ragedunicorn/java repository overview

⁠Java (Eclipse Temurin) Alpine Docker Image

A minimal Java image on Alpine Linux, shipping Eclipse Temurin 21 (LTS) from the Adoptium apk repository in two variants: a full JDK with Apache Maven and a runtime-only JRE.

⁠Quick Start

# Pull the JDK (latest)
docker pull ragedunicorn/java:latest

# Pull the JRE
docker pull ragedunicorn/java:latest-jre

# Or pull a specific version
docker pull ragedunicorn/java:21.0.11-jdk-alpine3.24.1-1

# Print the Java version (default command)
docker run --rm ragedunicorn/java:latest

# Run a Java source file (JDK only)
docker run -v $(pwd):/app ragedunicorn/java:latest Hello.java

⁠Features

• 🚀 Small footprint: compact runtime image built on Alpine Linux
• ☕ Eclipse Temurin 21 LTS: pinned Adoptium build, decoupled from Alpine
• 📦 Apache Maven: pinned official binary in the JDK variant, decoupled from Alpine
• 🔀 Two variants: full JDK (latest) and runtime-only JRE (latest-jre)
• 🔒 Security: non-root user, minimal attack surface
• 🏗️ Multi-platform: supports linux/amd64 and linux/arm64
• 🎯 Customizable: extend with only what you need

⁠Usage Examples

⁠Run a Java source file (single-file source launch, JDK only)

docker run -v $(pwd):/app ragedunicorn/java:latest Hello.java

⁠Run a jar with the JRE

docker run -v $(pwd):/app ragedunicorn/java:latest-jre -jar app.jar

⁠Interactive Java shell (JDK only)

docker run -it --rm --entrypoint jshell ragedunicorn/java:latest

⁠Compile with javac (JDK only)

docker run -v $(pwd):/app --entrypoint javac ragedunicorn/java:latest Hello.java

⁠Build with Maven (JDK only)

# The named volume keeps the local repository (~/.m2) between runs; a fresh
# volume is initialized owned by the java user (the image pre-creates ~/.m2)
docker run -v $(pwd):/app -v m2cache:/home/java/.m2 --entrypoint mvn ragedunicorn/java:latest package

On Docker Desktop for Windows, overwriting existing files on a bind mount can fail with Operation not permitted for the non-root java user — if your build writes into the mounted workspace, run with -u root and use -v m2cache-root:/root/.m2 for the cache instead.

⁠Build a custom image

FROM ragedunicorn/java:latest-jre

COPY app.jar /app/app.jar

CMD ["-jar", "/app/app.jar"]

⁠Tags

This image uses semantic versioning that includes all component versions:

Format: {java_version}-{jdk|jre}-alpine{alpine_version}-{build_number}

⁠Version Examples

• 21.0.11-jdk-alpine3.24.1-1 - Temurin 21.0.11 JDK on Alpine 3.24.1, build 1
• 21.0.11-jre-alpine3.24.1-1 - Temurin 21.0.11 JRE on Alpine 3.24.1, build 1
• latest - Most recent stable JDK release
• latest-jre - Most recent stable JRE release

Both variants are published together from a single release. When updates are available through automated dependency management, new releases are created with appropriate version tags.

⁠Environment Variables

• JAVA_HOME - Points at the Temurin installation (/usr/lib/jvm/java-21-temurin in the JDK, /usr/lib/jvm/java-21-temurin-jre in the JRE)
• MAVEN_HOME - Points at the Maven installation (/opt/maven, JDK only)
• LANG=C.UTF-8 - UTF-8 default encoding

⁠Working Directory

The default working directory is /app. Mount your code here:

docker run -v $(pwd):/app ragedunicorn/java:latest YourProgram.java

⁠Links

• GitHub: https://github.com/ragedunicorn/docker-java⁠
• Issues: https://github.com/ragedunicorn/docker-java/issues⁠
• Releases: https://github.com/ragedunicorn/docker-java/releases⁠
• Eclipse Temurin: https://adoptium.net/⁠

⁠License

MIT License - See GitHub repository⁠ for details.