# Build stage: uses Maven + JDK 17 (Alpine) to compile and package the application.
FROM maven:3.9-eclipse-temurin-17-alpine AS builder
WORKDIR /app

# Copy pom.xml first to leverage Docker layer caching for dependency downloads.
COPY pom.xml .
RUN mvn dependency:go-offline -q

# Copy source and build the fat JAR, skipping tests.
COPY src ./src
RUN mvn clean package -DskipTests -q

# Runtime stage: slim JRE-only image for a smaller production footprint.
FROM eclipse-temurin:17-jre-alpine
WORKDIR /app
COPY --from=builder /app/target/*.jar app.jar
EXPOSE 8080
ENTRYPOINT ["java", "-jar", "app.jar"]