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Using the Gradle plugin

Important

If you are upgrading from 0.10.x to a current release of Dokka, please have a look at our migration guide

Supported versions

Dokka should work on gradle newer than 5.6

Setup

The preferred way is to use plugins block.

build.gradle.kts: 

plugins {
    id("org.jetbrains.dokka") version "1.6.10"
}

repositories {
    mavenCentral()
}

You can also use the legacy plugin application method with buildscript block. Note that by using the buildscript way type-safe accessors are not available in Gradle Kotlin DSL, eg. you'll have to use named<DokkaTask>("dokkaHtml") instead of dokkaHtml:

buildscript {
    dependencies {
        classpath("org.jetbrains.dokka:dokka-gradle-plugin:${dokka_version}")
    }
}

apply(plugin="org.jetbrains.dokka")

The plugin adds dokkaHtml, dokkaJavadoc, dokkaGfm and dokkaJekyll tasks to the project.

Each task corresponds to one output format, so you should run dokkaGfm when you want to have a documentation in GFM format. Output formats are explained in the introduction

If you encounter any problems when migrating from older versions of Dokka, please see the FAQ.

Minimal configuration (with custom output directory only):

Kotlin 

tasks.dokkaHtml.configure {
    outputDirectory.set(buildDir.resolve("dokka"))
}

Groovy 

tasks.named("dokkaHtml") {
    outputDirectory.set(buildDir.resolve("dokka"))
}

Configuration options

Dokka documents single-platform as well as multi-platform projects. Most of the configuration options are set per one source set. The available configuration options for are shown below:

import org.jetbrains.dokka.gradle.DokkaTask

val dokkaHtml by getting(DokkaTask::class) {
    outputDirectory.set(buildDir.resolve("dokka"))

    // Set module name displayed in the final output
    moduleName.set("moduleName")

    // Use default or set to custom path to cache directory
    // to enable package-list caching
    // When this is set to default, caches are stored in $USER_HOME/.cache/dokka
    cacheRoot.set(file("default"))

    // Suppress obvious functions like default toString or equals. Defaults to true
    suppressObviousFunctions.set(false)

    // Suppress all inherited members that were not overriden in a given class. 
    // Eg. using it you can suppress toString or equals functions but you can't suppress componentN or copy on data class. To do that use with suppressObviousFunctions
    // Defaults to false
    suppressInheritedMembers.set(true)

    // Used to prevent resolving package-lists online. When this option is set to true, only local files are resolved  
    offlineMode.set(false)

    dokkaSourceSets {
        configureEach { // Or source set name, for single-platform the default source sets are `main` and `test`

            // Used when configuring source sets manually for declaring which source sets this one depends on
            dependsOn("otherSourceSetName")

            // Used to remove a source set from documentation, test source sets are suppressed by default  
            suppress.set(false)

            // Use to include or exclude non public members 
            includeNonPublic.set(false)

            // Do not output deprecated members. Applies globally, can be overridden by packageOptions
            skipDeprecated.set(false)

            // Emit warnings about not documented members. Applies globally, also can be overridden by packageOptions
            reportUndocumented.set(true)

            // Do not create index pages for empty packages
            skipEmptyPackages.set(true)

            // This name will be shown in the final output
            displayName.set("JVM")

            // Platform used for code analysis. See the "Platforms" section of this readme
            platform.set(org.jetbrains.dokka.Platform.jvm)

            // Property used for manual addition of files to the classpath
            // This property does not override the classpath collected automatically but appends to it
            classpath.from(file("libs/dependency.jar"))

            // List of files with module and package documentation
            // https://kotlinlang.org/docs/reference/kotlin-doc.html#module-and-package-documentation
            includes.from("packages.md", "extra.md")

            // List of files or directories containing sample code (referenced with @sample tags)
            samples.from("samples/basic.kt", "samples/advanced.kt")

            // By default, sourceRoots are taken from Kotlin Plugin and kotlinTasks, following roots will be appended to them
            // Repeat for multiple sourceRoots
            sourceRoots.from(file("src"))

            // Specifies the location of the project source code on the Web.
            // If provided, Dokka generates "source" links for each declaration.
            // Repeat for multiple mappings
            sourceLink {
                // Unix based directory relative path to the root of the project (where you execute gradle respectively). 
                localDirectory.set(file("src/main/kotlin"))

                // URL showing where the source code can be accessed through the web browser
                remoteUrl.set(java.net.URL(
                    "https://github.com/cy6erGn0m/vertx3-lang-kotlin/blob/master/src/main/kotlin"))
                // Suffix which is used to append the line number to the URL. Use #L for GitHub
                remoteLineSuffix.set("#L")
            }

            // Used for linking to JDK documentation
            jdkVersion.set(8)

            // Disable linking to online kotlin-stdlib documentation
            noStdlibLink.set(false)

            // Disable linking to online JDK documentation
            noJdkLink.set(false)

            // Disable linking to online Android documentation (only applicable for Android projects)
            noAndroidSdkLink.set(false)

            // Allows linking to documentation of the project"s dependencies (generated with Javadoc or Dokka)
            // Repeat for multiple links
            externalDocumentationLink {
                // Root URL of the generated documentation to link with. The trailing slash is required!
                url.set(URL("https://example.com/docs/"))

                // If package-list file is located in non-standard location
                // packageListUrl = URL("file:///home/user/localdocs/package-list")
            }

