SNAPSHOT-runner

For a more detailed guide about debugging native images please refer to the Native Reference Guide.

Using Monitoring Options

Monitoring options such as JDK flight recorder, jvmstat, heap dumps, NMT (starting with Mandrel 24.1 for JDK 23), and remote JMX can be added to the native executable build. Simply supply a comma separated list of the monitoring options you wish to include at build time.

-Dquarkus.native.monitoring=<comma separated list of options>
Monitoring Option Description Availability As Of

jfr

Include JDK Flight Recorder support

GraalVM CE 21.3 Mandrel 21.3

jvmstat

Adds jvmstat support

GraalVM 22.3, GraalVM CE 17.0.7 Mandrel 22.3 Mandrel 23.0 (17.0.7)

heapdump

Adds support for generating heap dumps

GraalVM 22.3, GraalVM CE 17.0.7 Mandrel 22.3 Mandrel 23.0 (17.0.7)

jmxclient

Adds support for connections to JMX servers.

GraalVM for JDK 17/20 Mandrel 23.0

jmxserver

Adds support for accepting connections from JMX clients.

GraalVM for JDK 17/20 Mandrel 23.0 (17.0.7)

nmt

Adds support for native memory tracking.

GraalVM for JDK 23 Mandrel 24.1

all

Adds all monitoring options.

GraalVM 22.3, GraalVM CE 17.0.7 Mandrel 22.3 Mandrel 23.0 (17.0.7)

Please see the Quarkus Native Reference Guide for more detailed information on these monitoring options.

Configuring the Native Executable

There are a lot of different configuration options that can affect how the native executable is generated. These are provided in application.properties the same as any other config property.

The properties are shown below:

What’s next?

This guide covered the creation of a native (binary) executable for your application. It provides an application exhibiting a swift startup time and consuming less memory. However, there is much more.

We recommend continuing the journey with the deployment to Kubernetes and OpenShift.