Pre-commit

pre-commit is a tool to check formatting, obvious syntax error, etc before code it committed to git repo. This tool helps us from paying attention to those small errors.

The tool itself is written in python. To install the tool, do

1. pip install pre-commit
2. Go to the root of your repo, run pre-commit install

Then you should create a file .pre-commit-config.yml in the root of the repo. This file defines the hooks to be run for this repo.

The first time you add pre-commit, you may want to run pre-commit run -a to run the hooks for all files in your repo. Later it will be automatically run on each commit.

hooks

pre-commit-hooks

pre-commit-hooks are offical hooks. The config I am using looks like this:

---
repos:
  - repo: https://github.com/pre-commit/pre-commit-hooks
    rev: v4.1.0 # last version to support py36
    hooks:
      - id: check-json
      - id: check-toml
      - id: check-yaml
      - id: end-of-file-fixer
        exclude: .(svg|ipynb)$
      - id: fix-encoding-pragma
        args: [--remove]
      - id: no-commit-to-branch
        args: [--branch, develop, --branch, master, --pattern, release/.*]
      - id: pretty-format-json
        args: [--autofix]
      - id: trailing-whitespace
        args: [--markdown-linebreak-ext=md]

The one I like most in this hook is the no-merge-to-branch, save me a many times to reset my develop or master branch. Note, the check-yaml file will have trouble processing .gitlab-ci.yml, it’s better to exclude it. You can ignore it by adding exclude: ^\.gitlab-ci.yml.

black and isort

  - repo: https://github.com/psf/black
    rev: 22.3.0       # this should be the same with plaster dependency
    hooks:
      - id: black
  - repo: https://github.com/pycqa/isort
    rev: 5.10.1
    hooks:
      - id: isort
        name: isort (python)
        args: [--profile, black]
      - id: isort
        name: isort (cython)
        types: [cython]
        args: [--profile, black]
      - id: isort
        name: isort (pyi)
        types: [pyi]
        args: [--profile, black]

Those 2 hooks are python specific. Black is a widely used python formatter. It makes the code base much easier to read. isort sort python imports. Make the imports much organized and everything easier to find.

markdown-toc

  - repo: https://github.com/qiaouchicago/markdown-toc
    rev: 0.1.0
    hooks:
      - id: markdown-toc

I have forked markdown-github-bear-toc and created this hook. It will automatically generate table of contents for markdown files. (I probably should use this for my posts one day)

yaml format and toml sort

  - repo: https://github.com/jumanjihouse/pre-commit-hook-yamlfmt
    rev: 0.2.1
    hooks:
      - id: yamlfmt
        args: [--mapping, '2', --sequence, '4', --offset, '2', --width, '80']
  - repo: https://github.com/pappasam/toml-sort
    rev: v0.19.0 # last version to support py36
    hooks:
      - id: toml-sort
        args: [--in-place]

As their name indicates, those two hook will format and sort yaml and toml file.

detect-secrets

  - repo: git@github.com:Yelp/detect-secrets
    rev: v1.2.0
    hooks:
      - id: detect-secrets
        args: [--baseline, .secrets.baseline]

detect-secrets helps to make sure you do not accidentally commit your passwords, secret tokens to your repo, causing a secure breach.

To create a baseline run:

detect-secrets scan > .secrets.baseline

To update a baseline file, run:

detect-secrets scan --update .secrets.baseline

To audit your baseline file (check whehter any secrete is staged), run:

detect-secrets audit .secrets.baseline

–exclude-secretes

A useful flag from detect-secretes is --exclude-secretes.

Sometimes, you want to be able to ignore certain secret values in your scan. You can specify a regex rule as such:

$ detect-secrets scan --exclude-secrets '(fakesecret|\${.*})'

Or you can specify multiple regex rules as such:

$ detect-secrets scan --exclude-secrets 'fakesecret' --exclude-secrets '\${.*})'

There are many more hooks yet to discover, hope you enjoy your journy!