A Three-Year Community Pain Point—I Put Hadolint on PyPI, Ending Manual Installation

If you are a developer who pursues code quality, Hadolint must be indispensable in your toolkit. As the benchmark for Dockerfile syntax checking, it helps you write higher-quality Dockerfiles.

However, when integrating into the pre-commit workflow, Hadolint has always had a nagging problem: there is no official, automatically installable binary version for pre-commit to use.

Pain Point Revisited: The Missing “Automation” Last Mile

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If you want to use Hadolint in pre-commit, there are usually only two ways:

1. System Mode: You must first manually download the Hadolint binary and configure environment variables on your Mac/Linux/Windows. If there are 10 people on the team, you’d have to teach all 10 how to install it.
2. Docker Mode: Run via hadolint-docker. But this requires Docker to be installed in the runtime environment, and running Docker containers in a nested fashion in a CI environment (e.g., GitHub Actions) is slow and complex to configure.

This problem has been hanging in the Hadolint GitHub repository for three years Issue #886.

The Breakthrough: Making Hadolint “Disguise” Itself as a Python Package

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My approach was straightforward: since pre-commit has the most perfect support for Python packages, I’ll just give Hadolint a Python shell.

The inspiration came from my previous experience packaging Gnuplot—packaging binary files directly into Python packages and uploading them to PyPI allows pre-commit to install them just like any other Python tool.

Just yesterday, I officially released hadolint-py and hadolint-pre-commit, solving this three-year-old problem. The specific approach consists of three steps:

1. Binary Packaging: Encapsulate Hadolint’s latest native binary into a Python Wheel package and upload it to PyPI.
2. Zero-Dependency Installation: When executing pip install hadolint-py, the Hadolint executable will automatically land in the Python environment’s bin/ directory, ready for direct use.
3. Seamless Integration: For pre-commit, it’s now as simple as calling flake8 or black, no longer requiring any additional software to be pre-installed.

How to Get Started?

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Just add the following configuration to .pre-commit-config.yaml:

repos:
  - repo: https://github.com/shenxianpeng/hadolint-pre-commit
    rev: v2.14.0.1
    hooks:
      - id: hadolint

It’s that simple. Whether for local development or CI pipelines, as long as there’s a Python environment, Hadolint is plug-and-play.

Is This Solution Reliable?

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The “binary to Python package” approach has already been validated by the gnuplot-wheel project, significantly lowering the barrier to entry for tools. hadolint-py continues with the same method, simply swapping out the main character for Hadolint.

• Project Address: hadolint-pre-commit
• PyPI Package: hadolint-py

If you have also been troubled by Hadolint’s installation issues, or are looking for a cleaner Dockerfile Lint solution, feel free to try it out and give it a Star. For any questions or suggestions, please feel free to raise an Issue on GitHub for discussion.