Multi-stage Docker builds in Spring Boot - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a multi-stage Docker build?

A multi-stage Docker build uses multiple steps in one Dockerfile to create smaller, efficient images by separating build and runtime environments.

beginner

Why use multi-stage builds for Spring Boot applications?

They help create smaller images by compiling the app in one stage and copying only the needed files to the final image, improving speed and security.

intermediate

In a multi-stage Dockerfile, what does the AS keyword do?

It names a build stage so you can refer to it later to copy files from that stage into another stage.

intermediate

What is copied from the build stage to the final stage in a Spring Boot multi-stage Docker build?

Usually the compiled JAR file and any necessary runtime files are copied to keep the final image small and clean.

advanced

How does multi-stage build improve security?

By excluding build tools and source code from the final image, it reduces attack surface and leaks of sensitive data.

What is the main benefit of using multi-stage Docker builds?

A More layers in the image

B Faster internet download

C Automatic code debugging

D Smaller and cleaner final images

Multi-stage builds help create smaller images by separating build and runtime stages.

In a Dockerfile, how do you name a build stage?

A Using the AS keyword

B Using the FROM keyword twice

C Using the COPY command

D Using the RUN command

The AS keyword names a stage so you can copy files from it later.

What file is typically copied from the build stage in a Spring Boot multi-stage build?

A The compiled JAR file

B The source code files

C The Dockerfile

D The Maven settings file

The compiled JAR is the runnable artifact copied to the final image.

Which of these is NOT a reason to use multi-stage builds?

A Reduce image size

B Improve build speed

C Include build tools in final image

D Enhance security by excluding source code

Multi-stage builds exclude build tools from the final image to keep it clean.

What command copies files from a named build stage to another stage?

A RUN --from=stageName

B COPY --from=stageName

C ADD --from=stageName

D FROM --copy=stageName

COPY --from=stageName copies files from a previous build stage.

Explain how a multi-stage Docker build works for a Spring Boot application.

Think about building first, then packaging only what is needed.

Describe the benefits of using multi-stage Docker builds in terms of image size and security.

Focus on what is left out of the final image.