Building native images with Clojure and GraalVM.

github.com/clj-easy/graalvm-clojure

Tutorial

1. Download GraalVM binaries - https://github.com/graalvm/graalvm-ce-builds/releases
2. Extract it: tar -xvzf graalvm-ce-java11-linux-amd64-21.3.0.tar.gz
3. Move it: mv graalvm-ce-java11-21.3.0/ /usr/lib/jvm/ && cd /usr/lib/jvm
4. Check current java alternatives: update-alternatives --config java
5. Add new java alternative with 100 priority: sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/graalvm-ce-java11-21.3.0/bin/java 100
6. Check java version: java --version
7. Create symlink: ln -s graalvm-ce-java11-21.3.0 graalvm
8. Add env variables to ~/.bashrc file:

export GRAALVM_HOME=/usr/lib/jvm/graalvm

9. Reload source ~/.bashrc
10. Update PATH for the current session: export PATH=$GRAALVM_HOME/bin:$PATH, didn't save it to .bashrc since it is breaking update-alternatives switching between java versions.
11. Test that gu command is available

Run: gu install native-image

Check it's available: native-image

Assuming you have Leiningen installed: sudo apt install leiningen

Run: lein new app hello-world

Build: cd hello-world && lein uberjar

Run and measure time: time java -jar target/uberjar/hello-world-0.1.0-SNAPSHOT-standalone.jar

Build:

native-image --report-unsupported-elements-at-runtime \
             --initialize-at-build-time \
             --no-server \
             -jar target/uberjar/hello-world-0.1.0-SNAPSHOT-standalone.jar \
             -H:Name=./target/hello-world

Run and measure time: time target/hello-world

GraalVM options - https://www.graalvm.org/reference-manual/native-image/Options/

1. Download and install Java 17.
2. Add new java alternative with priority 200: sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/graalvm-ce-java17-21.3.0/bin/java 200
3. Select new java: sudo update-alternatives --config java
4. Check current version: java --version
5. Update symlink: sudo ln -s graalvm-ce-java17-21.3.0 graalvm
6. Check that native-image is not installed for this java version

With Java 17 GraalVM I had to switch to root user in order to install native-image: 7. Switch to root: sudo su 8. Set env var for current session:

    export GRAALVM_HOME=/usr/lib/jvm/graalvm-ce-java17-21.3.0
    export PATH=$GRAALVM_HOME/bin:$PATH

9. Install native-image: gu install native-image
10. Exit from root: exit
11. Check that native-image available

Tip: to remove java alternative run: sudo update-alternatives --remove java /usr/lib/jvm/graalvm-ce-java11-21.3.0/bin/java

Tutorial

Tutorial 2

Docker commands:

1. List all docker images: docker images
2. Build a new docker image: docker build . -t image-name
3. Delete docker image by ID: docker rmi image-id
4. Dangling docker images none:none - https://projectatomic.io/blog/2015/07/what-are-docker-none-none-images/
5. Cleanup dangling docker images: docker rmi $(docker images -f "dangling=true" -q) --force, but that drops stage cache.
6. Images none:none remain until old containers that were created from them still exists, even if stopped.Source
7. To clear all dangling images without associated containers: docker image prune

Tip: to speed up docker build, use .dockerignore - https://docs.docker.com/engine/reference/builder/#dockerignore-file

Tip: Multistage builds, and run to specific stage - https://docs.docker.com/develop/develop-images/multistage-build/#stop-at-a-specific-build-stage

TODO: Try buildkit - https://docs.docker.com/engine/reference/builder/#buildkit

1. Use JRE instead of JDK for the final stage - https://adoptium.net/releases.html?variant=openjdk17&jvmVariant=hotspot
2. Use Adoptium Docker Hub - https://hub.docker.com/_/eclipse-temurin
3. Use alpine linux images - https://hub.docker.com/layers/eclipse-temurin/library/eclipse-temurin/17-jre-alpine/images/sha256-839f3208bfc22f17bf57391d5c91d51c627d032d6900a0475228b94e48a8f9b3?context=explore
4. Use scratch image for native apps - https://hub.docker.com/_/scratch

1. Check installed jenv versions: jenv versions
2. Download GraalVM binaries - https://github.com/graalvm/graalvm-ce-builds/releases
3. Extract it: tar -xvzf graalvm-ce-java11-22.1.0.tar.gz
4. Remove quarantine attribute on bits: sudo xattr -r -d com.apple.quarantine path/to/graalvm/folder/
5. Check where jenv stores java versions: jenv which java
6. Move new GraalVM JDK to the jenv versions folder: mv ~/graalvm-ce-java11-22.1.0 ~/.jenv/versions/graalvm-ce-java11-22.1.0
7. Add new JDK to jenv: jenv add ~/.jenv/versions/graalvm-ce-java11-22.1.0
8. Check that it was added: jenv versions
9. Use the new GraalVM JDK globally: jenv global graalvm-ce-java11-22.1.0
10. Check current java version: java -version
11. Add env variables to ~/.bashrc file:

export GRAALVM_HOME=~/.jenv/versions/graalvm-ce-java11-22.1.0

12. Reload source ~/.bashrc
13. Update PATH for the current session: export PATH=$GRAALVM_HOME/bin:$PATH, didn't save it to .bashrc since it is breaking jenv versions.
14. Test that gu command is available

Run: gu install native-image

Check it's available: native-image

In order to run native image with Docker from scratch, it needs to be static, meaning it will include all the dependencies that normally should be provided by OS environment.

To build static image add this param: --static

Note: as of now (Jul, 20222) MacOS doesn't support that option with error: DARWIN does not support building static executable images.

To allow app quit by pressing Ctrl + C this options needs to be added: --install-exit-handlers

If your app making http calls, this option needs to be added: --enable-url-protocols=http,https

• GraalVM Native Image Quick Reference

• Examples of Clojure libraries that support Graal Native Image build

• Native Image Options

• Reflection Use in Native Images

• GraalVM Native Image Tips & Tricks

• Fix GraalVM Native Image Build Issues

• Faster Clojure with GraalVM

• Using GraalVM Dashboard to inspect built image content