Much of Gradle’s functionality is delivered via plugins, including core plugins distributed with Gradle, third-party plugins, and script plugins defined within builds.

Plugins introduce new tasks (e.g., JavaCompile), domain objects (e.g., SourceSet), conventions (e.g., locating Java source at src/main/java), and extend core or other plugin objects.

Plugins in Gradle are essential for automating common build tasks, integrating with external tools or services, and tailoring the build process to meet specific project needs. They also serve as the primary mechanism for organizing build logic.

Benefits of plugins

Writing many tasks and duplicating configuration blocks in build scripts can get messy. Plugins offer several advantages over adding logic directly to the build script:

  • Promotes Reusability: Reduces the need to duplicate similar logic across projects.

  • Enhances Modularity: Allows for a more modular and organized build script.

  • Encapsulates Logic: Keeps imperative logic separate, enabling more declarative build scripts.

Plugin distribution

You can leverage plugins from Gradle and the Gradle community or create your own.

Plugins are available in three ways:

  1. Core plugins - Gradle develops and maintains a set of Core Plugins.

  2. Community plugins - Gradle plugins shared in a remote repository such as Maven or the Gradle Plugin Portal.

  3. Custom plugins - Gradle enables users to create plugins using APIs.

Types of plugins

Plugins can be implemented as binary plugins, precompiled script plugins, or script plugins:

1. Script Plugins

Script plugins are Groovy DSL or Kotlin DSL scripts that are applied directly to a Gradle build script using the apply from: syntax. They are applied inline within a build script to add functionality or customize the build process. They are not recommended but it’s important to understand how to work:

build.gradle.kts
// Define a plugin
class HelloWorldPlugin : Plugin<Project> {
    override fun apply(project: Project) {
        project.tasks.register("helloWorld") {
            group = "Example"
            description = "Prints 'Hello, World!' to the console"
            doLast {
                println("Hello, World!")
            }
        }
    }
}

// Apply the plugin
apply<HelloWorldPlugin>()

2. Precompiled Script Plugins

Precompiled script plugins are Groovy DSL or Kotlin DSL scripts compiled and distributed as Java class files packaged in some library. They are meant to be consumed as a binary Gradle plugin, so they are applied to a project using the plugins {} block. The plugin ID by which the precompiled script can be referenced is derived from its name and optional package declaration.

plugin/src/main/kotlin/my-plugin.gradle.kts
// This script is automatically exposed to downstream consumers as the `my-plugin` plugin
tasks {
    register("myCopyTask", Copy::class) {
        group = "sample"
        from("build.gradle.kts")
        into("build/copy")
    }
}
consumer/build.gradle.kts
plugins {
    id("my-plugin") version "1.0"
}

3. BuildSrc and Convention Plugins

These are a hybrid of precompiled plugins and binary plugins that provide a way to reuse complex logic across projects and allow for better organization of build logic.

buildSrc/src/main/kotlin/shared-build-conventions.gradle.kts
plugins {
    java
}

repositories {
    mavenCentral()
}

dependencies {
    testImplementation("org.junit.jupiter:junit-jupiter:5.8.1")
    implementation("com.google.guava:guava:30.1.1-jre")
}

tasks.named<Test>("test") {
    useJUnitPlatform()
}

tasks.register<Copy>("backupTestXml") {
    from("build/test-results/test")
    into("/tmp/results/")
    exclude("binary/**")
}
app/build.gradle.kts
plugins {
    application
    id("shared-build-conventions")
}

4. Binary Plugins

Binary plugins are compiled plugins typically written in Java or Kotlin DSL that are packaged as JAR files. They are applied to a project using the plugins {} block. They offer better performance and maintainability compared to script plugins or precompiled script plugins.

plugin/src/main/kotlin/plugin/MyPlugin.kt
class MyPlugin : Plugin<Project> {
    override fun apply(project: Project) {
        project.run {
            tasks {
                register("myCopyTask", Copy::class) {
                    group = "sample"
                    from("build.gradle.kts")
                    into("build/copy")
                }
            }
        }
    }
}
consumer/build.gradle.kts
plugins {
    id("my-plugin") version "1.0"
}

The difference between a binary plugin and a script plugin lies in how they are shared and executed:

  • A binary plugin is compiled into bytecode, and the bytecode is shared.

