Java

Overview

The Java module manages a JDK installation for your Kannich pipeline. It downloads the requested Java version from Eclipse Temurin automatically, caches it, and makes it available to other modules that need a JDK - most commonly Maven. It supports both amd64 and aarch64 architectures.

Add the module to your .kannichfile.main.kts:

@file:DependsOn("dev.kannich:kannich-java:0.10.0")

You can always find the latest version on the Module Versions page.

Basic Usage

Instantiate Java with the major version number you want. You typically declare it at the top of the pipeline so it can be shared across executions:

import dev.kannich.java.Java
import dev.kannich.stdlib.*
import dev.kannich.tools.*

pipeline {
    val java = Java("21")

    execution("run", "Runs the application") {
        job {
            java.exec("-jar", "app.jar")
        }
    }
}

java.exec() runs the java binary with the given arguments and sets JAVA_HOME automatically before running.

In practice the Java module is most often used as a dependency for other tool modules rather than called directly - for example, Maven requires a Java instance to know which JDK to use. See the Maven module for an example of this.

Getting JAVA_HOME

If you need the path to the JDK installation - for example to pass it to a tool that isn't Java-aware - call getInstallPath():

execution("build", "Builds the project") {
    job {
        val javaHome = java.getInstallPath()
        withEnv("JAVA_HOME" to javaHome) {
            Shell.exec("some_tool")
        }
    }
}