Multi-stage Docker builds in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to specify the base image for building the Spring Boot app.

Spring Boot

FROM [1] AS build

Drag options to blanks, or click blank then click option'

Aubuntu:latest

Bopenjdk:17-jdk-slim

Cnode:18-alpine

Dpython:3.12-slim

Attempts:

3 left

💡 Hint

Common Mistakes

Using a non-Java base image like Ubuntu or Node.js causes build errors.

Choosing a JDK version incompatible with the app.

The base image openjdk:17-jdk-slim provides the Java 17 environment needed to build the Spring Boot app.

2fill in blank

medium

Complete the code to copy the Maven wrapper and project files into the build image.

Spring Boot

COPY [1] ./

Drag options to blanks, or click blank then click option'

Asrc

BDockerfile

Cmvnw pom.xml

Dtarget

Attempts:

3 left

💡 Hint

Common Mistakes

Copying only the source folder without build files.

Copying the Dockerfile instead of project files.

Copying mvnw and pom.xml is necessary to run Maven build commands inside the image.

3fill in blank

hard

Fix the error in the build command to package the Spring Boot app.

Spring Boot

RUN ./mvnw clean [1] -DskipTests

Drag options to blanks, or click blank then click option'

Ainstall

Bcompile

Cspring-boot:run

Dverify

Attempts:

3 left

💡 Hint

Common Mistakes

Using compile only compiles but does not package the jar.

Using spring-boot:run runs the app instead of building.

The install goal compiles and packages the app and installs it to the local Maven repository, which is suitable for building the jar.

4fill in blank

hard

Fill both blanks to specify the runtime image and copy the built jar from the build stage.

Spring Boot

FROM [1] AS runtime
COPY --from=build [2] /app/app.jar

Drag options to blanks, or click blank then click option'

Aopenjdk:17-jre-slim

B/target/*.jar

C/build/libs/app.jar

Dopenjdk:17-jdk-slim

Attempts:

3 left

💡 Hint

Common Mistakes

Using the JDK image for runtime unnecessarily increases image size.

Copying from wrong build output folder.

The runtime stage uses a lightweight JRE image openjdk:17-jre-slim. The built jar is usually in the target folder after Maven build.

5fill in blank

hard

Fill all three blanks to complete the command that runs the Spring Boot jar with memory options.

Spring Boot

ENTRYPOINT ["java", [1], [2], "-jar", [3]]

Drag options to blanks, or click blank then click option'

A"-Xms256m"

B"-Xmx512m"

C"/app/app.jar"

D"-Dspring.profiles.active=prod"

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting memory options can cause performance issues.

Placing the jar path before -jar causes errors.

The ENTRYPOINT runs the jar with initial and max heap size options -Xms256m and -Xmx512m, followed by the path to the jar.