Kotlin/Native Gradle plugin

Note: The plugin DSL was changed in v0.3.4. See the details below.

Overview

You may use the Gradle plugin to build Kotlin/Native projects. To use it you need to include the following snippet in a build script (see projects in samples directory):

buildscript {
   repositories {
       mavenCentral()
       maven {
           url  "https://dl.bintray.com/jetbrains/kotlin-native-dependencies"
       }
   }

   dependencies {
       classpath "org.jetbrains.kotlin:kotlin-native-gradle-plugin:*"
   }
}

apply plugin: 'konan'

The Kotlin/Native plugin depends on org.jetbrains.kotlin:kotlin-gradle-plugin. So if a build contains both these plugins as buildscript dependencies, it's recommended to declare them in the same build.gradle to avoid issues with plugin classpath.

If you already downloaded the compiler manually you may specify the path to its root directory using konan.home project property (e.g. in gradle.properties).

konan.home=/home/user/kotlin-native-0.5

In this case the compiler will not be downloaded by the plugin.

Building artifacts

The Kotlin/Native Gradle plugin allows one to build artifacts of the following types:

Executable
KLibrary - a library used by Kotlin/Native compiler (*.klib)
Interoperability library - a special type of library providing an interoperability with some native API. See INTEROP.md for details
Dynamic library (*.so/*.dylib/*.dll)
Objective-C framework
LLVM bitcode

All Kotlin/Native artifacts should be declared in the konanArtifacts block. Note that the konanInterop script block was removed in v0.3.4. Use the interop method of the konanArtifact block instead:

konanArtifacts {
    program('foo')  // executable 'foo'
    library('bar')  // library 'bar'
    bitcode('baz')  // bitcode file 'baz'
    interop('qux')  // interoperability library 'qux'. Use it instead of konanInterop block.
    dynamic('quux') // dynamic library
    framework ('quuux') // Objective-C framework
}

All artifacts except interop libraries are built by the Kotlin/Native compiler. Such an artifact may be configured using its script block. Here one can specify source directories, used libraries and compilation flags (see Plugin DSL section for details). The plugin uses src/main/kotlin/ as a default source directory for all compiler artifacts:

konanArtifacts {
    // Build foo.klib
    library('foo') {
        srcDir 'src/foo/kotlin' // Use custom source path
    }

    // Build executable 'bar'
    program('bar') {
        // The default source path is used (src/main/kotlin)

        // Optimize the output code
        enableOptimizations true

        libraries {
            // Use foo.klib as a library
            artifact 'foo'
        }
    }
}

Interop libraries are built using the cinterop tool. They also may have configuration blocks but the options available in these blocks differ from ones available for compiler artifacts. The input for such an artifact is a def-file describing a native API. By default the def-file path is src/main/c_interop/<library-name>.def but it may be changed using the defFile method of the configuration block of an interoperability library:

    konanArtifacts {
        // Interoperability library stdio.klib
        // Use the default def-file path: src/main/c_interop/stdio.def
        interop('stdio')

        // Interoperability library openal.klib
        interop('openal') {
            defFile 'src/openal/openal.def'
        }

        program('main') {
            libraries {
                // Link with stdio.klib
                artifact 'stdio'
            }
        }
    }

Building for different targets

All the artifacts declared in a project may be built for different targets. By default they are built only for host target i.e. a computer used for building. One may change the default target list using the konan.targets project extension:

konan.targets = [ 'linux', 'android_arm64', 'android_arm32' ]

One may specify a custom target set for each particular artifact using targets parameter of an artifact declaration:

konan.targets = [ 'linux', 'android_arm64' ]

konanArtifacts {
    // This artifact has no custom targets and will be built
    // for all the default ones: 'linux', 'android_arm64'
    program('foo') { /* ... */ }

    // This artifact will be built only for Linux and Wasm32
    program('bar', targets: ['linux', 'wasm32']) { /* ... */ }

    // An Objective-C framework cannot be built for Linux and Wasm32 thus
    // these targets will be skipped and the artifact will be built only for iOS
    framework('baz', targets: [ 'linux', 'wasm32', 'iphone' ]) { /* ... */ }
}