  • A script plugin is shared as source code, and it is compiled at the time of use.

Binary plugins can be written in any language that produces JVM bytecode, such as Java, Kotlin, or Groovy. In contrast, script plugins can only be written using Kotlin DSL or Groovy DSL.

However, there is also a middle ground: precompiled script plugins. These are written in Kotlin DSL or Groovy DSL, like script plugins, but are compiled into bytecode and shared like binary plugins.

A plugin often starts as a script plugin (because they are easy to write). Then, as the code becomes more valuable, it’s migrated to a binary plugin that can be easily tested and shared between multiple projects or organizations.

Using plugins

To use the build logic encapsulated in a plugin, Gradle needs to perform two steps. First, it needs to resolve the plugin, and then it needs to apply the plugin to the target, usually a Project.

  1. Resolving a plugin means finding the correct version of the JAR that contains a given plugin and adding it to the script classpath. Once a plugin is resolved, its API can be used in a build script. Script plugins are self-resolving in that they are resolved from the specific file path or URL provided when applying them. Core binary plugins provided as part of the Gradle distribution are automatically resolved.

  2. Applying a plugin means executing the plugin’s Plugin.apply(T) on a project.

The plugins DSL is recommended to resolve and apply plugins in one step.

Applying plugins

Gradle provides the core plugins (e.g., JavaPlugin, GroovyPlugin, MavenPublishPlugin, etc.) as part of its distribution, which means they are automatically resolved.

Core plugins are applied in a build script using the plugin name:

plugins {
    id «plugin name»
}

For example:

KotlinGroovy
build.gradle
plugins {
    id 'java'
}

Non-core plugins must be resolved before they can be applied. Non-core plugins are identified by a unique ID and a version in the build file:

plugins {
    id «plugin id» version «plugin version»
}

For example:

KotlinGroovy
build.gradle
plugins {
    id 'com.gradleup.shadow' version '8.3.4'
}

And the location of the plugin must be specified in the settings file:

KotlinGroovy
settings.gradle
pluginManagement {  (1)
    repositories {
        gradlePluginPortal()
    }
}

There are additional considerations for resolving and applying plugins:

# To Use For example:

1

Apply a plugin to a project.

The plugins block in the build file.

 
plugins {
  id("org.barfuin.gradle.taskinfo") version "2.1.0"
}

2

Apply a plugin to multiple projects.

The subprojects or allprojects blocks in the root build file. Not Recommended

 
plugins {
    id("org.barfuin.gradle.taskinfo") version "2.1.0"
}
allprojects {
    apply(plugin = "org.barfuin.gradle.taskinfo")
    repositories {
        mavenCentral()
    }
}

3

Apply a plugin to multiple projects.

The plugins block in the root build file.

 
plugins {
    id("com.gradleup.shadow") version "8.3.4" apply false
    id("io.ratpack.ratpack-java") version "1.8.2" apply false
}

4

Apply a plugin to multiple projects.

A convention plugin in the buildSrc directory. Recommended.

 
plugins {
    id("my-convention.gradle.taskinfo")
}

5

Apply a plugin needed for the build script itself.

The buildscript block in the build file itself. Legacy.

 
buildscript {
  repositories {
    mavenCentral()
  }
  dependencies {
    classpath("org.barfuin.gradle.taskinfo:gradle-taskinfo:2.1.0")
  }
}
apply(plugin = "org.barfuin.gradle.taskinfo")

6

Apply a script plugins.

Applying a plugin when type-safe accessors are not available.

The legacy apply() method in the build file. Not Recommended. Legacy.

 
apply<MyCustomBarfuinTaskInfoPlugin>()

1. Applying plugins using the plugins{} block

The plugin DSL provides a concise and convenient way to declare plugin dependencies.

The plugins block configures an instance of PluginDependenciesSpec:

plugins {
    application                                     // by name
    java                                            // by name
    id("java")                                      // by id - recommended
    id("org.jetbrains.kotlin.jvm") version "1.9.0"  // by id - recommended
}

Core Gradle plugins are unique in that they provide short names, such as java for the core JavaPlugin.

