Multi-Java

This container provides multiple Java runtimes for use with Pterodactyl eggs or any environment that needs to switch Java versions. OpenJDK 8, 11, 16, 17, 21 and 22 are installed.

Building and running

# Build each image
docker build -t Multi-OpenJDK:Headless -f OpenJDK/Headless/Dockerfile .
docker build -t Multi-OpenJDK:JRE -f OpenJDK/JRE/Dockerfile .
docker build -t Multi-OpenJDK:JDK -f OpenJDK/JDK/Dockerfile .
# Example run showing the selected JRE
docker run --rm -it -e STARTUP="java -version" Multi-OpenJDK:Headless

Configuration

Environment variables recognised by the image:

• JAVA_VERSION – default JRE version when .javaver is absent. Defaults to 22.
• STARTUP – command template executed on container start. {{VAR}} placeholders are expanded.
• TZ – optional timezone, default UTC.
• JAVA_DIR – directory of installed JREs (/opt/java). JAVA_HOME is derived from the chosen version.
• INTERNAL_IP – automatically populated with the container's internal address.

At runtime the entrypoint looks for a .javaver file in the working directory. If it contains a version number (for example 17) that version is used instead of JAVA_VERSION.

Publishing workflow

The repository uses a GitHub Actions workflow to publish the image to GitHub Container Registry. The workflow is triggered on pushes to main or via manual dispatch and builds a multi-arch image:

name: Build and Push Multi-Arch Docker Image to GHCR

on:
  workflow_dispatch:
  push:
    branches: [ main ]

jobs:
  build-and-push:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write
      id-token: write
    steps:
      - name: Checkout Repository
        uses: actions/checkout@v4
      - name: Set up QEMU
        uses: docker/setup-qemu-action@v3
      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3
      - name: Login to GitHub Container Registry
        uses: docker/login-action@v3
        with:
          registry: ghcr.io
          username: ${{ github.repository_owner }}
          password: ${{ secrets.GHCR_PAT }}
      - name: Build and Push Docker Images
        uses: docker/build-push-action@v5
        with:
          context: .
          platforms: linux/amd64,linux/arm64
          push: true
          tags: |
            ghcr.io/king-snakes/multi-openjdk:Headless
            ghcr.io/king-snakes/multi-openjdk:JRE
            ghcr.io/king-snakes/multi-openjdk:JDK

The resulting images are tagged as:

• ghcr.io/king-snakes/multi-openjdk:Headless
• ghcr.io/king-snakes/multi-openjdk:JRE
• ghcr.io/king-snakes/multi-openjdk:JDK