The “docker commit …” command, you’ll provide both the image-name (all lowercase) and a TAG name (uppercase allowed). You can be creative in having an naming conversion for you images repositories.
It’s very important to save images after doing the commit. I found out that having an active container would be useless without an image. As far as I know, I haven’t found a way to rebuild an image from an existing container if the image was previously removed.
Max has a full demo, including installing various tools and programs as well as tips on how to minimize the pain.