Google's Jib Gaining Traction in the Broader Java Dev Ecosystem

Google introduced the beta version of its open-source Jib tool for containerizing Java applications in July 2018 with relatively little fanfare. Two years later, the tool has put on some serious muscle in the form of new features and plug-ins, and quietly become a developer favorite.

Jib is an open-source Java tool maintained by Google for building Docker images of Java applications. Jib 1.0.0, released to general availability last year, was designed to eliminate the need for deep Docker mastery. It effectively circumvented the need to install Docker, run a Docker daemon, and/or write a Dockerfile.

Jib accomplishes this by separating the Java application into multiple layers for more granular incremental builds. (Traditionally, a Java app is built as a single image layer with the application JAR.) "When you change your code, only your changes are rebuilt, not your entire application," the GitHub page explains. "These layers, by default, are layered on top of a distro-less base image."

"Jib has come a long way since it went GA," wrote Google software engineers Chanseok Oh and Appu Goundan in a blog post, "and now has a sizable community around it. The core Jib team has been working hard to expand the ecosystem, and we're confident that the community will only grow larger."

For example, Google publishes Jib as both a Maven and a Gradle plugin. The GitHub repository of Jib extensions to those plugins--the Jib Extension Framework, published in June-- enables users to easily extend and tailor the Jib plugins behavior. Jib extensions are supported from Jib Maven 2.3.0 and Jib Gradle 2.4.0.

"We think that the extension framework opens up a lot of possibilities, from fine-tuning image layers to containerizing GraalVM native images for fast startup or jlink images for small footprint," Oh and Goundan, said. 

Google published first-party Jib Maven and Gradle extensions to cover the Quarkus framework's "special containerization needs." (It was already possible to direct Quarkus to create an optimized image with the core Jib engine without applying the Jib build plugin.) Using the Jib build plugins enables finer-grained control over how to build and configure an image compared with Quarkus' built-in Jib engine-powered containerization.

Google has also put some effort into supporting the implementation of first-party integration for Spring Boot in Jib. For example, Jib's packaged containerizing-mode now works out of the box for Spring Boot, containerizing the original thin JAR rather than the fat Spring Boot JAR that's unsuitable for containerization.

Finally, Google has made sure that Jib works out of the box with Skaffold File Sync. Skaffold is a command line tool that facilitates continuous development for Kubernetes-native applications. Using the keyword auto, developers can take advantage of remote file synchronization to a running container with zero sync configuration.

Posted by John K. Waters on August 25, 2020