¬ just serendipity 🍀 (not just serendipity)

When using pre-commit.com, in an ideal world, every formatter / linter / code analyzer would have a .pre-commit-config.yaml file in its repository root.

In the real world, that’s not always the case.

A recent example: cloudflare/pint:

Prometheus rule linter/validator

It is a golang binary that lints prometheus rules.

Can we bridge the gap?

The end goal is the ability to run pre-commit run --all-files pint in our git repository.

For that, we’ll need to define a local / custom hook in our ~/.pre-commit-config.yaml:

repos:
  - repo: local
    hooks:
      - id: pint
        name: Validate prometheus rules with pint
        language: golang
        additional_dependencies:
          - github.com/cloudflare/pint/cmd/pint@v0.69.1
        entry: pint --offline lint
        types:
          - yaml
        files: ^helm/clustermon-alerts/rules/

That simply works™. How did I get there? Starting with the references:

1. https://adamj.eu/tech/2023/02/09/pre-commit-hooks-unsupported-tools/
2. https://perrotta.dev/2024/11/pre-commit-additional-dependencies-in-golang/
3. https://stackoverflow.com/questions/62974985/go-module-latest-found-but-does-not-contain-package
4. https://pkg.go.dev/github.com/cloudflare/pint@v0.69.1/cmd/pint

The key part is language: golang + additional_dependencies.

Specifying additional_dependencies is a bit tricky. Initially, I did:

github.com/cloudflare/pint@v0.69.1

…but that yields nothing. In fact:

% go run github.com/cloudflare/pint@v0.69.1
go: github.com/cloudflare/pint@v0.69.1: module github.com/cloudflare/pint@v0.69.1 found, but does not contain package github.com/cloudflare/pint

We must always specify the module that contains the main function with go run, and that is cmd/pint.