Linting a Dockerfile

Like any other language, Dockerfiles can and should be linted for updated best practices and code quality checks. Docker is no exception to the rule, and good practices are always moving, getting updates, and might also be a little different between communities. In this section, we'll start with a basic Dockerfile found earlier and end up with a fully double-checked linted file.

Getting ready

To step through this recipe, you will need the following:

• A working Docker installation
• An AWS account

How to do it…

Many different linters exist for linting Dockerfiles: Hadolint (http://hadolint.lukasmartinelli.ch/) maybe the most used linter, while Project Atomic's dockerfile_lint project is perhaps the most complete one (https://github.com/projectatomic/dockerfile_lint).

Here's the working Dockerfile from earlier in this book:

FROM debian:stable-slim
RUN apt-get update -y \
    && apt-get install -y apache2 \
    && rm -rf /var/lib/apt
ENTRYPOINT...