Multi Stage Dockerfile Explained Using Spring Boot Application
Use a multi-stage Dockerfile to build a Spring Boot app cleanly and run only the final JAR.
A multi-stage Dockerfile uses more than one FROM instruction.
Each stage has a job. One stage can build the application, and another stage can run it. The final image only keeps what you copy into the final stage.
This is the cleanest way to dockerize many production applications.
Multi-stage Spring Boot Dockerfile
FROM maven:3.9-eclipse-temurin-17 AS build
WORKDIR /app
COPY pom.xml .
COPY src ./src
RUN mvn clean package -DskipTests
FROM eclipse-temurin:17-jre
WORKDIR /app
COPY --from=build /app/target/*.jar app.jar
EXPOSE 8080
CMD ["java", "-jar", "app.jar"]Stage 1: build
FROM maven:3.9-eclipse-temurin-17 AS buildThis stage has Maven and Java. It is used to compile the application and create the JAR.
RUN mvn clean package -DskipTestsAfter this, the JAR exists inside the build stage.
Stage 2: runtime
FROM eclipse-temurin:17-jreThis stage is smaller because it only needs Java runtime.
COPY --from=build /app/target/*.jar app.jarThis copies only the built JAR from the build stage into the final image.
Why this is better
The final image does not contain Maven, source code, or build cache.
| Single-stage | Multi-stage |
|---|---|
| Build and run in one image | Build and run in separate stages |
| Larger final image | Smaller final image |
| Includes build tools | Runtime only |
| Easier for beginners | Better for production |
Build and run
docker build -t spring-multistage:1.0 .
docker run -d -p 8080:8080 --name spring-app spring-multistage:1.0Check logs:
docker logs spring-appMulti-stage builds let Docker use heavy tools while building, then leave those tools behind in the final runtime image.
Written By: Shiva Srivastava
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