Some of the places that announced the change include:
- Jenkins blog including its RSS feed
- Jenkins LinkedIn account
- Jenkins twitter account
- Jenkins weekly changelog and its RSS feed
- Top level Jenkins page has a rotating announcement that links to the blog post
- Gitter chat channel
The change will also be announced in the Jenkins 2.387.2 changelog and upgrade guide and in the “What’s New in Jenkins 2.387.2” live stream.
I agree that even those channels were probably not enough. This change would have been well suited to appear as a Jenkins admin monitor 3-6 months prior to the change. That would have alerted administrators that the change was coming and given them time to plan for the change.
I’ve seen a suggestion that the Debian packages be signed with multiple keys so that the transition could be easier for administrators. I think that is worth exploring as well. I’m sure there are other ideas that are worth considering as well. Keep the ideas and suggestions coming.