How to create the fat jar with gradle kotlin script

Question

As titled, I'd like to know how to modify the gradle.build.kts in order to have a task to create a unique jar with all the dependencies (kotlin lib included) inside.

I found this sample in Groovy:

//create a single Jar with all dependencies
task fatJar(type: Jar) {
    manifest {
        attributes 'Implementation-Title': 'Gradle Jar File Example',
            'Implementation-Version': version,
            'Main-Class': 'com.mkyong.DateUtils'
    }
    baseName = project.name + '-all'
    from { configurations.compile.collect { it.isDirectory() ? it : zipTree(it) } }
    with jar
}

But I have no idea how I could write that in kotlin, other than:

task("fatJar") {

}

Answer 1

Here is a version that does not use a plugin, more like the Groovy version.

import org.gradle.jvm.tasks.Jar

val fatJar = task("fatJar", type = Jar::class) {
    baseName = "${project.name}-fat"
    manifest {
        attributes["Implementation-Title"] = "Gradle Jar File Example"
        attributes["Implementation-Version"] = version
        attributes["Main-Class"] = "com.mkyong.DateUtils"
    }
    from(configurations.runtime.map({ if (it.isDirectory) it else zipTree(it) }))
    with(tasks["jar"] as CopySpec)
}

tasks {
    "build" {
        dependsOn(fatJar)
    }
}

Also explained here

---

Some commenters pointed out that this does not work anymore with newer Gradle versions. Update tested with Gradle 5.4.1:

import org.gradle.jvm.tasks.Jar

val fatJar = task("fatJar", type = Jar::class) {
    baseName = "${project.name}-fat"
    manifest {
        attributes["Implementation-Title"] = "Gradle Jar File Example"
        attributes["Implementation-Version"] = version
        attributes["Main-Class"] = "com.mkyong.DateUtils"
    }
    from(configurations.runtimeClasspath.get().map({ if (it.isDirectory) it else zipTree(it) }))
    with(tasks.jar.get() as CopySpec)
}

tasks {
    "build" {
        dependsOn(fatJar)
    }
}

Note the difference in configurations.runtimeClasspath.get() and with(tasks.jar.get() as CopySpec).

Answer 2

You could use the ShadowJar plugin to build a fat jar:

import com.github.jengelman.gradle.plugins.shadow.tasks.ShadowJar

buildscript {
    repositories {
        mavenCentral()
        gradleScriptKotlin()
    }
    dependencies {
        classpath(kotlinModule("gradle-plugin"))
        classpath("com.github.jengelman.gradle.plugins:shadow:1.2.3")
    }
}

apply {
    plugin("kotlin")
    plugin("com.github.johnrengelman.shadow")
}

repositories {
    mavenCentral()
}

val shadowJar: ShadowJar by tasks
shadowJar.apply {
    manifest.attributes.apply {
        put("Implementation-Title", "Gradle Jar File Example")
        put("Implementation-Version" version)
        put("Main-Class", "com.mkyong.DateUtils")
    }

    baseName = project.name + "-all"
}

Simply run the task with 'shadowJar'.

NOTE: This assumes you're using GSK 0.7.0 (latest as of 02/13/2017).