Docker image using alpine linux supporting Oracle Java JRE 8
Built for use with resin.io -- I found that the OpenJDK versions were way too slow.
This is jre only -- to get full jdk, edit the Dockerfile to extract the full tarball in /opt, rather than extracting in /tmp and moving the jre to /opt.
You can find the Docker image at docker.io/dpsmyth/raspberrypi3-alpine-java