To apply a core plugin, the short name can be used:

KotlinGroovy
build.gradle
plugins {
    id 'java'
}

All other binary plugins must use the fully qualified form of the plugin id (e.g., com.github.foo.bar).

To apply a community plugin from Gradle plugin portal, the fully qualified plugin id, a globally unique identifier, must be used:

KotlinGroovy
build.gradle
plugins {
    id 'org.springframework.boot' version '3.3.1'
}

See PluginDependenciesSpec for more information on using the Plugin DSL.

Limitations of the plugins DSL

The plugins DSL provides a convenient syntax for users and the ability for Gradle to determine which plugins are used quickly. This allows Gradle to:

  • Optimize the loading and reuse of plugin classes.

  • Provide editors with detailed information about the potential properties and values in the build script.

However, the DSL requires that plugins be defined statically.

There are some key differences between the plugins {} block mechanism and the "traditional" apply() method mechanism. There are also some constraints and possible limitations.

The plugins{} block can only be used in a project’s build script build.gradle(.kts) and the settings.gradle(.kts) file. It must appear before any other block. It cannot be used in script plugins or init scripts.

Constrained Syntax

The plugins {} block does not support arbitrary code.

It is constrained to be idempotent (produce the same result every time) and side effect-free (safe for Gradle to execute at any time).

The form is:

plugins {
    id(«plugin id»)                             (1)
    id(«plugin id») version «plugin version»    (2)
}
1 for core Gradle plugins or plugins already available to the build script
2 for binary Gradle plugins that need to be resolved

Where «plugin id» and «plugin version» must be constant, literal strings.

The plugins{} block must also be a top-level statement in the build script. It cannot be nested inside another construct (e.g., an if-statement or for-loop).

2. Applying plugins to all subprojects{} or allprojects{}

Suppose you have a multi-project build, you probably want to apply plugins to some or all of the subprojects in your build but not to the root project.

While the default behavior of the plugins{} block is to immediately resolve and apply the plugins, you can use the apply false syntax to tell Gradle not to apply the plugin to the current project. Then, use the plugins{} block without the version in subprojects' build scripts:

KotlinGroovy
settings.gradle
include 'hello-a'
include 'hello-b'
include 'goodbye-c'
build.gradle
plugins {
    // These plugins are not automatically applied.
    // They can be applied in subprojects as needed (in their respective build files).
    id 'com.example.hello' version '1.0.0' apply false
    id 'com.example.goodbye' version '1.0.0' apply false
}

allprojects {
    // Apply the common 'java' plugin to all projects (including the root)
    apply(plugin: 'java')
}

subprojects {
    // Apply the 'java-library' plugin to all subprojects (excluding the root)
    apply(plugin: 'java-library')
}
hello-a/build.gradle
plugins {
    id 'com.example.hello'
}
hello-b/build.gradle
plugins {
    id 'com.example.hello'
}
goodbye-c/build.gradle
plugins {
    id 'com.example.goodbye'
}

You can also encapsulate the versions of external plugins by composing the build logic using your own convention plugins.

3. Applying plugins declared in the root project

You can apply plugins from the root or parent project in a multi-project build to share common logic and behavior with other projects. The root/parent project is the project at the top of the directory hierarchy.

You should use the plugins {} block because it ensures that the plugin is applied and configured before the project’s evaluation phase. This way, you can safely use type-safe accessors for any model elements introduced by the plugin:

In the root/parent build.gradle(.kts), plugins are declared but not applied (via apply false). This approach, while optional, makes the plugins available to be explicitly applied in specific subprojects. Without apply false, plugins declared in the root project cannot be explicitly applied only to certain subprojects.

apply false is optional. If apply false is not used when declaring plugins in the root build file, those plugins would automatically be applied to the root project.

In the infra subproject, the com.gradleup.shadow plugin, which was made available in the root project, is explicitly applied. The http subproject applies io.ratpack.ratpack-java. The domain subproject does not apply a plugin from the root.

4. Applying convention plugins from the buildSrc directory

buildSrc is an optional directory at the Gradle project root that contains build logic (i.e., plugins) used in building the main project. You can apply plugins that reside in a project’s buildSrc directory as long as they have a defined ID.

