# Working with Plugins

version 9.2.0

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

## 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.

Gradle provides core plugins (e.g., `JavaPlugin`, `GroovyPlugin`, `MavenPublishPlugin`, etc.) as part of its distribution, which means they are available with Gradle itself.

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

    plugins {
        id «plugin name»
    }

For example:

build.gradle.kts

    plugins {
        id("java")
    }

build.gradle

    plugins {
        id 'java'
    }

Non-core (community and custom) plugins must be resolved (i.e. located) 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:

build.gradle.kts

    plugins {
        id("com.gradleup.shadow") version "8.3.4"
    }

build.gradle

    plugins {
        id 'com.gradleup.shadow' version '8.3.4'
    }

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

settings.gradle.kts

    pluginManagement {  (1)
        repositories {
            gradlePluginPortal()
        }
    }

settings.gradle

    pluginManagement {  (1)
        repositories {
            gradlePluginPortal()
        }
    }

The location of the plugin could also be an included build or `buildSrc` for example.

## Applying Plugins

Over time, Gradle has introduced several ways to apply plugins, depending on their source and the scope in which they are needed (such as whether they apply to a single project or multiple subprojects).

Let’s take a look at all the available ways a plugin can be applied:

# | 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:

build.gradle.kts

    plugins {
        java
    }

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:

build.gradle.kts

    plugins {
        id("org.springframework.boot") version "3.3.1"
    }

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»` are a string.

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:

settings.gradle.kts

    include("hello-a")
    include("hello-b")
    include("goodbye-c")

build.gradle.kts

    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)
        plugins.apply("java")
    }

    subprojects {
        // Apply the 'java-library' plugin to all subprojects (excluding the root)
        plugins.apply("java-library")
    }

hello-a/build.gradle.kts

    plugins {
        id("com.example.hello")
    }

hello-b/build.gradle.kts

    plugins {
        id("com.example.hello")
    }

goodbye-c/build.gradle.kts

    plugins {
        id("com.example.goodbye")
    }

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:

settings.gradle.kts

    rootProject.name = "multi-project-build"
    include("domain", "infra", "http")

build.gradle.kts

    plugins {
        id("com.gradleup.shadow") version "8.3.4" apply false
        id("io.ratpack.ratpack-java") version "2.0.0-rc-1" apply false
    }

domain/build.gradle.kts

    plugins {
        `java-library`
    }

    dependencies {
        api("javax.measure:unit-api:1.0")
        implementation("tec.units:unit-ri:1.0.3")
    }

infra/build.gradle.kts

    plugins {
        `java-library`
        id("com.gradleup.shadow")
    }

http/build.gradle.kts

    plugins {
        java
        id("io.ratpack.ratpack-java")
    }

    dependencies {
        implementation(project(":domain"))
        implementation(project(":infra"))
        implementation(ratpack.dependency("dropwizard-metrics"))
    }

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":

buildSrc/build.gradle.kts

    plugins {
        `java-gradle-plugin`
    }

    gradlePlugin {
        plugins {
            create("myPlugins") {
                id = "my-plugin"
                implementationClass = "my.MyPlugin"
            }
        }
    }

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:

build.gradle.kts

    plugins {
        id("my-plugin")
    }

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:

build.gradle.kts

    import org.yaml.snakeyaml.Yaml
    import java.io.File

    buildscript {
        repositories {
            maven {
                url = uri("https://plugins.gradle.org/m2/")
            }
            mavenCentral()  // Where to find the plugin
        }
        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
    val yamlContent = """
            name: Project
        """.trimIndent()
    val yaml = Yaml()
    val data: Map<String, Any> = yaml.load(yamlContent)

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:

build.gradle.kts

    class MyPlugin : Plugin<Project> {
        override fun apply(project: Project) {
            println("Plugin ${this.javaClass.simpleName} applied on ${project.name}")
        }
    }

    apply<MyPlugin>()

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:

settings.gradle.kts

    pluginManagement {
        plugins {
        }
        resolutionStrategy {
        }
        repositories {
        }
    }
    rootProject.name = "plugin-management"

settings.gradle

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

The block can also be used in Initialization Script:

init.gradle.kts

    settingsEvaluated {
        pluginManagement {
            plugins {
            }
            resolutionStrategy {
            }
            repositories {
            }
        }
    }

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{}`:

settings.gradle.kts

    pluginManagement {
        repositories {
            maven(url = file("./maven-repo"))
            gradlePluginPortal()
            ivy(url = file("./ivy-repo"))
        }
    }

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`:

settings.gradle.kts

    pluginManagement {
      val helloPluginVersion: String by settings
      plugins {
        id("com.example.hello") version "${helloPluginVersion}"
      }
    }

build.gradle.kts

    plugins {
        id("com.example.hello")
    }

gradle.properties

    helloPluginVersion=1.0.0

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:

settings.gradle.kts

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

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.

build.gradle.kts

    plugins {
        `java-gradle-plugin`
        `maven-publish`
        `ivy-publish`
    }

    group = "com.example"
    version = "1.0.0"

    gradlePlugin {
        plugins {
            create("hello") {
                id = "com.example.hello"
                implementationClass = "com.example.hello.HelloPlugin"
            }
            create("goodbye") {
                id = "com.example.goodbye"
                implementationClass = "com.example.goodbye.GoodbyePlugin"
            }
        }
    }

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

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):

## 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.

build.gradle.kts

    apply(plugin = "java")

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:

build.gradle.kts

    apply<JavaPlugin>()

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, one needs to append the `::class` suffix to identify a class literal in Kotlin instead of `.class` in Java.

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:

build.gradle.kts

    apply(from = "other.gradle.kts")

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:

libs.versions.toml

    [versions]
    groovy = "3.0.5"
    checkstyle = "8.37"

    [libraries]
    groovy-core = { module = "org.codehaus.groovy:groovy", version.ref = "groovy" }
    groovy-json = { module = "org.codehaus.groovy:groovy-json", version.ref = "groovy" }
    groovy-nio = { module = "org.codehaus.groovy:groovy-nio", version.ref = "groovy" }
    commons-lang3 = { group = "org.apache.commons", name = "commons-lang3", version = { strictly = "[3.8, 4.0[", prefer="3.9" } }

    [bundles]
    groovy = ["groovy-core", "groovy-json", "groovy-nio"]

    [plugins]
    versions = { id = "com.github.ben-manes.versions", version = "0.45.0" }

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

build.gradle.kts

    plugins {
        `java-library`
        alias(libs.plugins.versions)
    }

build.gradle

    plugins {
        id 'java-library'
        alias(libs.plugins.versions)
    }

| Gradle generates type safe accessors for catalog items.

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