Recommended setup for formatting files with Spotless

[tschaffter]

I'm exploring how to use Spotless to format Java code in the context of an Nx monorepo. The idea came thanks to this generator, which configures Gradle and Maven projects to format files with Spotless. In this context, it is important to note that Spotless can be used to format files for different languages and file types (e.g. .md, .sql, etc.).

A nice-to-have feature for my team is that files are automatically formatted when saving files. This gives the developer a chance to review immediately the final code before closing the files. A similar approach - less real-time - would be to programmatically run the formatter in a pre-commit git hook, for example. The review of the formatted files would then be performed via the PR review.

The VS Code extension Spotless Gradle suggested by the Spotless project is built on top of Spotless + Gradle to provide IntelliSense and formatting on save. This plugin has the following requirements:

• The activation of the extension requires gradlew (or gradle.bat) to be included in the workspace root folder.
  • Installing the Gradle binary globally may also work (not tested).
• The file build.gradle with the following content or similar must be included in the workspace root folder.

  plugins {
    id 'com.diffplug.spotless' version '6.8.0'
  }
  
  repositories {
    mavenCentral()
  }
  
  spotless {
    java {
      target 'apps/**/src/*/java/**/*.java', 'libs/**/src/*/java/**/*.java'
  
      importOrder()
      removeUnusedImports()
      googleJavaFormat()
    }
  }

To summarize, the above configuration enables:

• Workspace-level Spotless configuration in place of duplicated project-level configuration.
• Java files are automatically formatted when saved in VS Code.
• The VS Code extension Spotless Gradle provide Spotless-related IntelliSense to build.gradle.

One drawback of this approach compared to the project-level Spotless configuration generated by this generator is that I loose the caching mechanism provided by Nx (e.g. if the project task format-check is added to the list of cacheable Nx tasks). For example, git hooks and CI workflows would run faster if only the files/projects that have been changed have their format checked.

Is there a way for a project-specific build.gradle to inherit the Spotless configuration defined in the workspace-level build.gradle? This way we would have a unique Spotless configuration that is easier to maintain and update, while still benefiting from Nx cache and parallel/distributed execution.

[tinesoft]

Hi Thomas,

Sorry for the late answer, I've been very busy, and forgot about this discussion.

What you are asking for, goes beyond just formatting. The need can arise for any other dependency/config,
you want to centralize at a root level. Basically, it means being able to support multi-module spring boot projects.
This is something Spring-boot does not (yet) support out-of-the-box, see spring-io/initializr#663

I'd like this plugin to be as closed as possible to what Spring Initiliaz'r API generates, which is why I've been reluctant to change
this part of the generated code in this plugin...

Nonetheless, I'm monitoring the aforementioned issue from Spring.

[tschaffter]

Thanks for the great reply and for the link to the ticket. I'm happy with the modularity of my current setup (https://github.com/Sage-Bionetworks/challenge-registry). Being able to centralize Java dependencies like with npm dependencies would be a plus but it's definitively not a deal breaker.