echo-app-kt 🗣️

A Kotlin multi-module project demonstrating the use of convention plugins to centralize build configuration and promote consistency across subprojects.

📦 Overview

This project showcases how to set up and apply a custom convention plugin using Kotlin DSL in Gradle. Convention plugins are ideal for sharing common configuration logic such as:

• Applying shared plugins like kotlin("jvm")
• Setting a unified Java toolchain version
• Managing dependencies using a central version catalog (libs.versions.toml)

By applying the convention plugin to each subproject, we ensure consistent build behavior with minimal duplication.

📁 Project Structure

.
├── app/                 # Application module
│   └── src/main/kotlin/
├── lib/                 # Library module
│   └── src/main/kotlin/
├── convention-plugins/  # Custom convention plugin module
│   └── src/main/kotlin/
├── gradle/
│   └── wrapper/
└── settings.gradle.kts  # Includes the convention plugin module

🔧 How It Works

The convention-plugins module contains reusable Gradle scripts, including:

// convention-plugins/src/main/kotlin/jvm.conventions.gradle.kts

plugins {
    kotlin("jvm")
}

kotlin {
    jvmToolchain {
        languageVersion = JavaLanguageVersion.of(21)
    }
}

This script applies the Kotlin JVM plugin and configures Java 21 as the toolchain.

🔗 Centralized Dependency Management

The project uses a shared libs.versions.toml file in gradle/:

[versions]
kotlin = "2.1.20"

This version is used consistently across all modules by referencing libs.kotlin.gradle.plugin inside the convention plugin's build.gradle.kts.

⚠️ Note on @Suppress("UnstableApiUsage")

Gradle currently treats the repositories block inside dependencyResolutionManagement as unstable, emitting a warning. We suppress this warning explicitly to keep builds clean:

@Suppress("UnstableApiUsage")
dependencyResolutionManagement {
    // ...
}

🚀 How to Build

To compile the entire project:

./gradlew build

To verify that the Kotlin plugin was correctly applied to app, run:

./gradlew --quiet app:dependencies | grep kotlin

If you see Kotlin-related dependencies, your convention plugin is working 🎉

💡 Why This Matters

Using convention plugins early in your project helps:

• Reduce boilerplate across modules
• Improve maintainability and scalability
• Ensure consistent configuration across teams

🛠 Kotlin Version

This project uses Kotlin 2.1.20.