PreCommit.md

TruffleHog Pre-Commit Hooks

Pre-commit hooks are scripts that run automatically before a commit is completed, allowing you to check your code for issues before sharing it with others. TruffleHog can be integrated as a pre-commit hook to prevent credentials from leaking before they ever leave your computer.

This guide covers how to set up TruffleHog as a pre-commit hook using two popular frameworks:

1. Git's hooksPath feature - A built-in Git feature for managing hooks globally
2. Using Pre-commit framework - A language-agnostic framework for managing pre-commit hooks
3. Using Husky - A Git hooks manager for JavaScript/Node.js projects

Prerequisites

All of the methods require TruffleHog to be installed.

1. Install TruffleHog:

# Using Homebrew (macOS)
brew install trufflehog

# Using installation script for Linux, macOS, and Windows (and WSL)
curl -sSfL https://raw.githubusercontent.com/trufflesecurity/trufflehog/main/scripts/install.sh | sh -s -- -b /usr/local/bin

Global setup using Git's hooksPath feature

This approach uses Git's core.hooksPath to apply hooks to all repositories without requiring any per-repository setup:

1. Create a global hooks directory:

mkdir -p ~/.git-hooks

2. Create a pre-commit hook file:

touch ~/.git-hooks/pre-commit
chmod +x ~/.git-hooks/pre-commit

3. Configure Git Hook Script

Standard Installation

Option A: Auto-configured (Recommended)

TruffleHog automatically detects the TRUFFLEHOG_PRE_COMMIT environment variable and applies optimal pre-commit settings.

#!/bin/sh
export TRUFFLEHOG_PRE_COMMIT=1
trufflehog git file://.

Option B: Manual-configuration

Manual configuration (only if you need custom behavior). Do NOT set TRUFFLEHOG_PRE_COMMIT if using manual configuration.

#!bin/sh
trufflehog git file://. --since-commit HEAD --results=verified,unknown --fail --trust-local-git-config

Docker Installation

Option A: Auto-configured (Recommended)

#!/bin/sh
# Set environment variable inside container (recommended)
docker run --rm \
  -v "$(pwd):/workdir" \
  -e "TRUFFLEHOG_PRE_COMMIT=1" \
  trufflesecurity/trufflehog:latest \
  git file:///workdir

Option B: Manual-configuration

#!/bin/sh

docker run --rm -v "$(pwd):/workdir" -i --rm trufflesecurity/trufflehog:latest git file:///workdir --since-commit HEAD --results=verified,unknown --fail

4. Configure Git to use this hooks directory globally:

git config --global core.hooksPath ~/.git-hooks

Now all your repositories will automatically use this pre-commit hook without any additional setup.

Using the Pre-commit Framework

The pre-commit framework is a powerful, language-agnostic tool for managing Git hooks.

Installation of Pre-commit

1. Install the pre-commit framework:

# Using pip (Python)
pip install pre-commit

# Using Homebrew (macOS)
brew install pre-commit

# Using conda
conda install -c conda-forge pre-commit

Repository-Specific Setup

To set up TruffleHog as a pre-commit hook for a specific repository:

1. Create a .pre-commit-config.yaml file in the root of your repository:

TruffleHog automatically detects when running under the pre-commit.com framework and applies optimal settings. No additional configuration is needed.

repos:
  - repo: local
    hooks:
      - id: trufflehog
        name: TruffleHog
        description: Detect secrets in your data.
        entry: bash -c 'trufflehog git file://.'
        language: system
        stages: ["pre-commit", "pre-push"]

If TruffleHog doesn't auto-detect your pre-commit.com environment, you can manually specify the recommended pre-commit settings:

repos:
  - repo: local
    hooks:
      - id: trufflehog
        name: TruffleHog
        description: Detect secrets in your data.
        entry: bash -c 'trufflehog git file://. --since-commit HEAD --results=verified,unknown --fail --trust-local-git-config'
        language: system
        stages: ["pre-commit", "pre-push"]

2. Install the pre-commit hook:

pre-commit install

Using Husky

Husky is a popular tool for managing Git hooks in JavaScript/Node.js projects.

Installation of Husky

1. Install Husky in your project:

# npm
npm install husky --save-dev

# yarn
yarn add husky --dev

2. Enable Git hooks:

# npm
npx husky init

Setting Up TruffleHog with Husky

1. Add the following content to .husky/pre-commit:

TruffleHog automatically detects when running under the Husky framework and applies optimal settings. No additional configuration is needed.

echo "trufflehog git file://." > .husky/pre-commit

If TruffleHog doesn't auto-detect your husky framework, you can manually specify the recommended pre-commit settings:

echo "trufflehog git file://. --since-commit HEAD --results=verified,unknown --fail --trust-local-git-config" > .husky/pre-commit

2. For Docker users, use this content instead:

echo 'docker run --rm -v "$(pwd):/workdir" -i --rm trufflesecurity/trufflehog:latest git file:///workdir' > .husky/pre-commit

Best Practices

Commit Process

For optimal hook efficacy:

1. Execute git add followed by git commit separately. This ensures TruffleHog analyzes all intended changes.
2. Avoid using git commit -am, as it might bypass pre-commit hook execution for unstaged modifications.

Skipping Hooks

In rare cases, you may need to bypass pre-commit hooks:

git commit --no-verify -m "Your commit message"

Running in Audit Mode (Without TRUFFLEHOG_PRE_COMMIT env variable)

You can run the TruffleHog pre-commit hook in an "audit" or "non-enforcement" mode to test the git hook with the following commands:

Local Binary Version:

trufflehog git file://. --since-commit HEAD --results=verified,unknown 2>/dev/null

Docker Container Version:

docker run --rm -v "$(pwd):/workdir" -i --rm trufflesecurity/trufflehog:latest git file:///workdir --since-commit HEAD --results=verified,unknown 2>/dev/null

This change does two things: (1) removes the --fail flag, which means the pre-commit hook will always pass, (2) suppresses stderr output, so only verified secrets are printed to the terminal output.

For users of the Pre-Commit Framework: add the verbose: true flag during audit mode; otherwise, the hook will pass, and you won't see any secrets.

Troubleshooting

Hook Not Running

If your pre-commit hook isn't running:

1. Ensure the hook is executable:

   chmod +x .git/hooks/pre-commit

2. Check if hooks are enabled:

   git config --get core.hooksPath

False Positives

If you're getting false positives:

1. Use the --results=verified flag to only show verified secrets
2. Add trufflehog:ignore comments on lines with known false positives or risk-accepted findings

Conclusion

By integrating TruffleHog into your pre-commit workflow, you can prevent credential leaks before they happen. Choose the setup method that best fits your project's needs and development workflow.

For more information on TruffleHog's capabilities, refer to the main documentation.