Helidon SE: use jlink to create minimal Java 11 runtime

Environment Details

• Helidon Version: 0.10.4
• Helidon SE
• JDK version: 11

Problem Description

We should determine the minimum set of modules needed to run a Helidon SE application and document it. Also, we should consider updating our quickstart Dockerfile to generate the JRE as part of a two stage docker build.

I did a quick experimentation and this seems to work, but I did not exercise very many code paths:

$JAVA_HOME/bin/jlink --compress=2 --output jre --add-modules java.base,java.logging,java.sql,java.desktop,java.management

[barchetta]

Example Dockerfile to generate image with custom JRE:

# Multistage docker build.
# Stage 1: Build custom Java 11 JRE and put it in /var/tmp/myjre
FROM openjdk:11-slim AS build
RUN ["jlink", "--compress=2", \
     "--add-modules", "java.base,java.logging,java.sql,java.desktop,java.management", \
     "--output", "/var/tmp/myjre"]

# Stage 2: Build application image using JRE from Stage 1
FROM debian:sid-slim
COPY --from=build /var/tmp/myjre /opt/jre
ENV PATH=$PATH:/opt/jre/bin

RUN mkdir /app
COPY libs /app/libs
COPY ${project.artifactId}.jar /app

CMD ["java", "-jar", "/app/${project.artifactId}.jar"]

[barchetta]

This is being documented in PR #182