Dockerfile

# ── Stage 1: Build ───────────────────────────────────────────────────────────
FROM eclipse-temurin:17-jdk-alpine AS build

WORKDIR /app

# Copy Maven wrapper and pom first — lets Docker cache the dependency layer
# so re-builds only re-download deps when pom.xml actually changes.
COPY mvnw .
COPY .mvn .mvn
COPY pom.xml .
RUN ./mvnw dependency:go-offline -q

# Copy source and package
COPY src src
RUN ./mvnw clean package -DskipTests -q

# ── Stage 2: Runtime ─────────────────────────────────────────────────────────
FROM eclipse-temurin:17-jre-alpine

WORKDIR /app

COPY --from=build /app/target/*.jar app.jar

EXPOSE 8080

# UseContainerSupport is on by default in Java 17 (respects cgroup memory limits).
# MaxRAMPercentage caps heap at 75% of the container's available memory.
ENTRYPOINT ["java", "-XX:MaxRAMPercentage=75.0", "-jar", "app.jar"]