1. Download Kobalt

Download the zip file then unzip it in a location we'll call KOBALT_HOME:

cd $KOBALT_HOME
unzip kobalt-xxx.zip

Note: Kobalt doesn't need any environment variable to run, the environment variable used above is only here for clarity.

2. Initialize your project

Change to your project directory and call the kobaltw command with --init:

cd ~/java/project
$KOBALT_HOME/kobaltw --init

This command will do two things:

1. Create a default kobalt/src/Build.kt file based on what was found in your project.
2. Install the Kobalt Wrapper in your current directory (a script called kobaltw) and a few additional files in the kobalt/wrapper directory. From now on, you can just use ./kobaltw to build and you can ignore $KOBALT_HOME.

You can now attempt to build your project with Kobalt:

./kobaltw assemble

If your project follows a regular build structure (e.g. Maven's hierarchy), this should compile your file and create a .jar file. If not, you will have to make a few edits to your Build.kt. As of this writing, Kobalt supports Java and Kotlin projects.

3. Edit kobalt/src/Build.kt

Here is the Build.kt for the Wasabi HTTP framework:

import com.beust.kobalt.*
import com.beust.kobalt.plugin.packaging.assemble
import com.beust.kobalt.plugin.kotlin.*

val kotlinVersion = "1.0.0-beta-4583"

val p = kotlinProject {

    name = "wasabi"
    group = "com.example"
    artifactId = name
    version = "0.1"

    // Tell Kobalt to also search here for dependencies
    val repos = repos("http://oss.sonatype.org/content/repositories/snapshots") 

    dependencies {
        compile("org.jetbrains.kotlin:kotlin-stdlib:" + kotlinVersion,
            "org.jetbrains.kotlin:kotlin-reflect:" + kotlinVersion,

            "io.netty:netty-all:4.0.31.Final",
            "commons-codec:commons-codec:1.6",
            "commons-logging:commons-logging:1.1.1",
            "joda-time:joda-time:2.3")
    }

    // Test dependencies
    dependenciesTest {
        compile("junit:junit:4.9",
            "org.mockito:mockito-all:1.9.5",
            "org.apache.httpcomponents:httpclient:4.5.1")
    }

    // Tell kobalt to produce a fat jar and also the artifacts required for Maven
    assemble {
        jar {
            fatJar=true
            name = "wasabi-fat-" + version + ".jar"
        }
        mavenJars{
        }
    }
}

4. Sync your build file

If you're using Intellij IDEA, make sure you've installed the Kobalt plugin and then go to Kobalt -> Sync Build File. Once the build file is synchronized, the errors should disappear and you can now use all the regular functions of IDEA on Build.kt just like any other Kotlin files (auto completion, jump to symbol, etc...).

5. Next steps

From this point, you can either learn how to install the Kobalt IDEA plug-in or read Kobalt's documentation.