The plugin creates tasks to compile each artifact for all targets supported by current host and declared in the konan.targets list. One may perform additional configuration for a target using target method of an artifact configuration block:

konan.targets = [ 'linux', 'macbook', 'wasm32' ]

konanArtifacts {
    program('foo') {
        // This source file is used for all targets
        srcFiles 'common.kt'

        target('linux') {
            // For Linux common.kt and linux.kt will be compiled
            srcFiles 'linux.kt'
        }

        target('macbook') {
            // For MacOS common.kt and macbook.kt will be compiled
            srcFiles 'macbook.kt'
        }

        // Only common.kt will be compiled for wasm32
    }
}

One may access to a task for some target via artifact methods or properties:

// Both of them return a task building artifact 'foo' for MacOS
konanArtifacts.foo.getByTarget("macbook")
konanArtifacts.foo.macbook

Using libraries

One may specify used libraries for artifacts of all types using libraries script block:

program('foo') {
    libraries {
        // configure the libraries used
    }
}

There are several ways to describe a library used by an artifact:

Specify a library file directly. One may specify it using the file method of the libraries script block. All objects accepted by the Project.file method may be passed there:
```
libraries {
    file 'libs/foo.klib'
    files 'lib1.klib', 'lib2.klib'
}
```

Specify a Kotlin/Native artifact object or its name. In this case the plugin automatically chooses a library with correct target and set dependencies between building tasks.

libraries {
    // Artifact object or just its name may be used
    artifact 'foo'
    artifact kotlinArtifacts.bar
    
    // Artifacts from other projects are also allowed
    artifact project(':bazProject'), 'bazLibrary' 

    // Interopability libraries are also allowed
    // Use it instead of the `useInterop` method available in versions before 0.3.4
    artifact 'stdio'
}

Specify a project containing libraries. In this case all libraries built by the project specified will be used:

libraries {
    allLibrariesFrom project(':subproject')

    // If we need only interoperability libraries
    allInteropLibrariesFrom project(':interop')
}

Specify only name of a library. In this case the compiler will look for the library in its repositories.

libraries {
    klib 'foo'
    klibs 'lib1', 'lib2'

    // One may specify additional repositories
    // All objects accepted by the Project.file method may be used here
    useRepo 'build/libraries'
}

Multiplatform build

Kotlin/Native, as well as Kotlin/JVM and Kotlin/JS, supports multiplatform projects. Such a support is included in the Kotlin/Native Gradle plugin by default and there is no need to apply additional plugins to use it. By default multiplatform support is turned off, and could be enabled with the enableMultiplatform DSL method:

apply 'konan'

konanArtifacts {
    program('foo') {
        enableMultiplatform true
    }
}

The Gradle plugin adds an expectedBy dependency configuration that is used to specify a dependency from Kotlin/Native project to a common project:

apply 'konan'

dependencies {
    expectedBy project('commonProject')
}

When a common project is added as an expectedBy dependency, all the artifacts with the multiplatform support enabled will use it's main source set as a common module. One may specify custom source sets for each artifact using the commonSourceSets DSL method. In this case the multiplatform support will be also enabled for this artifact.

konanArtifacts {
    program('foo') {
        commonSourceSets 'customSourceSet', 'anotherCustomSourceSet'
    }
}

See more about multiplatform projects here.

Tasks

The Kotlin/Native plugin creates the following tasks:

compileKonan<ArtifactName><Target>. The plugin creates such a task for each target declared in konan.targets list and for each an artifact defined in a konanArtifacts block. Such a task may have different properties depending on the artifact type:

Properties available for a compiler task (executable, library or bitcode building task):

