Docker build produces many unnamed images

Hey, so I’m quite new to Docker, hence apologies if this is a bit of a newbie question…

I’ve just build my first app using Docker (python 3 flask web app) and it works great.
However, something I noticed when I ran docker images -a is that even though I ran just one single build command to build one single image altum-platform it seems to have created 11 additional images! One of those is labelled python so I’m assuming that has something to do with my app specifying python3. However the others are all unlabelled. And they all take up a considerable amount of space which is not ideal!

I thought Docker images were all one big self-contained thing? Why then, have I got 11 additional images that have automatically been created when I ran one build command?

just guessings from my side.

you executed the docker build command 11 times. At the first time the image was still small (684 MB is not that small infact) and over time you added more and more to your Dockerfile to let it grow to 1.4 GB.
Probably this also results in a recursive Dockerfile - FROM your own image.

However, to get rid of the images you do not need anymore, you could have a look into docker system prune.