Working again on a docker version of teijenkins, I've decided to base it off the official jenkins:stable image, which in turn inherits from openjdk:jdk-8, which comes ultimately from debian jessie. It's going OK: I have all the required stuff for TEI builds installing correctly, rnv building, and Jenkins running, but I'm failing to pre-install the Jenkins plugins we need right now.
Once you have an instance running, this is how to attach to it and get a shell (assuming the running instance default app is not a shell that you can use, as is the case with a Jenkins server):
sudo docker exec -i -t teijenkins /bin/bash
where "teijenkins" is the name of the running instance, set by using e.g.:
docker run --name teijenkins -p 8080:8080 -p 50000:50000 -v /var/jenkins_home tei-jenkins