The following example shows how to tie the plugin implementation class my.MyPlugin, defined in buildSrc, to the id "my-plugin":

KotlinGroovy
buildSrc/build.gradle
plugins {
    id 'java-gradle-plugin'
}

gradlePlugin {
    plugins {
        myPlugins {
            id = 'my-plugin'
            implementationClass = 'my.MyPlugin'
        }
    }
}

The plugin can then be applied by ID:

KotlinGroovy
build.gradle
plugins {
    id 'my-plugin'
}

5. Applying plugins using the buildscript{} block

To define libraries or plugins used in the build script itself, you can use the buildscript block. The buildscript block is also used for specifying where to find those dependencies.

This approach is less common with newer versions of Gradle, as the plugins {} block simplifies plugin usage. However, buildscript {} may be necessary when dealing with custom or non-standard plugin repositories as well as libraries dependencies:

KotlinGroovy
build.gradle
import org.yaml.snakeyaml.Yaml

buildscript {
    repositories { // Where to find the plugin or library
        maven {
            url = uri("https://plugins.gradle.org/m2/")
        }
        mavenCentral()
    }
    dependencies {
        classpath 'org.yaml:snakeyaml:1.19' // The library's classpath dependency
        classpath 'com.gradleup.shadow:shadow-gradle-plugin:8.3.4' // Plugin dependency for legacy plugin application
    }
}

// Applies legacy Shadow plugin
apply plugin: 'com.gradleup.shadow'

// Uses the library in the build script
def yamlContent = """
        name: Project Name
    """
def yaml = new Yaml()
def data = yaml.load(yamlContent)

6. Applying script plugins using the legacy apply() method

A script plugin is an ad-hoc plugin, typically written and applied in the same build script. It is applied using the legacy application method:

KotlinGroovy
build.gradle
class MyPlugin implements Plugin<Project> {
    @Override
    void apply(Project project) {
        println("Plugin ${this.getClass().getSimpleName()} applied on ${project.name}")
    }
}

apply plugin: MyPlugin

Plugin Management

The pluginManagement{} block is used to configure repositories for plugin resolution and to define version constraints for plugins that are applied in the build scripts.

The pluginManagement{} block can be used in a settings.gradle(.kts) file, where it must be the first block in the file:

KotlinGroovy
settings.gradle
pluginManagement {
    plugins {
    }
    resolutionStrategy {
    }
    repositories {
    }
}
rootProject.name = 'plugin-management'

The block can also be used in Initialization Script:

KotlinGroovy
init.gradle
settingsEvaluated { settings ->
    settings.pluginManagement {
        plugins {
        }
        resolutionStrategy {
        }
        repositories {
        }
    }
}

Custom Plugin Repositories

By default, the plugins{} DSL resolves plugins from the public Gradle Plugin Portal.

Many build authors would also like to resolve plugins from private Maven or Ivy repositories because they contain proprietary implementation details or to have more control over what plugins are available to their builds.

To specify custom plugin repositories, use the repositories{} block inside pluginManagement{}:

KotlinGroovy
settings.gradle
pluginManagement {
    repositories {
        maven {
            url = file('./maven-repo')
        }
        gradlePluginPortal()
        ivy {
            url = file('./ivy-repo')
        }
    }
}

This tells Gradle to first look in the Maven repository at ../maven-repo when resolving plugins and then to check the Gradle Plugin Portal if the plugins are not found in the Maven repository. If you don’t want the Gradle Plugin Portal to be searched, omit the gradlePluginPortal() line. Finally, the Ivy repository at ../ivy-repo will be checked.

Plugin Version Management

A plugins{} block inside pluginManagement{} allows all plugin versions for the build to be defined in a single location. Plugins can then be applied by id to any build script via the plugins{} block.

One benefit of setting plugin versions this way is that the pluginManagement.plugins{} does not have the same constrained syntax as the build script plugins{} block. This allows plugin versions to be taken from gradle.properties, or loaded via another mechanism.

