kotlin-tools

Gradle Plugins

A collection of Gradle plugins for building applications and libraries using Kotlin.

These plugins all target Kotlin 2.4.0 and Java 21 (for Kotlin libraries), Java 25 (for Kotlin apps) and Java 17 (for Gradle plugins). The plugins require Gradle 9.0 or later and Java 17 or later.

Settings plugins

net.rubygrapefruit.kotlin-base

A settings plugin that must be applied to the settings of any build that uses these plugins.

• Applies the foojay toolchain convention plugin.

Native applications

net.rubygrapefruit.native.cli-app

Builds a command-line application implemented in Kotlin multiplatform that targets native desktop platforms.

• Supports Linux x64, Windows x64 and macOS arm64 targets.
• Does not define any targets, these have to be explicitly defined.
• Adds unixMain and unixTest source sets for Kotlin code that is shared by macOS and Linux targets.
• Adds an application { } block, see below for the available settings.
• Add dist and install tasks.

This uses the net.rubygrapefruit.native.base-cli-app plugin and adds the targets.

net.rubygrapefruit.native.ui-app

Builds a UI application implemented in Kotlin multiplatform that targets native desktop platforms.

• Adds macOS arm64 target.
• Adds an application { } block, see below for the available settings.
• Add dist task.

Native and JVM libraries

net.rubygrapefruit.kmp.lib

Builds a library implemented in Kotlin multiplatform that targets the JVM, browser and native desktop platforms.

• Supports JVM (versions 11-26), browser, Linux and Windows x64 targets and macOS x64 and arm64 targets.
• Does not define any targets, these have to be explicitly defined.
• Adds library { } block, see below for the available settings.
• Adds unixMain and unixTest source sets for Kotlin code that is shared by macOS and Linux targets.
• Adds desktopMain and desktopTest source sets for Kotlin code that is shared by JVM, macOS, Linux and Windows targets.
• Generates a module-info for the JVM target.

JVM applications and libraries

Supports JVM versions 11-26.

net.rubygrapefruit.jvm.lib

Builds a library implemented using Kotlin/JVM.

• Adds library { } block, see below for the available settings.
• Generates a module-info.

net.rubygrapefruit.jvm.cli-app

Builds a command-line application implemented using Kotlin/JVM. Expects that the application uses the JVM module system.

• The distribution contains the jars for the application and a launcher script. This script requires that a compatible JVM can be found on the machine’s $PATH, unless one of the plugin below is also used.
• The launcher script starts the application in the debugger when $JVM_DEBUG is set to a non-empty string
• Adds application { } block, see below for the available settings.
• Automatically determines the application main class.
• Generates a module-info.
• Add dist and install tasks.

net.rubygrapefruit.jvm.embedded-jvm

Can be applied with net.rubygrapefruit.jvm.cli-app to include a copy of the JVM in the application distribution. The launcher script uses this embedded JVM. Uses jlink to create the JVM image.

net.rubygrapefruit.jvm.native-binary

Can be applied with net.rubygrapefruit.jvm.cli-app to create a native binary to use in the application distribution, instead of using a launcher script. Uses graalvm to create the native binary.

net.rubygrapefruit.jvm.ui-app

Builds a desktop UI application implemented using Kotlin/JVM and that presents a Swing or JavaFX UI. Expects that the application uses the JVM module system.

• Creates a debug (unsigned) macOS application bundle and a release (signed and notarized) application bundle
• Includes an embedded JVM in the application bundle
• Provides an application icon, default location is src/main/Icon1024.png
• Adds application { } block, see below for the available settings.
• Use dist task to build the debug application bundle.

Gradle plugins

net.rubygrapefruit.gradle-plugin

A convention plugin for implementing Gradle plugins using Kotlin/JVM.

• Adds dependencies and repository definitions so that a fixed version of Kotlin (currently 2.4.0) is used to compile the plugin.
• Targets Java 17.
• Adds versions extension
• Adds a dependency on these plugins, so their API can be used in other plugins.
• Adds a pluginBundle { } block.

Common application settings for all targets

• Adds application { } block
  • application.appName - the base name for the application, used for various default file names.
  • application.distribution.imageDirectory - the directory to create the distribution image in.
• Adds a dist task to create a distribution image containing the app ready for installation. By default, this is created in build/dist-image

JVM application settings

• Adds application { } block
  • application.mainClass - defaults to main class determined by inspecting the bytecode
  • application.module.name - defaults to the application name
  • application.targetJvmVersion - defaults to 25
  • application.dependencies { } - production dependencies
  • application.test { } - test dependencies

JVM library settings

• Adds library { } block
  • library.module.name - defaults to the project name
  • library.module.exports
  • library.module.requires - calculated from compile (implementation) dependencies
  • library.module.requiresTransitive - calculated from the API dependencies
  • library.targetJvmVersion - defaults to 17
  • library.dependencies { } - production dependencies
  • library.test { } - test dependencies

Native application settings

• Adds application { } block
  • application.desktopNative() - adds Windows, Linux, and macOS as targets
  • application.macOS() - adds macOS as a target
  • application.common { } - production dependencies common to all targets
  • application.test { } - test dependencies common to all targets

Multi-platform library settings

• Adds library { } block
  • library.jvm { } - adds the JVM as a target with the given settings (same as JVM library above)
  • library.desktopNative() - adds Windows, Linux, and macOS as targets
  • library.macOS() - adds macOS as a target
  • library.browser() - adds the browser as a target
  • library.common { } - production dependencies common to all targets
  • library.test { } - test dependencies common to all targets

UI applications

• $APP_SIGNING_IDENTITY - signing certificate name in macOS keychain. Should reference a “Developer ID Application” certificate
• $APP_NOTARIZATION_PROFILE - notarization profile in macOS keychain.
  • Created using xcrun notarytool store-credentials
    • Team ID is shown in Apple developer membership details
    • App specific password is created via Apple ID at account.apple.com
  • Can find by searching for notary.tool.saved-creds in keychain, the profile name is the last segment of the account name

See ../test-apps for some samples.