spring-petclinic/Dockerfile

# Multi-stage Dockerfile for Spring PetClinic
# Stage 1: Build
FROM eclipse-temurin:21-jdk-jammy AS builder

WORKDIR /app

# Copy Maven wrapper and pom.xml for dependency caching
COPY .mvn/ .mvn/
COPY mvnw pom.xml ./

# Download dependencies
RUN ./mvnw dependency:go-offline -B

# Copy source code
COPY src ./src

# Build application
RUN ./mvnw clean package -DskipTests -B

# Extract JAR layers for better caching
RUN mkdir -p target/extracted && \
    java -Djarmode=layertools -jar target/*.jar extract --destination target/extracted

# Stage 2: Runtime
FROM eclipse-temurin:21-jre-jammy

# Install curl for health checks
RUN apt-get update && \
    apt-get install -y --no-install-recommends curl && \
    apt-get clean && \
    rm -rf /var/lib/apt/lists/*

# Create non-root user
RUN groupadd -r spring && useradd -r -g spring spring

WORKDIR /app

# Copy extracted layers from builder
COPY --from=builder /app/target/extracted/dependencies/ ./
COPY --from=builder /app/target/extracted/spring-boot-loader/ ./
COPY --from=builder /app/target/extracted/snapshot-dependencies/ ./
COPY --from=builder /app/target/extracted/application/ ./

# Change ownership
RUN chown -R spring:spring /app

# Switch to non-root user
USER spring:spring

EXPOSE 8080

# Health check
HEALTHCHECK --interval=30s --timeout=3s --start-period=60s --retries=3 \
    CMD curl -f http://localhost:8080/actuator/health || exit 1

# JVM options for containers
ENV JAVA_OPTS="-XX:+UseContainerSupport -XX:MaxRAMPercentage=75.0"

# Run application
ENTRYPOINT ["sh", "-c", "java $JAVA_OPTS org.springframework.boot.loader.launch.JarLauncher"]