# Stage 1: Build the application (The Build Stage)
# Use a Java SDK image with Maven pre-installed
FROM maven:3.9-jdk-17-slim AS build

# Set the working directory inside the container
WORKDIR /app

# Copy the Maven project files (pom.xml) first to leverage Docker layer caching
COPY pom.xml .

# Copy the source code
COPY src ./src

# Build the Spring Boot application, skipping tests to speed up the Docker build
# This creates the executable JAR file in the 'target' directory
RUN mvn clean package -DskipTests

# Stage 2: Create the final lightweight image (The Runtime Stage)
# Use a smaller Java Runtime Environment (JRE) image for a smaller footprint
FROM openjdk:17-jre-slim

# Set the working directory in the final image
WORKDIR /app

# Copy the built JAR file from the 'build' stage into the final image
# The JAR file is typically named 'target/<your-app-name>-<version>.jar'
# You may need to adjust the name if you have a non-standard pom.xml
COPY --from=build /app/target/*.jar app.jar

# Expose the default Spring Boot port
EXPOSE 8080

# Define the command to run the application
ENTRYPOINT ["java", "-jar", "app.jar"]