Replace groovy build-tools (buildSrc) with java

[alpar-t]

We want to have build code implemented in Java to make it easier to maintain.
We can easily mix java and groovy implementations and everything is already set up to do so, so it's already easy to create new classes in Java.
It would also be great to take this opportunity to add tests for the newly written Java code.

The ingredients of a great rewrite:

• the groovy code is removed, the java implementation is actually used by the build
• the java implementation does not use the Groovy SDK ( no groovy imports in Java).
  • note that the "convert to java" option in IDEA does add calls to it
• Existing Groovy tests are also ported to Java
  • when there are no existing tests, new unit and/or integration tests are created. There is a precedent for both. Integration tests use Gradle Test Kit. We should have tests for basic functionality, making sure that the test is up-to-date when the inputs/outputs don't change and in some cases for error conditions.
• follow conventions showcased in Gradle example plugin and detailed in the Gradle user guide: writing custom tasks and writing plugins. Make sure to follow the instructions on making tasks incremental.
• Don't use, and replace the use of project.afterEvaluate in custom task implementations as well as any other configuration logic from the task constructor. The custom task constructor should not reference project. Gradle calls methods annotated with @TaskAction as well as @Input, @Output and the like at execution time rather than configuration time as defined by the
  Gradle build lifecycle.

Here's a list of what is still in Groovy. Note that it goes from simple to complex and there are some inner dependencies :

• stand alone tasks and plugins
  • ConcatFilesTask (convert ConcatFilesTask.groovy to .java #34476, Implement ConcatFilesTask from Groovy to Java issues#34459 #37497)
  • NoticeTask (refactor: convert NoticeTask to java #34769)
  • PluginPropertiesTask Convert PluginPropertiesExtension Groovy to Java #39605
  • PluginPropertiesExtension Convert PluginPropertiesExtension Groovy to Java #39605
  • MavenFilteringHack
  • FileContentsTask (refactor: convert FileContentsTask to Java #34539)
  • DependenciesInfoTask
  • VersionCollection (Implement VersionCollection in Java #34050)
  • MessyTestPlugin ( possibly dead code elastic/x-plugins/issues/724 )
  • EmptyDirTask (convert EmptyDirTask.groovy to .java #34672)
• precommit
  • FilePermissionsTask (convert FilePermissionsTask.groovy to .java #34674)
  • ForbiddenPatternsTask (converting ForbiddenPatternsTask to .java #36194)
  • UpdateShasTask ( Converting DependencyLicensesTask and UpdateShasTask to java #35231 , Converting DependencyLicensesTask and UpdateShasTask to java #41921 )
  • DependencyLicensesTask (Converting DependencyLicensesTask and UpdateShasTask to java #35231 , Converting DependencyLicensesTask and UpdateShasTask to java #41921)
  • PrecommitTasks
• doc
  • RestTestFromSnippetsTaskTests
  • RestTestsFromSnippetsTask
  • DocsTestPlugin
  • SnippetsTask
  • RestTestsFromSnippetsTask
• ant and and fixtures
  • LicenseHeadersTask
  • AntTask
• dependent on the new testclusters implementation
  • AntFixture ( used in multipe build scripts )
  • RestTestPlugin
  • StandaloneRestTestPlugin
  • Fixture
  • RestIntegTestTask
  • [x ]RunTask
  • ClusterConfiguration
  • [x ]NodeInfo
  • ClusterFormationTasks
• vagrant
  • VagrantFixture
  • VagrantLoggerOutputStream
  • VagrantCommandTask
  • VagrantTestPlugin
  • BatsOverVagrantTask
  • TapLoggerOutputStream
  • VagrantPropertiesExtension
• plugins
  • BuildPlugin
  • StandaloneTestPlugin
  • PluginBuildPlugin
  • RestTestPlugin
  • StandaloneRestTestPlugin
  • VagrantSupportPlugin
  • TestWithDependenciesPlugin
• carrotsearch : either push changes upstream or replace with Gradle runner ( Run tests with Gradle test runner instead of randomizedtesting.junit4-ant  #31496 )

[elasticmachine]

Pinging @elastic/es-core-infra

[pt429sy]

Hello, I would like to work on this.

[alpar-t]

Hi @pt429sy that's great ! Feel free to pick a class and open a PR.

[baptistemesta]

just for info, I am working on NoticeTask

[Megamiun]

Doing UpdateShasTask, probably will make a PR tonight.

EDIT: Or tomorrow.

[fabiodrg]

I am interested in giving a try to PluginPropertiesExtension. From my understanding it should be quite straightforward.

[cdschneider]

Going to give ForbiddenPatternsTask a shot, FYI

[GuptaNishant]

I am working on DependenciesInfoTask, will raise a PR later

[akki]

I tried porting vagrant.VagrantPropertiesExtension file to Java but it seems all modules inside vagrant package have to be ported in one go to make it work; Please let me know if this work on VagrantPropertiesExtension can anyhow be used/merged separately, otherwise anybody who aims to port all the other files can feel free to use this patch.

@atorok From what I understand, #34769 can be added against NoticeTask in the first comment.

[paras885]

Going to give MavenFilteringHack a shot, FYI

[alpar-t]

@akki Java code can't reference Groovy classes, but groovy can reference Java, so one has to start with leafs in the dependency tree when porting classes.

[jbonn360]

Hi @atorok, I'd like to work on MavenFilteringHack if no one's working on it

[rh-id]

hello @alpar-t would like to work on AntTask if no one's working on it

[alpar-t]

@mark-vieira where do we stand on the AntTask ?

[mark-vieira]

My preference would be to remove it, and refactor the two remaining subclasses to not rely on Ant. So I'm not sure it's a good candidate for migration right now.

[mrmodise]

@mark-vieira @alpar-t I just pulled the latest code and I see PrecommitTasks is still pending migration. I would like to take it on if its not hanging in the PR state. Thanks

[sachinpaliwal1981]

is there any class pending from the list where work is not in progress already, I would like to contribute.

[mark-vieira]

@sachinpaliwal1981 Both MavenFIlteringHack and NoticeTask are good candiates that have no dependencies on other Groovy code and are mostly a strait conversion to Java.

[MarkRibeiro]

I would like to work on this, where can i start?

[edh-oss]

I'd like to work on the code related to docs, SnippetTask and the related classes.

I have a couple questions:

I've seen both junit and spock used for tests. Is there one test framework that you want to make the standard, or does it not matter?

Is there any documentation that spells out things like "This is what constitutes a valid code snippet", or is the existing implementation effectively the documentation as well?

[mark-vieira]

I've seen both junit and spock used for tests. Is there one test framework that you want to make the standard, or does it not matter?

Yes, we want to prefer Spock going forward.

Is there any documentation that spells out things like "This is what constitutes a valid code snippet", or is the existing implementation effectively the documentation as well?

Yeah, I think we'll have to go off of the existing implementation.

[edh-oss]

I'm having trouble getting Spock tests under build-tools-internal recognized by Gradle. I added details and examples in a comment to issue #78864 , thinking it may be related.

[pugnascotia]

@breskeby am I correct in thinking that this is something that you've been working on?

[breskeby]

@pugnascotia yes there is not much groovy left these days but the stuff that is left is more than just a simple port

[elasticsearchmachine]

Pinging @elastic/es-delivery (Team:Delivery)

[morantaf]

Hey, I'm going to give a go to SnippetsTask