Property	Type	Description
`target`	`String`	Target the artifact is built for. Read only
`artifactName`	`String`	Base name for the output file (without an extension)
`destinationDir`	`File`	Directory to place the output artifact
`artifact`	`File`	The output artifact. Read only
`headerFile`	`File`	The output C header. Only for dynamic libraries, read only
`srcFiles`	`Collection<FileCollection>`	Compiled files
`nativeLibraries`	`Collection<FileCollection>`	*.bc libraries used by the artifact
`linkerOpts`	`List<String>`	Additional options passed to the linker
`enableDebug`	`boolean`	Is the debugging support enabled
`noStdLib`	`boolean`	Is the artifact not linked with stdlib
`noMain`	`boolean`	Is the `main` function provided by a library used
`enableOptimizations`	`boolean`	Are the optimizations enabled
`enableAssertions`	`boolean`	Is the assertion support enabled
`measureTime`	`boolean`	Does the compiler print phase time
`enableMultiplatform`	`boolean`	Is multiplatform support enabled for this artifact
`commonSourceSets`	`Collection<String>`	Names of source sets used as a common module

Properties available for a cinterop task (task building an interoperability library):

Property	Type	Description
`target`	`String`	Target the artfact is built for. Read only.
`artifactName`	`String`	Base name for the output file (without an extension)
`destinationDir`	`File`	Directory to place the output artifact
`artifact`	`File`	The output artifact. Read only.
`defFile`	`File`	Def-file used by the interop
`compilerOpts`	`List<String>`	Additional options passed to clang
`linkerOpts`	`List<String>`	Additional options passed to a linker
`headers`	`Collection<FileCollection>`	Additional headers used for stub generation
`linkFiles`	`Collection<FileCollection>`	Additional files linked with the stubs

compileKonan<ArtifactName>. Aggregate task allowing one to build an artifact for several targets. By default it builds the artifact for all supported targets declared for the project. One may change this behavior by specifying the space-separated target list in konan.build.targets project property:
```
./gradlew compileKonanFoo -Pkonan.build.targets='android_arm32 android_arm64'
```
The task has no properties to use by a build script.
compileKonan. Aggregate task to build all the Kotlin/Native artifacts for all available targets. konan.build.targets project property also may be used to override the target list. The task has no properties to use by a build script.
run<ArtifactName>. Such a task is created for each executable supported by current host and allows one to run this executable. The task is an instance of Gradle's Exec so it supports all settings provided by Exec. Additionally, run parameters may be passed to the task using the runArgs project property:
```
./gradlew runFoo -PrunArgs='foo bar'
```

The plugin also edits the default build and clean tasks so that the first one allows one to build all the artifacts supported (it's dependent on the compileKonan task) and the second one removes the files created by the Kotlin/Native build.

Building dynamic libraries and frameworks

Kotlin/Native supports building artifacts to be used by other native languages. There are two types of such artifacts: Objective-C framework and dynamic library.

Dynamic library

A dynamic library may be built using the dynamic artifact block. This block contains the same options as other ones (except interop) allowing one to specify source files, compiler options and libraries used. Each task building a dynamic library produces two files: the library itself (a *.so/*.dylib/*.dll file depending on the target platform) and a C language header. Both of them may be accessed via properties of a building task (both properties have type File):

```
konanArtifacts {
    // Build a dynamic library 
    dynamic('foo') { /* ... */ }
}

konanArtifacts.foo.getByTarget('host').artifact    // Points to the library file
konanArtifacts.foo.getByTarget('host').headerFile  // Points to the header file 
```

Using a dynamic library is shown in the python extension sample.

Framework

An Objective-C framework can be built using the framework artifact block. This block contains the same options as other ones. One may access the framework built using artifact property of the building task (see the Tasks section). Unlike other artifacts this property points to a directory instead of a regular file.

```
konanArtifacts {
    // Build an Objective-C framework
    framework('foo') { /* ... */ }
}

konanArtifacts.foo.getByTarget('host').artifact // Points to the framework directory
```

Using a framework is shown in the calculator sample.

Additional options

You can also pass additional command line keys to the compiler or cinterop tool using the extraOpts expression available in artifact configuration script block. For example this sample enables a verbose output for a link and bitcode generation stages and prints execution time for all compiler phases:

konanArtifacts {
    program('foo') {
        extraOpts '--verbose', 'linker', '--verbose', 'bitcode', '--time'
    }
}

Any command line key supported by the according tool (compiler or cinterop) can be used. Some of them are listed in the tables below.

