To comply with [Docker best practices][dbp], we are using the [Hadolint][hadolint] tool to analyse each `Dockerfile` .
## Installation
There is a specific `make` target to install the linter.
By default `hadolint` will be installed in `${HOME}/hadolint`.
```bash
$ make lint-install
# Installing hadolint at /Users/romain/hadolint ...
# Installation done!
# Haskell Dockerfile Linter v1.17.6-0-gc918759
```
## Lint
### Per Stack
The linter can be run per stack.
```bash
$ make lint/scipy-notebook
# Linting Dockerfiles in scipy-notebook...
# scipy-notebook/Dockerfile:4 DL3006 Always tag the version of an image explicitly
# scipy-notebook/Dockerfile:11 DL3008 Pin versions in apt get install. Instead of `apt-get install <package>` use `apt-get install <package>=<version>`
# scipy-notebook/Dockerfile:18 SC2086 Double quote to prevent globbing and word splitting.
# scipy-notebook/Dockerfile:68 SC2086 Double quote to prevent globbing and word splitting.
# scipy-notebook/Dockerfile:68 DL3003 Use WORKDIR to switch to a directory
# scipy-notebook/Dockerfile:79 SC2086 Double quote to prevent globbing and word splitting.
# make: *** [lint/scipy-notebook] Error 1
```
Optionally you can pass arguments to the linter.
```bash
# Use a different export format
$ make lint/scipy-notebook ARGS="--format codeclimate"
```
### All the Stacks
The linter can be run against all the stacks.
```bash
$ make lint-all
```
## Ignoring Rules
Sometimes it is necessary to ignore [some rules][rules].
The following rules are ignored by default and sor for all images in the `.hadolint.yaml` file.
-[`DL3006`][DL3006]: We use a specific policy to manage image tags.
-`base-notebook``FROM` clause is fixed but based on an argument (`ARG`).
- Building downstream images from (`FROM`) the latest is done on purpose.
-[`DL3008`][DL3008]: System packages are always updated (`apt-get`) to the latest version.
For other rules, the preferred way to do it is to flag ignored rules in the `Dockerfile`.
> It is also possible to ignore rules by using a special comment directly above the Dockerfile instruction you want to make an exception for. Ignore rule comments look like `# hadolint ignore=DL3001,SC1081`. For example:
