How to create executable JAR from single Groovy script

Groovy scripts are nice - they allow to use dependencies and write logic in small single file, but Groovy is mostly available on developers machine, but not on servers, so deploying them is a little more tricky. You can package them in uberjar with Gradle, but it requires additional build file and compatible structure, so it is more like project than script already.

To keep things simple, I have created Groovy script that converts other Groovy scripts into executable JARs. It packages all dependencies from Grab and compiles original script into Java main class with same name as script and sets it in manifest. So it is perfectly usable from empty JVM. JAR structure is also compatible with AWS lambda, so it can be launched from there too, just put logic in specific method. To convert your script, just download it from here and run like:

./scriptjar.groovy input.groovy output.jar

Script tries to find groovy libs via GROOVY_HOME, so set it or just hack it for your location, it is just one small Groovy script.

Setting different JAVA_HOME for Gradle in IntelliJ IDEA

There are a lot of different options to set JDK folder in Gradle, but in IntelliJ the only option that worked for me was adding this line:

gradle.java.home=C:/Program Files/Java/jdk1.8.0/

into idea.properties file.

Hosting Ivy or Maven repository on Github with Gradle

If you don't have access to any public repo, but want to host libraries - then Github can be a solution.
Unfortunately, it does not provide proper interfaces for the client applications, but this is still possible.

Lets say that local root folder of your git project is /test.
First, you need to create all necessary poms and jars. To do it, you have to add this to your build.gradle file:

uploadArchives {
  repositories {
    mavenDeployer {
      repository(url: "file:///test/repo")
    }
  }
}

URL property is for proper Maven repository - for now unfortunately, Github is not, so you will have to enter some local folder. After this is added, run Gradle task uploadArchives, then commit and push all output files with git.

Unfortunately, this is not all, as SHA signature is wrong, because your git URL is not same as local. So you will need to find out proper SHA, and until you want to calculate it yourself, one easy way to do it is find some talkative Maven client, for example Grape. Luckily it is part of normal Groovy installation.

Then, you need to add new repo into Grape configuration, open ${user.home}/.groovy/grapeConfig.xml file and add your new repo like

<ibiblio name="myrepo" root="https://raw.github.com/me/mymodule/master/repo" m2compatible="true"/>

And, to get dependencies, just run Grape in verbose mode, for example like:

grape -V install my.group mymodule 0.1

It will fail, but you will get one great error message like:

...-0.1.pom: invalid sha1: expected=7f1089041d63ce7eaa5d6a35ddda3aaa606042e3 computed=8a941ef40645d449b0740023624c2f8b67b84c59 (516ms)

8a941ef40645d449b0740023624c2f8b67b84c59 is what we were looking for.
Just find file whose signature was incorrect, for example for pom it can be mymodule.pom.sha1, update it with new signature and push into git.

That is all, you have new great Maven repository with root under https://raw.github.com/me/mymodule/master/repo.