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Pre-Commit

Pre-commit is a framework for managing and maintaining multi-language pre-commit hooks.

Git hook scripts are useful for identifying issues before pushing your code or submitting it to review.

There are hooks for various purposes, such as formatting files, running tests, validating syntax, identifying security flaws, among others.

More Information

Installation​

This guide explains how to install and configure pre-commit so that hooks are applied to all repositories that are cloned or initialized.


Install Pre-Commit​

Using homebrew:

brew install pre-commit

Using conda:

conda install -c conda-forge pre-commit

Create Config File​

Create a .pre-commit-config.yaml file in a directory that is easily accessible.

In this example the user's home directory will be used.

This file must contain a list of repositories and IDs of the hooks you want to use.

The list of repositories and hooks are available at https://pre-commit.com/hooks.html.

As an example, the detect-secrets hook will be used to check if there are any potential secrets that may be leaked in the commit:

.pre-commit-config.yaml
repos:
- repo: https://github.com/Yelp/detect-secrets
    rev: v1.2.0
    hooks:
    - id: detect-secrets
      exclude: package.lock.json
tip

For more information on how to configure the .pre-commit-config, visit this page.


Set Git Template​

It is necessary to set in which directory the git template will be written:

git config --global init.templateDir <teplate-dir>
pre-commit init-templatedir <teplate-dir> -c <pre-commit-config-path>

Using the user's home as an example:

git config --global init.templateDir ~/.git-template
pre-commit init-templatedir ~/.git-template -c ~/.pre-commit-config.yaml

Clone a Repository​

Now whenever a repository is cloned or initialized, it will have the hooks set up already (<repo>/.git/hooks/pre-commit).

As an example, let's try to commit a file that contains a secret token:

❯ git commit -m "Testing secret leak"

Detect secrets.......................................Failed
- hook id: detect-secrets
- exit code: 1

ERROR: Potential secrets about to be committed to git repo!

Secret Type: Base64 High Entropy String
Location:    service.py:9

The commit correctly fails so that the secret is not leaked.