Dockerfile

# Multi-stage build for optimal image size
FROM maven:3.9-eclipse-temurin-17-alpine AS builder

WORKDIR /build

# Copy pom.xml and download dependencies (cached layer)
COPY pom.xml .
RUN mvn dependency:go-offline -B

# Copy source code and build
COPY src ./src
RUN mvn clean package -DskipTests

# Runtime stage
FROM eclipse-temurin:17-jre-alpine

# Install wget for healthchecks
RUN apk add --no-cache wget

WORKDIR /app

# Copy JAR from builder stage
COPY --from=builder /build/target/*.jar app.jar

# Memory optimization for container environments
ENV JAVA_OPTS="-Xmx256m \
               -Xms128m \
               -XX:+UseSerialGC \
               -XX:MaxRAM=256m \
               -XX:+TieredCompilation \
               -XX:TieredStopAtLevel=1 \
               -Djava.security.egd=file:/dev/./urandom"

# Create non-root user for security
RUN addgroup -g 1001 -S appgroup && \
    adduser -u 1001 -S appuser -G appgroup && \
    chown -R appuser:appgroup /app

USER appuser

EXPOSE 8080

HEALTHCHECK --interval=30s --timeout=3s --start-period=60s --retries=3 \
  CMD wget --quiet --tries=1 --spider http://localhost:8080/actuator/health || exit 1

ENTRYPOINT ["sh", "-c", "java $JAVA_OPTS -jar app.jar"]