Compiler additional options

Key	Description
`--disable <Phase>`	Disable backend phase
`--enable <Phase>`	Enable backend phase
`--list_phases`	List all backend phases
`--time`	Report execution time for compiler phases
`--verbose <Phase>`	Trace phase execution
`-verbose`	Enable verbose logging output

Cinterop additional options

Key	Description
`-verbose <boolean>`	Increase verbosity
`-shims <boolean>`	Add generation of shims tracing native library calls

Plugin DSL

// Default targets to build for.
konan.targets = ['macbook', 'linux', 'wasm32']

// Language and API version.
konan.languageVersion = 'version'
konan.apiVersion = 'version'

konanArtifacts {
    // Targets to build this artifact for (optional, override the konan.targets list)
    program('foo', targets: ['android_arm32', 'android_arm64']) {

        // Directory with source files. The default path is src/main/kotlin.
        srcDir 'src/other'

        // Source files.
        srcFiles project.fileTree('src')
        srcFiles 'foo.kt', 'bar.kt'

        // Custom output artifact name (without extension).
        // The default is a name of the artifact
        artifactName 'customName'

        // Base Directory for the output artifacts.
        // Separate subdirectories for each target will be created
        // The default is build/konan/bin
        baseDir 'path/to/output/dir'

        libraries {
            // Library files
            file 'foo.klib'
            files 'file1.klib', file2.klib
            files project.files('file3.klib', 'file4.klib')

            // An artifact from the current project
            artifact konanArtifacts.bar
            artifact 'baz'

            // An artifact from another project
            artifact project(':path:to:a:project'), 'artifcatName'

            // All libraries from anohter project
            allLibrariesFrom project(':some:project')

            // Only interoperability libraries from anohter project
            allInteropLibrariesFrom project(':some:interop:project')

            // Named libraries for search in repositoreis
            klib 'foo'
            klib 'bar', 'baz'

            // Custom repository paths
            useRepo 'path/to/a/repo'
            useRepos 'another/repo/1', 'another/repo/2'

        }

        // A naitve library (*.bc) for linking.
        nativeLibrary project.file('path/to/native/library.bc')
        nativeLibraries 'library1.bc', 'library2.bc'

        noStdLib true             // Don't link with stdlib (true/false).
        enableOptimizations true  // Enable compiler optimizations (true/false).
        enableAssertions true     // Enable assertions in binaries generated (true/false).
        enableDebug true          // Enable debugging for binaries generated (true/false).
        noDefaultLibs true        // Don't link with default libraries

        // Custom entry point
        entryPoint 'org.demo.foo'

        // Arguments to be passed to a linker.
        linkerOpts 'Some linker option', 'More linker options'

        // Print all parameters during the build.
        dumpParameters true

        // Print time of compilation phases (equivalent of the `--time` command line option).
        measureTime true

        // Add the `anotherTask` to the compilation task dependencies.
        dependsOn anotherTask

        // Pass additional command line options to the compiler.
        extraOpts '--time', '--verbose', 'linker'

        // Additional configuration for Linux.
        target('linux') {
            // Exact output directory for a file compile for the given target
            // The default is <baseDir>/<target>
            destinationDir 'exact/output/path'

            // Also all options described for this artifact above are available here.
        }
    }

    library('bar') {
        // Library has the same parameters as an executable
        // The default baseDir is build/konan/libs
    }

    bitcode('baz') {
        // Bitcode has the same parameters as an executable
        // The default baseDir is build/konan/bitcode
    }

    dynamic('quux') {
        // Dynamic library has the same parameters as an executable
        // The default baseDir is build/konan/bin
    }

    framework('quuux') {
        // Framework has the same parameters as an executable
        // The default baseDir is build/konan/bin
    }

    interop('qux') {
        // Def-file describing the native API.
        // The default path is src/main/c_interop/<interop-name>.def
        defFile project.file("deffile.def")

        // Custom output artifact name (without extension).
        // The default is a name of the artifact
        artifactName 'customName'

        // Base Directory for the output artifacts.
        // Separate subdirectories for each target will be created
        // The default is build/konan/libs
        baseDir 'path/to/output/dir'

        // Package to place the Kotlin API generated.
        packageName 'org.sample'

        libraries {
            // All library options from the executable example above are available here.
        }

        // Options to be passed to compiler and linker by cinterop tool.
        compilerOpts 'Options for native stubs compilation'
        linkerOpts 'Options for native stubs'

         // Additional headers to parse.
        headers project.files('header1.h', 'header2.h')

        // Directories to look for headers.
        includeDirs {
            // All objects accepted by the Project.file method may be used with both options.

