Deploying a Java SpringBoot application to Docker and Kubernetes involves building a container image that bundles the application with its dependencies and environment. There are two methods of building a container image: Spring Cloud Native Buildpacks and Dockerfile.

Dockerfile

Dockerfile is the oldest and most common way to build container images. It is a text file that contains a series of instructions to compile the source code and assemble the layers of a container image. Dockerfile gives you full control and flexibility over how your image is built, but it also comes with some drawbacks.

Advantages

  • Full control and flexibility over how your image is built.

Disadvantages

  • You need to write and maintain the Dockerfile yourself, which can be error-prone and time-consuming.
  • You also need to ensure that your image is secure, up-to-date, and compliant with best practices.

Example

Here is an example Dockerfile for a java/spring boot app:

FROM eclipse-temurin:17-jre-alpine
WORKDIR /opt/app
RUN addgroup --system javauser && adduser -S -s /usr/sbin/nologin -G javauser javauser
COPY target/*.jar app.jar
RUN chown -R javauser:javauser .
USER javauser
ENTRYPOINT ["java", "-jar", "app.jar"]

To build the Docker image, run a command similar to this one:

docker build -t myorg/myapp .

Spring Cloud Native Buildpacks

Spring Cloud Native Buildpacks are a newer and simpler way to build container images from source code. They are based on the Cloud Native Buildpacks project, which aims to provide a standard way to convert source into a container without requiring a Dockerfile.

Spring Cloud Native Buildpacks use a set of pre-defined buildpacks that detect your application type, language, and dependencies, and then automatically create a container image for you. You can use Spring Cloud Native Buildpacks directly from Maven or Gradle with a single command, without needing to install or configure anything else. Spring Cloud Native Buildpacks also ensure that your image is secure, optimized, and compliant with best practices.

Advantages

  • Simpler and faster to use than Dockerfile.
  • More secure than Dockerfile.
  • Ensure that your image is secure, optimized, and compliant with best practices.

Disadvantages

  • Less flexible than Dockerfile.

Example

For example in our case, just run the next command:

./mvnw spring-boot:build-image -Dspring-boot.build-image.imageName=myorg/myapp

Comparing Dockerfile and Spring Cloud Native Buildpacks

  • Simplicity: Spring Cloud Native Buildpacks are simpler and faster to use than Dockerfile. You don’t need to write or maintain any configuration files or scripts. You just need to run one command and let the buildpacks do the work for you.
  • Security: Spring Cloud Native Buildpacks are more secure than Dockerfile. They use trusted and verified base images and dependencies that are regularly updated and patched. They also apply security best practices such as minimizing the attack surface, dropping privileges, and scanning for vulnerabilities.
  • Flexibility: Dockerfile is more flexible than Spring Cloud Native Buildpacks. You can customize every aspect of your image build process and use any tools or frameworks you want. You can also leverage the large ecosystem of existing Dockerfiles and images available online.
  • Portability: Both Spring Cloud Native Buildpacks and Dockerfile produce Docker compatible images that you can run anywhere. However, Spring Cloud Native Buildpacks have some advantages in terms of portability. They use layered images that can be reused and cached across builds, reducing the size and bandwidth of your images. They also support reproducible builds that ensure consistent results regardless of where or when you build your images.

Conclusion

In conclusion, Spring Cloud Native Buildpacks and Dockerfile are two different methods for building container images from source code. Each method has its pros and cons depending on your needs and preferences.

If you value simplicity, security, and portability over flexibility, you might want to try Spring Cloud Native Buildpacks.

If you value flexibility, control, and customization over simplicity, you might want to stick with Dockerfile.