OpenJDK has not provided yet a base Alpine image for JDK 11.
And it's not going to happen
https://twitter.com/mreinhold/status/1046862466204950529 (Mark Reinhold is Chief Architect of the Java Platform Group)
It might happen for JDK 12, as written in that tweet, but it's a might.
This means we current cannot upgrade the JDK currently set up from 8 to 11 without more than consistent efforts. And even if we achieve to do it, this is quite out of scope, and dangerous for users, for the Jenkins Project to actually offer an openjdk build on Alpine, given even the official OpenJDK image is not doing it!
This is even more an issue because the JDK release cadence has accelerated. JDK 12 is already coming, and JDK 13 is expected in September 2019 (https://openjdk.java.net/projects/jdk/13/spec/).
- Evergreen should use a platform that makes upgrading the JDK a no-brainer (managing the build of the JDK for Alpine is not the mission of the Jenkins Project)
The new target platform/base image is not defined yet. Some people argue for Debian, some Ubuntu, some Centos/Fedora. There will probably be some discussion about this at some later point.