Gradle Application Plugin
External
Internal
Overview
The application plugin facilitates creating an executable JVM application. It bundles all application JARS, transitive dependencies and operating system specific scripts into a TAR or ZIP file, and it also generates the bash and Windows wrapper scripts to run the application with. The plugin also allows executing the application from the project's work area with the "run" task.
Typical Setup
This setup describes configuration of a multi-project build, whose sub-project create various components of the application and the top level project bundles all those in a distributable artifact. The dependencies between the sub-projects must be configured in the corresponding build.gradle files. To build the application artifact, we assume that there's a sub-project that contains the "main()" static method that triggers the execution, that method exists in "io.example.Main" class, and the sub-project in question is named "main".
As such, the top-level project build.gradle should contain the following relevant configuration:
...
apply plugin: 'application'
mainClassName = "io.example.Main"
dependencies {
...
implementation project(':main')
}
Provided that the rest of the dependencies between sub-projects are correctly declared in the corresponding build.gradle files, the execution of
gradle distZip
will compile everything and will create a ./build/distributions/<rootProject.name>.zip file. The file includes the sub-project artifacts, their transitive dependencies, and wrapper scripts for bash and Windows.
For more details about rootProject.name, see:
Properties
mainClassName
mainClassName = 'greeter.Greeter'
Executing the Application from Project Work Area
gradle run
However, if the application requires command line parameters, they are not propagated. TODO: find a solution. A temporary solution is to unzip the application ZIP in a temp directory and then repeatedly overwrite the relevant JARs
Start Script Customization
This section explains the mechanics behind creating the application start (wrapper) script and shows how the process can be customized: use a different template, create multiple scripts, etc.
Start Script Mechanics
The Application plugin generates by default Unix and Windows start scripts that are capable launching a configured "main" class in an environment where the classpath is correctly set. The default script templates are based on the same scripts used to launch Gradle, which ship as part of the Gradle distribution. The start scripts are completely customizable though. The Application plugin adds a task named "startScripts" to the project's task list. The task can be view with:
gradle tasks --all