Java Hello World — Docker Samples

A pedagogical repository demonstrating advanced strategies to containerize Java applications, evolving from legacy JVM builds to hyper-optimized native binaries. This project is designed for Master's-level students to explore the intersection of Java, containerization, and modern security practices.

The Benchmark Application (App.java)

The included Java application simulates a microservice workload to allow for comparative performance analysis:

1. Memory Allocation: Generates a synthetic dataset of strings based on APP_ITERATIONS.
2. CPU Processing: Executes a filter operation to measure processing latency.
3. Resilience: Pauses for APP_SLEEP_MS to allow resource monitoring (e.g., docker stats) before termination.
4. Observability: Logs JVM vendor, version, and execution metrics to compare runtime environments.

Dockerfile Progression

The repository follows a clear architectural evolution:

Dockerfile	Strategy	Purpose
10.maven	Baseline	Single-stage Maven build for development/debugging.
20.stage	Multi-stage	Separates build dependencies from runtime to reduce image size.
30.cache	BuildKit	Uses persistent BuildKit cache mounts to accelerate CI/CD cycles.
40.manual	Manual Toolchain	Provisioning environments using SDKMAN for strict control.
50.jlink	JLink Modulith	Slices a custom, minimal JRE to remove unnecessary JDK modules.
51.jlink-alpine	Alpine Modulith	Deploys the JLink slice on an alpine:3.20 base for minimal footprint.
60.graalvm	Dynamic Native	AOT-compiled native binary running on Distroless.
61.graalvm-static	Static Native	Fully static musl binary on Distroless Static (zero OS dependencies).

Build & Run

To build and execute the entire series sequentially, use the provided helper script:

./build_and_run_all.sh

Maven Profiles

The project uses custom profiles to adapt the build lifecycle for each strategy:

• -Pjvm: Configures maven-jar-plugin for thin JARs and maven-dependency-plugin for runtime libraries.
• -Pjlink: Triggers maven-jlink-plugin to generate a custom modular runtime image.
• -Pnative: Configures native-maven-plugin for GraalVM AOT compilation.
• -Pnative-static: Forces musl libc compilation for fully static native binaries.

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Maintained by Emmanuel Bruno, University of Toulon.