The library is available on JCenter. Add the following to your Gradle build script to use it.

repositories {
Adding Grolifant as a compile dependency
dependencies {
  compile 'org.ysb33r.gradle:grolifant:0.2'

Distribution Installer

There are quite a number of occasions where it would be useful to download various versions SDK or distributions from a variety of sources and then install them locally without having to affect the environment of a user. The Gradle Wrapper is already a good example of this. Obviously it would be good if one could also utilise otehr solutions that manage distributions and SDKs on a per-user basis such as the excellent SDKMAN!.

The AbstractDistributionInstaller abstract class provides the base for plugin developers to add such functionality to their plugins without too much trouble.

Getting started

class TestInstaller extends AbstractDistributionInstaller {
        static final String DISTPATH = 'foo/bar'
        static final String DISTVER  = '0.1'

        TestInstaller(Project project) {
            super('Test Distribution',DISTVER,DISTPATH,project) (1)

        URI uriFromVersion(String version) { (2)
            TESTDIST_DIR.toURI().resolve("testdist-${DISTVER}.zip") (3)
1 The installer needs to be provided with a human-readable name, the version of the distribution, a relative path below the installation for installing this type of distribution and a reference to an exiting Gradle Project instance.
2 The uriFromVersion method is used to returned an appropriate URI where to download the specific version of distribution from. Supported protocols are all those supported by Gradle Wrapper and includes file, http(s) and ftp.
3 Use code appropriate to your specific distribution to calculate the URI.

The download is invoked by calling the getDistributionRoot method.

The above example uses Groovy to implement an installer class, but you can use Java, Kotlin or any other JVM-language that works for writing Gradle plugins.

How it works

When getDistributionRoot is called, it effectively uses the following logic

File location = locateDistributionInCustomLocation(distributionVersion) (1)

if(location == null && this.sdkManCandidateName)  { (2)
    location = getDistFromSdkMan()

location ?: getDistFromCache() (3)
1 If a custom location location is specified, look there first for the specific version
2 If SDKMAN! has been enabled, look if it has an available distribution.
3 Try to get it from cache. If not in cache try to download it.

Marking files executable

Files in some distributed archives are platform-agnostic and it is necessary to mark specific files as executable after unpacking. The addExecPattern method can be used for this purpose.

TestInstaller installer = new TestInstaller(project)
installer.addExecPattern '**/*.sh' (1)
1 Assuming the TestInstaller from Getting Started, this example will mark all shell files in the distribution as executable once the archive has been unpacked.

Patterns are ANT-style patterns as is common in a number of Gradle APIs.

Search in custom locations

The locateDistributionInCustomLocation method can be used for setting up a search in specific locations.

For example a person implementing a Ceylon language plugin might want to look in the ~/.ceylon folder for an existing installation of a specific version.

This optional implementation is completely left up to the plugin author as it will be very specific to a distribution. The method should return null if nothing was found.

Changing the download and unpack root location

By default downloaded distributons will be placed in a subfolder below the Gradle user home directory as specified during construction time. It is possible, especially for testing purposes, to use a root folder other than Gradle user home by setting the downloadRoot

Utilising SDKMAN!

SDKMAN! is a very useful local SDK installation and management tool and when specific SDKs or distributions are already supported it makes sense to re-use them in order to save on download time.

All that is required is to provide the SDKMAN! candidate name using the setSdkManCandidateName method.

Utilising SDKMAN!
installer.sdkManCandidateName = 'ceylon' (1)
1 Sets the candidate name for a distribution as it will be known to SDKMAN!. In this example the Ceylon language distribution is used.


By default the installer will not check any values, but calling setChecksum will force the installer to perform a check after downloading and before unpacking. It is possible to invoke a behavioural change by overriding verification.

TestInstaller installer = new TestInstaller(project)
installer.checksum = 'b1741e3d2a3f7047d041c79d018cf55286d1168fd6f0533e7fae897478abcdef'  (1)
1 Provide SHA-256 checksum string

Only SHA-256 checksums are supported. if you need something else you will need to override verification and provide your own checksum test.

Advanced: Override unpacking

By default, AbstractDistributionInstaller already knows how to unpack ZIPs and TARs of a varierty of compressions. If something else is required, then the unpack method can be overridden.

Advanced: Override verification

Verification of a downloaded distribution occurs in two parts:

  • If a checksum is supplied, the downloaded archive is validated against the checksum. The standard implementation will only check SHA-256 checksums.

