I'm still working through the best way to deal with keeping versions up to date. Currently I'm using dockerhub to automatically build the x86 containers. The "latest" tag is built with the "master" branch of the dockerfiles which use version=* while the 1.3.1 tag is built with the 1.3.1 branch which has version=1.3.1. dockerhub will rebuild the images anytime a change is committed to the inid-docker repo
Unfortunately dockerhub doesn't yet have automated builds for RPI images so I have to build/push them manually. I'm investigating CI server options for automating it.
I'll take a look at containers for kstars, but it might be more confusing for users due to file system isolation.