Dockerfile

# Stage 1: Build
FROM eclipse-temurin:21-jdk-alpine AS build
WORKDIR /app
COPY .mvn .mvn
COPY mvnw pom.xml ./
RUN chmod +x mvnw && ./mvnw dependency:go-offline -B
COPY src ./src
RUN ./mvnw package -DskipTests -B

# Stage 2: Extract layers for optimal Docker caching
FROM eclipse-temurin:21-jdk-alpine AS extract
WORKDIR /app
COPY --from=build /app/target/*.jar app.jar
RUN java -Djarmode=layertools -jar app.jar extract

# Stage 3: Runtime (minimal JRE image)
FROM eclipse-temurin:21-jre-alpine
WORKDIR /app
COPY --from=extract /app/dependencies/ ./
COPY --from=extract /app/spring-boot-loader/ ./
COPY --from=extract /app/snapshot-dependencies/ ./
COPY --from=extract /app/application/ ./
EXPOSE 48080
ENTRYPOINT ["java", "-Xmx384m", "-Xms256m", "org.springframework.boot.loader.launch.JarLauncher"]