Managing plugin versions via pluginManagement:

KotlinGroovy
settings.gradle
pluginManagement {
  plugins {
        id 'com.example.hello' version "${helloPluginVersion}"
    }
}
build.gradle
plugins {
    id 'com.example.hello'
}
gradle.properties
helloPluginVersion=1.0.0

The plugin version is loaded from gradle.properties and configured in the settings script, allowing the plugin to be added to any project without specifying the version.

Plugin Resolution Rules

Plugin resolution rules allow you to modify plugin requests made in plugins{} blocks, e.g., changing the requested version or explicitly specifying the implementation artifact coordinates.

To add resolution rules, use the resolutionStrategy{} inside the pluginManagement{} block:

KotlinGroovy
settings.gradle
pluginManagement {
    resolutionStrategy {
        eachPlugin {
            if (requested.id.namespace == 'com.example') {
                useModule('com.example:sample-plugins:1.0.0')
            }
        }
    }
    repositories {
        maven {
            url = file('./maven-repo')
        }
        gradlePluginPortal()
        ivy {
            url = file('./ivy-repo')
        }
    }
}

This tells Gradle to use the specified plugin implementation artifact instead of its built-in default mapping from plugin ID to Maven/Ivy coordinates.

Custom Maven and Ivy plugin repositories must contain plugin marker artifacts and the artifacts that implement the plugin. Read Gradle Plugin Development Plugin for more information on publishing plugins to custom repositories.

See PluginManagementSpec for complete documentation for using the pluginManagement{} block.

Plugin Marker Artifacts

Since the plugins{} DSL block only allows for declaring plugins by their globally unique plugin id and version properties, Gradle needs a way to look up the coordinates of the plugin implementation artifact.

To do so, Gradle will look for a Plugin Marker Artifact with the coordinates plugin.id:plugin.id.gradle.plugin:plugin.version. This marker needs to have a dependency on the actual plugin implementation. Publishing these markers is automated by the java-gradle-plugin.

For example, the following complete sample from the sample-plugins project shows how to publish a com.example.hello plugin and a com.example.goodbye plugin to both an Ivy and Maven repository using the combination of the java-gradle-plugin, the maven-publish plugin, and the ivy-publish plugin.

KotlinGroovy
build.gradle
plugins {
    id 'java-gradle-plugin'
    id 'maven-publish'
    id 'ivy-publish'
}

group = 'com.example'
version = '1.0.0'

gradlePlugin {
    plugins {
        hello {
            id = 'com.example.hello'
            implementationClass = 'com.example.hello.HelloPlugin'
        }
        goodbye {
            id = 'com.example.goodbye'
            implementationClass = 'com.example.goodbye.GoodbyePlugin'
        }
    }
}

publishing {
    repositories {
        maven {
            url = layout.buildDirectory.dir('maven-repo')
        }
        ivy {
            url = layout.buildDirectory.dir('ivy-repo')
        }
    }
}

Running gradle publish in the sample directory creates the following Maven repository layout (the Ivy layout is similar):

plugin markers

Legacy Plugin Application

With the introduction of the plugins DSL, users should have little reason to use the legacy method of applying plugins. It is documented here in case a build author cannot use the plugin DSL due to restrictions in how it currently works.

KotlinGroovy
build.gradle
apply plugin: 'java'

Plugins can be applied using a plugin id. In the above case, we are using the short name "java" to apply the JavaPlugin.

Rather than using a plugin id, plugins can also be applied by simply specifying the class of the plugin:

KotlinGroovy
build.gradle
apply plugin: JavaPlugin

The JavaPlugin symbol in the above sample refers to the JavaPlugin. This class does not strictly need to be imported as the org.gradle.api.plugins package is automatically imported in all build scripts (see Default imports).

Furthermore, it is unnecessary to append .class to identify a class literal in Groovy as it is in Java.

You may also see the apply method used to include an entire build file:

KotlinGroovy
build.gradle
apply from: 'other.gradle'

Using a Version Catalog

When a project uses a version catalog, plugins can be referenced via aliases when applied.

Let’s take a look at a simple Version Catalog:

Then a plugin can be applied to any build script using the alias method:

KotlinGroovy
build.gradle
plugins {
    id 'java-library'
    alias(libs.plugins.versions)
}
Gradle generates type safe accessors for catalog items.

Next Step: Learn how to write Plugins >>