Hello Gradle

Maven is out, Gradle is in— so I learned recently. Time to take a peek.

First, it needs to be installed. On the Mac, I use sdkman:

curl -s "https://get.sdkman.io" | bash
source "/Users/twiss1/.sdkman/bin/sdkman-init.sh"

Also see the official docs.

sdk list gradle
sdk install gradle 3.4.1
gradle -v

Let’s start with a simple Java “Hello World!” that will be compiled and run by Gradle.

package com.rampmeupscotty.blog;

public class Hello {
 public static void main(String[] args) {
 System.out.println("Hello Gradle");
 }
}

I put this file in myproject/src/main/java/com/rampmeupscotty/blog.

Then I create a file called build.gradle in myproject/app with the following content:

apply plugin: 'java'
apply plugin: 'application'

mainClassName = "com.rampmeupscotty.blog.Hello"

In the myproject directory I can check what tasks are available with:

gradle tasks -all

The relevant ones are build and run. Running gradle -q run should produce:

Hello Gradle

It ‘s only half the fun without Docker. Let’s extend build.gradle a bit:

buildscript {
 repositories {
  jcenter()
 }

 dependencies {
  classpath 'com.bmuschko:gradle-docker-plugin:3.0.6'
 }
}

apply plugin: 'java'
apply plugin: 'application'
apply plugin: 'com.bmuschko.docker-java-application'

mainClassName = 'com.rampmeupscotty.blog.Hello'

docker {
 javaApplication {
  maintainer = 'The Dude "thedude@email.com"'
  tag = 'thedude/gradle-docker:latest'
 }
}

Build the image with gradle dockerBuildImage. After that, run it with:

docker run -ti thedude/gradle-docker

Happy with the result? Push the image to the registry with gradle dockerPushImage. Without any parameters, the official Docker registry will be used.

Done for today!

Ramp Me Up, Scotty!

Hello Gradle