            // Directories for header search (an analogue of the -I<path> compiler option).
            allHeaders 'path1', 'path2'

            // Additional directories to search headers listed in the 'headerFilter' def-file option.
            // -headerFilterAdditionalSearchPrefix command line option analogue.
            headerFilterOnly 'path1', 'path2'
        }
        // A shortcut for includeDirs.allHeaders.
        includeDirs "include/directory" "another/directory"

        // Additional files to link with native stubs.
        link <files which will be linked with native stubs>

        // Print all parameters during the build.
        dumpParameters true

        // Add the `anotherTask` to the stub generation task dependencies.
        dependsOn anotherTask

        // Pass additional command line options to the cinterop tool.
        extraOpts '-shims', 'true'

        // Additional configuration for Linux.
        target('linux') {
            // Exact output directory for a file compile for the given target
            // The default is <baseDir>/<target>
            destinationDir 'exact/output/path'

            // Also all options described for this artifact above are available here.
        }
    }
}

Multiplatform DSL

apply plugin: 'konan'

// In this example common code is located in 'foo' and 'bar' source sets of ':common' project.

konanArtifacts {
    // All the artifact types except interop libraries may use common modules.
    program('foo') {
        // All artifact settings described above are available here.
        
        // Enable multiplatform support for this artifact.
        enableMultiplatform true
        
        // Set a custom names for source sets used as a common module.
        // The default source set is 'main'
        commonSourceSets 'foo', 'bar'
    }
}

dependencies {
    // Use the ':foo' project as a common project for multiplatform build.
    expectedBy project(':common')
}

Publishing to Maven.

Publishing the Kotlin/Native artifacts depends on mechanisms which was introduced in Gradle Native support, e.g. Gradle's metadata feature, thus there are some additional steps are required. First of all gradle version it shouldn't be less then gradle version of kotlin native plugin depends on (currently Gradle 4.7). before Gradle 5.0 feature GRADLE_METADATA should be enabled for build. e.g. in settings.gradle

enableFeaturePreview('GRADLE_METADATA')

Some maven repositories requires some declarations in pom files, that should be presents in all auxilary pom files ( platform x build types). To meet this requirement the Kotlin/Native plugin has following syntax to do it:

konanArtifacts {
    interop('libcurl') {
        target('linux') {
            includeDirs.headerFilterOnly '/usr/include'
        }
        target('macbook') {
            includeDirs.headerFilterOnly '/opt/local/include', '/usr/local/include'
        }
        pom {
            withXml {
                def root = asNode()
                root.appendNode('name', 'libcurl interop library')
                root.appendNode('description', 'A library providing interoperability with host libcurl')
            }
        }
    }
}

In this example name and description tags will be added to each generated pom file for libcurl published artifact.

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Kotlin/Native Gradle plugin

Note: The plugin DSL was changed in v0.3.4. See the details below.

Overview

Building artifacts

Building for different targets

Using libraries

Multiplatform build

Tasks

Properties available for a compiler task (executable, library or bitcode building task):

Properties available for a cinterop task (task building an interoperability library):

Building dynamic libraries and frameworks

Dynamic library

Framework

Additional options

Compiler additional options

Cinterop additional options

Plugin DSL

Multiplatform DSL

Publishing to Maven.

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Kotlin/Native Gradle plugin

Note: The plugin DSL was changed in v0.3.4. See the details below.

Overview

Building artifacts

Building for different targets

Using libraries

Multiplatform build

Tasks

Properties available for a compiler task (executable, library or bitcode building task):

Properties available for a cinterop task (task building an interoperability library):

Building dynamic libraries and frameworks

Dynamic library

Framework

Additional options

Compiler additional options

Cinterop additional options

Plugin DSL

Multiplatform DSL

Publishing to Maven.