How to Streamline the Java Application Containerization Process

With an estimated 70% of Java applications running inside containers, Docker has become standard in the Java community. Stack Overflow found that Docker ranked as both the most-desired and most-used developer tool.

Building quality Dockerfiles presents challenges for application developers who may lack proper training. Criteria for quality include container launch speed and size, Dockerfile structure and standards, security, and JVM configuration flags.

Jib

Jib, an open source project by Google, enables developers to build Java container images without Docker expertise or Dockerfile knowledge. Available via Maven and Gradle plugins, as well as a CLI, Jib streamlines the process through intelligent layering.

The tool rebuilds and pushes only changed application layers, resulting in faster, more efficient builds. It supports multi-module projects, automatically handling dependencies between modules. Jib integrates with container registries for secure image builds and doesn't require a local Docker daemon, making it compatible with development machines, CI/CD pipelines, and cloud-based build services.

Basic usage is straightforward:

$ mvn compile jib:build
$ mvn compile jib:dockerBuild

With 13,000 GitHub stars, Jib is a community favorite.

Buildpacks

Cloud Native Buildpacks, created by Pivotal and Heroku and managed by the CNCF, converts application code directly into running images without Dockerfile knowledge.

Buildpacks offer comparable features to Jib plus additional capabilities: SBOM generation, advanced caching mechanisms, and base image updates without rebuilds. Support extends to Node.js, .NET Core, Go, Python, PHP, and Ruby.

Base images come from providers like Google, Heroku, and Paketo, leveraging their knowledge and best practices. These providers maintain quick turnarounds for OS and library security fixes.

Building an image requires one command:

pack build samples/java --path java/maven

Conclusion

Both Jib and Buildpacks streamline Java container image building, ensuring correct construction while automating integration into continuous delivery pipelines. Jib excels at speed and smaller image sizes, while Buildpacks offers more features and broader language support. Either choice represents a significant improvement over manual Dockerfile creation.