Removal of JDK17 (aka "Require Java 21 or newer") in Jenkins Core

[Damien Duportal]

I'm forking from https://groups.google.com/g/jenkinsci-dev/c/SNsd_pLk4-k/m/jQDOF-3jCgAJ as it is a distinct topic than the LTS backports for 2.541.1.

Context: With https://github.com/jenkinsci/jenkins/pull/26018, we've officially started to drop support of JDK17 (e.g. requiring JDK21) to run Jenkins Core.

It follows the "2+2+2" Java Support Plan described in https://www.jenkins.io/blog/2023/11/06/introducing-2-2-2-java-support-plan/.

This change has been released with 2.545: https://www.jenkins.io/changelog/2.545/.

But it had side effects:

• There are Docker tags for the 2.545 with jdk17: it should not and requires a fix.
• The packaging on some Linux platforms seems to have dependency issues with JDK17/21/other JDK: https://github.com/jenkinsci/packaging/issues/729

I'm opening this email thread to have a centralized discussion and tracking of fixes (so we won't do the same mistakes when we'll drop JDK21).

[Damien Duportal]

About the 2.545 weekly release with the broken packages: As discussed in Matrix (jenkinsci/release), Hervé Le Meur and I are currently pairing to issue a new set of fixed packages and we'll remove the Docker container tags with "jdk17" in it.

As pointed by Tim Jacomb, re-issuing packaging should be faster than triggering a new 2.546 (since the correct Docker containers with JDK21 do NOT need any changes).

[Damien Duportal]

The 2.545 packages have been fixed (see details in https://github.com/jenkinsci/packaging/issues/729) and we are cleaning things up to ensure 2.546 has no issues with the JDK17 removal.

In addition: reminder that the LTS line 2.541.x should NOT have the JDK17 removal. I believe the jenkins/jenkins (Jenkins Core code) is being worked on by Mark, Kris, Alex, Uli and others to ensure that the branch "stable-2.541" has the proper commits.
On the packaging/infra side, Hervé Le Meur and I are ensuring that our backports will also provide the JDK17 packaging.


Please raise your voice if I misunderstood/mistook anything, or if you disagree of course :)

Thanks all for your hard work!

[Damien Duportal]

Another unforeseen consequence of the JDK17 removal in the weekly line: https://github.com/jenkinsci/jenkins/issues/26093#issuecomment-3728594203