Using OpenRewrite Recipes for Plugin Modernization or Automation Plugin Build Metadata Updates

Project goal: Explore ways OpenRewrite recipes can be used for Jenkins plugin modernization or automation of plugin build metadata updates

Skills to study/improve: OpenRewrite, Data structure (Trees) and visitor pattern, Java, Plugin hygiene and migration



OpenRewrite enables large-scale distributed source code refactoring for framework migrations, vulnerability patches, and API migrations via large-scale automated source code refactoring. While the original focus was on the Java language, OpenRewrite is continuously expanding language and framework coverage. The contributor will develop recipes to perform Jenkins plugin hygiene and migration tasks. It is hoped that through the completion of this project, the contributor will pick up skills in Java, OpenRewrite, and Jenkins plugin development.


The Jenkins ecosystem combines a monolithic core with a modular plugin system. True, this design provides a great degree of flexibility and robustness, yet also it poses challenges to propagating large-scale changes throughout the ecosystem. The lack of automation has led to many plugins falling behind with regard to ecosystem-wide migrations. This project proposes the creation of a new tool to apply generic transformations across the Jenkins ecosystem.

Example transformations include:

  • Ensuring that each plugin has a Jenkinsfile that conforms to the latest best practices from the Jenkins infrastructure team, including the use of containerized builds

  • Keeping the minimum Jenkins version reasonably current

  • Updating the plugin parent POM to the latest version

  • Migrating from explicit dependency versions to the Jenkins plugin BOM

  • Enabling incrementals

  • Updating plugin SCM URLs to conform to the latest GitHub best practices

  • Migrating from HTTP to HTTPs URLs wherever possible

  • Converting API dependencies to plugin dependencies

  • Replacing transitional <table>-based markup with <div>-based markup

  • Replacing JSR 305 annotations with SpotBugs annotations

  • Replacing deprecated JUnit assertions with Hamcrest assertions

  • Replacing deprecated Mockito method calls with non-deprecated equivalents

  • Replacing deprecated HTMLUnit method calls with non-deprecated equivalents

  • Migrating from JUnit 3 to JUnit 4

  • Replacing HudsonTestCase with JenkinsRule

  • Replacing RestartableJenkinsRule with JenkinsSessionRule

  • Replacing Guava, Apache Commons, and Joda Time with Java Platform equivalents

Quick Start

Use the "Contributing to Open Source" document and the "Modernizing Jenkins Plugins" video series to understand some of the transformations.

The scope of this project is to create a generic tool for applying these types of transformations against Jenkins plugins, validating the applied transformations, and creating pull requests with the results. While not all of the transformations described above will be implemented as part of this project, it is expected that a subset of the above list will be implemented to prove the viability of the newly-created tool.

Note that some of these transformations depend on other transformations, so a stack of transformations must be created and validated prior to creating the pull request.

The transformations range from editing Maven pom.xml files to applying automated refactorings to Java source code.

OpenRewrite provide APIs for Lossless Semantic Trees (LST) manipulation and transformation. Other framework like JDOM or Refaster could be used when implementing the recipes.

Expected outcomes

New feature will be developed towards the end of the project.

Details to be clarified interactively, together with the mentors, during the Contributor Application drafting phase.

Potential Mentors

Project Links

Organization Links

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