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More Kotlin (Gradle Composite Builds)

06 Jan 2025

Simplifying Exercise Projects with Gradle Composite Builds

Gradle composite builds are a good starting place to organize and modularize your build logic

see official documentation

Let’s explore a practical example of how to structure coding exercise projects without the need for an explicit top-level build file.

The Power of Convention Plugins

In our example repository, we’re using a convention-first approach for managing multiple coding exercise projects. Instead of maintaining a monolithic top-down build file, each exercise stands independently with its own build configuration, while sharing common build logic through convention plugins, where different exercises may need extra dependencies e.g for Json

How It Works

Look in our gradle/build-conventions directory, where we define our shared build logic. The key convention plugin griffio.exercise-conventions.gradle.kts provides:

To support writing Kotlin convention plugins, kotlin-dsl uses an embedded Kotlin version for plugin backwards compatibility

Benefits of This Approach

  1. Modularity: Each exercise project remains self-contained
  2. Consistency: Build conventions ensure uniform configuration across exercises
  3. Maintainability: Changes to build logic happen in one place
  4. Flexibility: Easy to override conventions at use-site with additional plugins

Example Structure

exercises-project/
 ├── gradle/
           │
           └── build-conventions/
                      └── src/main/kotlin/griffio.exercise-conventions.gradle.kts
 │
 ├── exercise-1/
               └── build.gradle.kts
               └── settings.gradle.kts
 │
 ├── exercise-2/
               └── build.gradle.kts
               └── settings.gradle.kts

Using the Convention Plugin

Each exercise simply needs to apply the convention:

plugins {
    id("griffio.exercise-conventions")
    id("griffio.something-custom")
}

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