            // Allows to customize documentation generation options on a per-package basis
            // Repeat for multiple packageOptions
            // If multiple packages match the same matchingRegex, the longuest matchingRegex will be used
            perPackageOption {
                // will match kotlin and all sub-packages of it
                matchingRegex.set("kotlin($|\\.).*") 

                // All options are optional
                skipDeprecated.set(false)
                reportUndocumented.set(true) // Emit warnings about not documented members 
                includeNonPublic.set(false)
            }
            // Suppress a package
            perPackageOption {
                matchingRegex.set(""".*\.internal.*""") // will match all .internal packages and sub-packages 
                suppress.set(true)
            }

            // Include generated files in documentation
            // By default Dokka will omit all files in folder named generated that is a child of buildDir
            suppressGeneratedFiles.set(false)
        }
        // Configures a plugin separately from the global configuration
        pluginConfiguration<PluginClass, ConfigurationClass>{
            // values
        }
    }
}

Multiplatform

Dokka supports single-platform and multi-platform projects using source sets abstraction. For most mutli-platform projects you should assume that Dokka's source sets correspond to Kotlin plugin's source sets. All source sets are by default registered and configured automatically although test source sets are suppressed

Kotlin 

kotlin {  // Kotlin Multiplatform plugin configuration
    jvm()
    js("customName")
}

tasks.withType<DokkaTask>().configureEach {
    // custom output directory
    outputDirectory.set(buildDir.resolve("dokka"))

    dokkaSourceSets { 
         named("customNameMain") { // The same name as in Kotlin Multiplatform plugin, so the sources are fetched automatically
            includes.from("packages.md", "extra.md")
            samples.from("samples/basic.kt", "samples/advanced.kt")
        }

        register("differentName") { // Different name, so source roots must be passed explicitly
            displayName.set("JVM")
            platform.set(org.jetbrains.dokka.Platform.jvm)
            sourceRoots.from(kotlin.sourceSets.getByName("jvmMain").kotlin.srcDirs)
            sourceRoots.from(kotlin.sourceSets.getByName("commonMain").kotlin.srcDirs)
        }
    }
}

Note

If you want to share the configuration between source sets, you can use Gradle's configureEach

Applying plugins

Dokka plugin creates Gradle configuration for each output format in the form of dokka${format}Plugin (or dokka${format}PartialPlugin for multi-module tasks) :

dependencies {
    dokkaHtmlPlugin("org.jetbrains.dokka:kotlin-as-java-plugin:1.6.10")
}

You can also create a custom Dokka task and add plugins directly inside:

val customDokkaTask by creating(DokkaTask::class) {
    dependencies {
        plugins("org.jetbrains.dokka:kotlin-as-java-plugin:1.6.10")
    }
}

Important

Please note that dokkaJavadoc task will properly document only single jvm source set

To generate the documentation, use the appropriate dokka${format} Gradle task:

./gradlew dokkaHtml

Some plugins can be configured separately using a plugin class and configuration class. For example:

import org.jetbrains.dokka.base.DokkaBase
import org.jetbrains.dokka.base.DokkaBaseConfiguration

pluginConfiguration<DokkaBase, DokkaBaseConfiguration> {
    customAssets = listOf(file("<path to asset>"))
    customStyleSheets = listOf(file("<path to custom stylesheet>"))
}

Keep in mind, that this only works when using a buildscript (with the configured plugin on classpath) since it is not possible to import plugin's class without it. For example, you can add DokkaBase to gain access to aforementioned configuration:

buildscript {
    dependencies {
        // classpath("<plugin coordinates>:<plugin version>")
        classpath("org.jetbrains.dokka:dokka-base:1.6.10")
    }
}

If you don't want to use a buildscript or use Kotlin version lower than 1.3.50 you can achieve the same behaviour manually: 

pluginsMapConfiguration.set(mapOf("<fully qualified plugin's name>" to """<json configuration>"""))

Android

Important

Make sure you apply Dokka after com.android.library and kotlin-android.

buildscript {
    dependencies {
        classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:${kotlin_version}")
        classpath("org.jetbrains.dokka:dokka-gradle-plugin:${dokka_version}")
    }
}
repositories {
    mavenCentral()
}
apply(plugin= "com.android.library")
apply(plugin= "kotlin-android")
apply(plugin= "org.jetbrains.dokka")

dokkaHtml.configure {
    dokkaSourceSets {
        named("main") {
            noAndroidSdkLink.set(false)
        }   
    }
}

Multi-module projects

For documenting Gradle multi-module projects, you can use dokka${format}MultiModule tasks. Dokka plugin adds dokkaHtmlMultiModule, dokkaGfmMultiModule and dokkaJekyllMultiModule tasks to all Gradle parent projects (all projects that have some child projects) as well as dokkaHtmlPartial, dokkaGfmPartial and dokkaJekyllPartial to all projects that have a parent. If you want eg. to add an external link to some dependency you should do so in respective dokka${format}Partial tasks, or configure them all at once using the subprojects block and configureEach method.

tasks.dokkaHtmlMultiModule.configure {
    outputDirectory.set(buildDir.resolve("dokkaCustomMultiModuleOutput"))
}

DokkaMultiModule depends on all Dokka tasks in the subprojects named dokka${format}Partial, runs them, and creates a top-level page with links to all generated (sub)documentations. It is possible to configure each of them: 

tasks.dokkaHtmlPartial.configure {
    failOnWarning.set(true)
}

Example projects

Please see the Dokka Gradle single module example project or multimodule for an example.

Also see generated documentation in HTML format.