How to Extract Emails from GitHub Repositories

GitHub, being a central hub for open-source projects, often contains valuable information, including email addresses. Developers typically include email addresses in their GitHub profiles, commit messages, or even in documentation files. Extracting emails from GitHub repositories can be useful for networking, research, or outreach to project contributors.

In this blog, we will explore how to extract emails from GitHub repositories, focusing on programmatic approaches while ensuring compliance with ethical and legal guidelines.

Why Extract Emails from GitHub?

1. Networking: Reach out to developers for collaboration or open-source contributions.
2. Recruitment: Identify potential candidates based on their contributions to open-source projects.
3. Outreach: Contact repository maintainers for support, partnerships, or information sharing.

Prerequisites

To start extracting emails from GitHub repositories, you will need:

• A GitHub account.
• GitHub API access to query repository data.
• Basic programming knowledge (we will use Python for this tutorial).

Step 1: Using the GitHub API

GitHub offers an API that allows you to access repositories, commits, and user information. You can use this API to extract email addresses from commit messages or user profiles.

First, you need to generate a personal access token on GitHub. Here’s how:

1. Go to GitHub’s settings.
2. Navigate to “Developer Settings” → “Personal Access Tokens.”
3. Generate a new token with repository access.

Now, let’s use Python and the requests library to interact with the GitHub API.

Install the Required Dependencies

If you haven’t already installed the requests library, do so by running:

pip install requests

Step 2: Extracting Emails from Commit Messages

Emails are often embedded in commit messages. Each time a developer makes a commit, the email associated with their GitHub account may be included. Here’s how to extract emails from the commit history of a repository.

import requests

# GitHub API URL for repository commits
def get_commits(repo_owner, repo_name, token):
    url = f"https://api.github.com/repos/{repo_owner}/{repo_name}/commits"
    headers = {
        "Authorization": f"token {token}"
    }
    response = requests.get(url, headers=headers)
    
    if response.status_code == 200:
        return response.json()
    else:
        print(f"Error: {response.status_code}")
        return None

def extract_emails_from_commits(commits):
    emails = set()
    for commit in commits:
        commit_author = commit.get('commit').get('author')
        if commit_author:
            email = commit_author.get('email')
            if email and "noreply" not in email:  # Ignore GitHub-generated emails
                emails.add(email)
    return emails

# Example usage
repo_owner = 'octocat'
repo_name = 'Hello-World'
token = 'your_github_token'

commits = get_commits(repo_owner, repo_name, token)

if commits:
    emails = extract_emails_from_commits(commits)
    print("Found emails:", emails)
else:
    print("No commit data found.")

In this example:

• We query the GitHub API for the commit history of a repository.
• We extract emails from the commit.author field, filtering out generic GitHub noreply emails.

Step 3: Extracting Emails from User Profiles

GitHub profiles sometimes include an email address, especially when developers make them public. You can fetch user profiles using the GitHub API.

Here’s how you can extract emails from user profiles:

def get_user_info(username, token):
    url = f"https://api.github.com/users/{username}"
    headers = {
        "Authorization": f"token {token}"
    }
    response = requests.get(url, headers=headers)
    
    if response.status_code == 200:
        return response.json()
    else:
        print(f"Error: {response.status_code}")
        return None

def extract_email_from_profile(user_info):
    email = user_info.get('email')
    if email:
        return email
    else:
        return "Email not publicly available"

# Example usage
username = 'octocat'
user_info = get_user_info(username, token)

if user_info:
    email = extract_email_from_profile(user_info)
    print(f"Email for {username}: {email}")
else:
    print("No user info found.")

This code fetches the GitHub profile of a user and extracts their email address if they have made it public.

Step 4: Extracting Emails from Repository Files

In some cases, emails might be hardcoded into files like README.md or CONTRIBUTING.md. To find emails inside repository files, you can clone the repository locally and use a regular expression to search for email patterns.

Here’s a Python example using regular expressions to find emails in a cloned repository:

import re
import os

def extract_emails_from_file(file_path):
    email_pattern = r'[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}'
    with open(file_path, 'r', encoding='utf-8', errors='ignore') as file:
        content = file.read()
        emails = re.findall(email_pattern, content)
        return set(emails)

def extract_emails_from_repo(repo_path):
    emails = set()
    for root, dirs, files in os.walk(repo_path):
        for file in files:
            file_path = os.path.join(root, file)
            file_emails = extract_emails_from_file(file_path)
            emails.update(file_emails)
    return emails

# Example usage
repo_path = '/path/to/cloned/repository'
emails = extract_emails_from_repo(repo_path)
print("Emails found in repository files:", emails)

In this approach:

• We use a regular expression to search for email patterns within the content of each file in the repository.
• This method can be helpful for extracting emails from documentation or code comments.

Ethical Considerations

When extracting emails from GitHub, it’s essential to follow ethical guidelines and legal obligations:

1. Privacy: Do not use extracted emails for spamming or unsolicited emails. Always ensure your communication is legitimate and respectful.
2. Rate Limiting: The GitHub API enforces rate limits. Ensure you handle API responses and errors appropriately, especially if making multiple API calls.
3. Open-Source Etiquette: When reaching out to developers, acknowledge their open-source contributions respectfully. Always ask for permission if you plan to use their information for any other purposes.

Conclusion

Extracting emails from GitHub repositories can be valuable for outreach, research, or networking. By using the GitHub API or regular expressions, you can efficiently extract email addresses from commit histories, user profiles, and repository files.

However, with great power comes great responsibility. Always use the information ethically, respecting the privacy and work of developers on GitHub. By following these best practices, you can effectively leverage GitHub’s rich data for productive and respectful communication.