RFE: Gradle support

[vorburger]

This S2I Builder image IMHO really should ("out of the box") support Gradle in addition to Maven.

We can take (strong) inspiration from the following "prior art" work done to implement this here:

• https://developers.redhat.com/blog/2018/12/18/openshift-java-s2i-builder-java-11-grade/
• add support for Gradle builds in addition to Maven fabric8io-images/s2i#118
• add Gradle build support, initial version (fixes #118) fabric8io-images/s2i#121
• add java/examples/gradle and cover it in test.sh (#118) fabric8io-images/s2i#151
• https://github.com/fabric8io-images/s2i/pull/158/files
• add support for incremental Gradle builds fabric8io-images/s2i#150 (still TBD)
• build.gradle ignored during build process. fabric8io-images/s2i#161 (example end-user interest)

[vorburger]

@jmtd before I may sink any time into working on this, I would like to "officially" propose Gradle support, for the product images, not just the community edition. What would be the appropriate issue tracker to start a discussion about that?

[jmtd]

The best answer would be a JIRA issue in the jboss.org JIRA, CLOUD project, "Java S2I" component at the moment. We haven't migrated out of that project even though Cloud Enablement has closed down, so there isn't a better answer yet. And yes please, that would be good to do; I'm nervous about even reviewing or merging Gradle support at this point in time due to not being able to gauge the business interest against the costs involved.

[jmtd]

Just FYI, my current TODO priorities are: Openshift-Next (OCP specifically) support and RHEL8 base image support. Just behind those are community image matters.

[vorburger]

https://issues.jboss.org/browse/CLOUD-3107

[jmtd]

I don't plan to work on this. If someone wants to step up and do it, re-open this issue so we can discuss it. Thanks!