How to handle GitHub leaks and .env files

March 16, 2025 (2w ago)

Guide to Removing Secrets from Git History and Handling .env Files

This guide covers two primary methods for permanently removing files from Git history: using BFG Repo-Cleaner and git-filter-repo. Both methods have their own benefits and considerations. It is important to follow safety precautions as these operations rewrite history, which can affect collaborators.

Table of Contents

  1. Introduction
  2. Safety Considerations
  3. Using BFG Repo-Cleaner
  4. Using git-filter-repo
  5. Best Practices for .env Files
  6. Conclusion

Introduction

Sometimes, sensitive files or large binaries accidentally get committed to a Git repository. Simply deleting them in a new commit won't remove them from the repository's history. This guide shows how to completely remove such files from the history.

Safety Considerations

  • Backup: Always create a backup of your repository before performing history rewrites.
  • Communication: Inform your team about the changes because everyone will need to re-clone the repository after history has been rewritten.
  • Testing: Clone your repository and test the changes in a separate environment before pushing to the main repository.

Using BFG Repo-Cleaner

BFG Repo-Cleaner is a simpler and faster alternative to git-filter-branch for removing unwanted data from Git repositories.

Installation

  1. Download the BFG jar file from the official website.
  2. Place the jar file in a directory included in your PATH or reference it directly.

Removing Files

  1. Clone the repository (mirror):

    git clone --mirror https://github.com/your-repo.git
cd your-repo.git

  2. Run BFG Repo-Cleaner:

    java -jar bfg.jar --delete-files your-file.ext

    To remove files matching a pattern:

    java -jar bfg.jar --delete-files '*.ext'

  3. Clean up and remove unwanted data:

    git reflog expire --expire=now --all && git gc --prune=now --aggressive

Pushing Changes

  1. Push the changes to the remote repository: 
    git push --force

Using git-filter-repo

git-filter-repo is a powerful tool from the Git project for rewriting Git history.

Installation

  1. Install git-filter-repo: 
    pip install git-filter-repo

Removing Files

  1. Clone the repository:

    git clone https://github.com/your-repo.git
cd your-repo

  2. Run git-filter-repo to remove files:

    git filter-repo --path your-file.ext --invert-paths

    To remove files matching a pattern:

    git filter-repo --path-glob '*.ext' --invert-paths

Pushing Changes

  1. Push the changes to the remote repository: 
    git push --force

Best Practices for .env Files

.env Files

.env files are used to store environment variables for applications. They are typically not committed to the repository to avoid exposing sensitive information.

Example of a .env file (you would put the actual values in your local copy):

# Database configuration
DB_HOST=localhost
DB_USER=username
DB_PASS=password
DB_NAME=database_name

# API keys
API_KEY=your_api_key_here

Ignoring .env Files

Environment variables often contain sensitive information like API keys, database credentials, and other configuration details. To prevent these from being pushed to the repository:

  1. Create a .gitignore file (if it doesn't exist):

    touch .gitignore

  2. Add .env to .gitignore:

    # .gitignore
.env

  3. Remove any tracked .env files: If the .env file has already been committed, you need to remove it from the repository:

    git rm --cached .env
git commit -m "Remove .env file from repository"
git push

Loading .env Files

To load .env files into your application, use a library that reads environment variables from a .env file and sets them in the environment. Here are examples for popular programming languages:

  1. Node.js (using dotenv):

    npm install dotenv

    In your entry file (e.g., app.js):

    require('dotenv').config();

// Access variables
console.log(process.env.MY_SECRET);

  2. Python (using python-dotenv):

    pip install python-dotenv

    In your script:

    from dotenv import load_dotenv
import os

load_dotenv()

# Access variables
secret = os.getenv("MY_SECRET")
print(secret)

  3. Ruby (using dotenv):

    gem install dotenv

    In your script:

    require 'dotenv/load'

# Access variables
secret = ENV['MY_SECRET']
puts secret

Conclusion

Removing files from Git history is a powerful operation that should be done with care. Whether you choose BFG Repo-Cleaner or git-filter-repo, make sure to follow the safety considerations to avoid disrupting your workflow. Always backup your repository and communicate with your team before pushing the rewritten history to the remote repository.

Additionally, handling .env files properly by ignoring them in Git and loading them securely in your application ensures that sensitive information is protected.