  • The unpacked distribution is then checked for sanity. In the default implementation this is simply to check that only one directory was unpacked below the distribution directory. The latter is effectively just replicating the Gradle Wrapper behaviour.

Once again it is possible to customise this behaviour if your distribution have different needs. In this case there are two protected methods than can be overridden:

  • verifyDownloadChecksum - Override this method to take care of handling checksums. The method, when called, will be passed the URI where the distribution was downlaoded from, the location of the archive on the filesystem and the expected checksum. It is possible to pass null for the latter which means that no checksum is available.

  • getAndVerifyDistributionRoot - This validates the distribution on disk. When called, it is passed the the location where the distribution was unpacked into. The method should return the effective home directory of the distribution.

In the case of getAndVerifyDistributionRoot it can be very confusing sometimes as to what the distDir is and what should be returned. The easiest is to explain this by looking at how Gradle wrappers are stored. For instance for Gradle 3.0 the distDir might be something like ~/.gradle/wrapper/dists/gradle-3.0-bin/2z3tfybitalx2py5dr8rf2mti/ whereas the return directory would be ~/.gradle/wrapper/dists/gradle-3.0-bin/2z3tfybitalx2py5dr8rf2mti/gradle-3.0.

Helper and other protected API methods

  • getProject provides access to the associated Gradle Project object.

  • listDirs provides a listing of directories directly below an unpacked distribution. It can also be used for any directory if the intent is to see which child directories are available.

  • getLogger provides access to a simple stdout logger.

Operating System

Many plugin developers are familiar with the OperatingSystem internal API in Gradle. Unfortunately this remains an internal API and is subject to change.

Grolifant offers a similar public API with a small number of API differences:

  • No getFamilyName and getNativePrefix methods. (A scan of the Gradle 3.2.1 codebase seem to yield to usage either).

  • No public static fields called WINDOWS, MACOSX etc. These are now a static field called INSTANCE on each of the specific operating system implementations.

  • getSharedLibrarySuffix and getSharedLibraryName have been added.

  • Support for NetBSD.


OperatingSystem os = OperatingSystem.current() (1)
    File findExe = os.findInPath('bash')
1 Use current() to the operating system the code is being executed upon.

Operating system detection

The logic in 0.2 to determine an operating system is

static OperatingSystem current() {
    if (OS_NAME.contains("windows")) {
        return Windows.INSTANCE
    } else if (OS_NAME.contains("mac os x") || OS_NAME.contains("darwin") || OS_NAME.contains("osx")) {
        return MacOsX.INSTANCE
    } else if (OS_NAME.contains("linux")) {
        return Linux.INSTANCE
    } else if (OS_NAME.contains("freebsd")) {
        return FreeBSD.INSTANCE
    } else if (OS_NAME.contains("sunos") || OS_NAME.contains("solaris")) {
        return Solaris.INSTANCE
    } else if (OS_NAME.contains("netbsd")) {
        return NetBSD.INSTANCE
    } else {
        // Not strictly true, but a good guess
        return GenericUnix.INSTANCE

Contributing fixes

Found a bug or need a method? Please raise an issue and preferably provide a pull request with features implemented for all supported operating systems.

String Utilities

Converting objects to strings

Use the stringize method to convert nearly anything to a string or a collection of strings. Closures are evaluated and the results are then converted to strings.

StringUtils.stringize( 'foo' )           == 'foo'
StringUtils.stringize( new File('foo') ) == 'foo'
StringUtils.stringize( {'foo'} )         == 'foo'

StringUtils.stringize(['foo1',new File('foo2'),{'foo3'}]) == ['foo1','foo2','foo3']

URI Utilities

Converting objects to URIs

Use the urize method to convert nearly anything to a URI. If objects that have toURI() methods those methods will be called, otherwise objects that are convertible to strings, will effectively call toString().toURI(). Closures will be evaluated and the results are then converted to URIs.

UriUtils.urize( 'ftp://foo/bar' )        == new URI('ftp://foo/bar')
UriUtils.urize( new File('/') )   == new File('/').toURI()
UriUtils.urize( {'ftp://foo/bar'} )      == new URI('ftp://foo/bar')
UriUtils.urize( {new File('/')} ) == new File('/').toURI()

What’s in a name

Grolifant is a concatenation of Gr for Gradle and olifant, which is the Afrikaans word for elephant. The latter is of course the main part of the current Gradle logo.