Dockerlint

Linting tool for Dockerfiles based on recommendations from Dockerfile Reference and Best practices for writing Dockerfiles as of Docker 1.6.

Install

With npm just do:

$ [sudo] npm install -g dockerlint

Usage

Once installed it's as easy as:

dockerlint Dockerfile

Which will parse the file and notify you about any actual errors (such an omitted tag when : is set), and warn you about common pitfalls or bad idiom such as the common use case of ADD.

In order to treat warnings as errors, use the -p flag.

Docker image

Alternatively there is a Docker image available.

This image provides a quick and easy way to validate your Dockerfiles, without having to install Node.JS and the dockerlint dependencies on your system.

First fetch the image from the Docker Hub:

docker pull redcoolbeans/dockerlint

You can either run it directly, or use docker-compose.

docker run

For a quick one-off validation:

docker run -it --rm -v "$PWD/Dockerfile":/Dockerfile:ro redcoolbeans/dockerlint

docker-compose

For docker-compose use a docker-compose.yml such as the following:

---
  dockerlint:
    image: redcoolbeans/dockerlint
    volumes:
      - ./Dockerfile:/Dockerfile

Then simply run:

docker-compose up dockerlint

This will validate the Dockerfile in your current directory.

Running from a git clone

If you've cloned this repository, you will need the following prerequisites:

1. make
2. npm
3. coffee

Installing prerequisites on ubuntu:

sudo apt-get update
sudo apt-get install make
sudo apt-get install npm
sudo ln -s /usr/bin/nodejs /usr/bin/node
sudo npm install -g coffee-script

You can run dockerlint with:

make deps # runs npm install
make js && coffee bin/dockerlint.coffee

If you're building on Windows, you'll have to set the path to your make:

npm config set dockerlint:winmake "mingw32-make.exe"

or pass it to every invocation:

npm run build:win --dockerlint:winmake=mingw32-make.exe

Roadmap

• Add support for --version which checks against a specific Docker version
• Refactor code to move the rule specific functions into a Rule class

License

MIT, please see the LICENSE file.

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request