# Using Plugins

version 8.9

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. Local plugins - Gradle enables users to create custom plugins using APIs.

## Types of plugins

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

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.

Precompiled Script Plugins

  Precompiled script plugins are Groovy DSL or Kotlin DSL scripts compiled and distributed as Java class files packaged in a library. They are applied to a project using the `plugins {}` block. They provide a way to reuse complex logic across projects and allow for better organization of build logic.

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 simple to use.

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.

## Resolving 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:

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»
    }

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

settings.gradle

    pluginManagement {
        repositories {
            gradlePluginPortal()
            maven {
                url 'https://maven.example.com/plugins'
            }
        }
    }

There are additional considerations for resolving and applying plugins:

# | To | Use | For example:
--- | --- | --- | ---
1 | Apply a core, community or local plugin to a specific project. | The `plugins` block in the build file |
    plugins {
      id("org.barfuin.gradle.taskinfo") version "2.1.0"
    }
2 | Apply common core, community or local plugin to multiple subprojects. | A build script in the `buildSrc` directory |
    plugins {
        id("org.barfuin.gradle.taskinfo") version "2.1.0"
    }
    repositories {
        mavenCentral()
    }
    dependencies {
        implementation(Libs.Kotlin.coroutines)
    }
3 | Apply a core, community or local plugin needed for the build script itself. | The `buildscript` block in the build file |
    buildscript {
      repositories {
        maven {
          url = uri("https://plugins.gradle.org/m2/")
        }
      }
      dependencies {
        classpath("org.barfuin.gradle.taskinfo:gradle-taskinfo:2.1.0")
      }
    }
    plugins {
      id("org.barfuin.gradle.taskinfo") version "2.1.0"
    }
4 | Apply a local script plugins. | The legacy `apply()` method in the build file |
    apply(plugin = "org.barfuin.gradle.taskinfo")
    apply<MyPlugin>()

## 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("com.jfrog.bintray") version "1.8.5"
    }

build.gradle

    plugins {
        id 'com.jfrog.bintray' version '1.8.5'
    }

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.

#### 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:

build.gradle.kts

    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

build.gradle

    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).

#### Only in build scripts and settings file

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.

#### Applying plugins to all subprojects

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 {
        id("com.example.hello") version "1.0.0" apply false
        id("com.example.goodbye") version "1.0.0" apply false
    }

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 {
        id 'com.example.hello' version '1.0.0' apply false
        id 'com.example.goodbye' version '1.0.0' apply false
    }

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.

## 2. Applying 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'
    }

## 3. Applying plugins using the `buildscript{}` block

The `buildscript` block is used for:

1. global `dependencies` and `repositories` required for building the project (applied in the subprojects).

2. declaring which plugins are available for use in the build script (in the `build.gradle(.kts)` file itself).

So when you want to use a library in the build script itself, you must add this library on the script classpath using `buildScript`:

    import org.apache.commons.codec.binary.Base64

    buildscript {
        repositories {  // this is where the plugins are located
            mavenCentral()
            google()
        }
        dependencies { // these are the plugins that can be used in subprojects or in the build file itself
            classpath group: 'commons-codec', name: 'commons-codec', version: '1.2' // used in the task below
            classpath 'com.android.tools.build:gradle:4.1.0' // used in subproject
        }
    }

    tasks.register('encode') {
        doLast {
            def byte[] encodedString = new Base64().encode('hello world\n'.getBytes())
            println new String(encodedString)
        }
    }

And you can apply the globally declared dependencies in the subproject that needs it:

    plugins {
        id 'com.android.application'
    }

Binary plugins published as external jar files can be added to a project by adding the plugin to the build script classpath and then applying the plugin.

External jars can be added to the build script classpath using the `buildscript{}` block as described in External dependencies for the build script:

build.gradle.kts

    buildscript {
        repositories {
            gradlePluginPortal()
        }
        dependencies {
            classpath("com.jfrog.bintray.gradle:gradle-bintray-plugin:1.8.5")
        }
    }

    apply(plugin = "com.jfrog.bintray")

build.gradle

    buildscript {
        repositories {
            gradlePluginPortal()
        }
        dependencies {
            classpath 'com.jfrog.bintray.gradle:gradle-bintray-plugin:1.8.5'
        }
    }

    apply plugin: 'com.jfrog.bintray'

## 4. 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:

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

    apply<MyPlugin>()

Let’s take a rudimentary example of a plugin written in a file called `other.gradle` located in the same directory as the `build.gradle` file:

    public class Other implements Plugin<Project> {
        @Override
        void apply(Project project) {
            // Does something
        }
    }

First, import the external file using:

    apply from: 'other.gradle'

Then you can apply it:

    apply plugin: Other

Script plugins are automatically resolved and can be applied from a script on the local filesystem or remotely:

build.gradle.kts

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

build.gradle

    apply from: 'other.gradle'

Filesystem locations are relative to the project directory, while remote script locations are specified with an HTTP URL. Multiple script plugins (of either form) can be applied to a given target.

## 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 = "./maven-repo")
            gradlePluginPortal()
            ivy(url = "./ivy-repo")
        }
    }

settings.gradle

    pluginManagement {
        repositories {
            maven {
                url './maven-repo'
            }
            gradlePluginPortal()
            ivy {
                url './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 './maven-repo'
            }
            gradlePluginPortal()
            ivy {
                url './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.

## 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:

gradle/libs.versions.toml

    [versions]
    intellij-plugin = "1.6"

    [plugins]
    jetbrains-intellij = { id = "org.jetbrains.intellij", version.ref = "intellij-plugin" }

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

build.gradle.kts

    plugins {
        alias(libs.plugins.jetbrains.intellij)
    }

| `jetbrains-intellij` is available as the Gradle generated safe accessor: `jetbrains.intellij`.

Next Step: Learn how to write Plugins >>