src/main/docker/Dockerfile.alpine-jlink

# Ultra-minimal Alpine + Custom JRE
# Expected size: ~120-160MB

# Stage 1: Create custom JRE with only needed modules
FROM eclipse-temurin:21-jdk-alpine as jre-builder
WORKDIR /app

# Analyze JAR to find required modules
COPY build/libs/*.jar app.jar
RUN jdeps --ignore-missing-deps --print-module-deps app.jar > modules.txt

# Create minimal JRE with only required modules
RUN jlink \
    --add-modules $(cat modules.txt),java.logging,java.xml,java.sql,java.naming,java.desktop,java.management,java.security.jgss,java.instrument \
    --strip-debug \
    --no-man-pages \
    --no-header-files \
    --compress=2 \
    --output /custom-jre

# Stage 2: Production image
FROM alpine:3.19
RUN apk add --no-cache tzdata && \
    addgroup -g 1001 -S appgroup && \
    adduser -u 1001 -S appuser -G appgroup

# Copy custom JRE
COPY --from=jre-builder /custom-jre /opt/java
ENV JAVA_HOME=/opt/java
ENV PATH="$JAVA_HOME/bin:$PATH"

WORKDIR /app
COPY build/libs/*.jar app.jar
RUN chown appuser:appgroup app.jar

USER appuser
EXPOSE 8080

ENTRYPOINT ["java", \
    "-XX:+UseContainerSupport", \
    "-XX:MaxRAMPercentage=70.0", \
    "-XX:+UseG1GC", \
    "-jar", "app.jar"]