Intermediate images

Hi,

I’ve been using Docker with two apps (Discourse and my copy of RobotGame.net: http://rg.kodujzklasa.pl) and I’ve come across a weird situation with intermediate, untagged images.

According to the Docker docs (https://docs.docker.com/engine/reference/commandline/images/) these images should “decrease disk usage”… As I understand they work as a sort of “cache” for the docker build command. Well, this is awkward, because it turns out that my four containers, which should take up no more than ~1GB of disk space have their “intermediate” images that sum up to 16GB.

And the thing is that I have no idea how to get rid of them. I’ve tried all the ways you can google up, but it seems that the intermediate images are always marked as being in use, which makes them undeletable.

So, is there a way I can get rid of them? Can I force docker to get rid of them and never create them again?

So far it seems I’d have to start my RobotGame website from scratch, which means losing the results of the last 6 months of robot battles, which I would - of course - like to avoid at all costs…

Any help would be appreciated.