A Dockerfile mode for emacs
(add-to-list 'load-path "/your/path/to/dockerfile-mode/")
(require 'dockerfile-mode)
(add-to-list 'auto-mode-alist '("Dockerfile\\'" . dockerfile-mode))
Adds syntax highlighting as well as the ability to build the image directly (C-c C-b) from the buffer.
You can specify the image name in the file itself by adding a line like this at the top of your Dockerfile.
## -*- docker-image-name: "your-image-name-here" -*-
If you don't, you'll be prompted for an image name each time you build.