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System design for github - System design interview

Designing a system similar to GitHub involves several key components and considerations. Below is a high-level overview of the components and the tech stack involved, along with simplified code snippets to illustrate basic concepts.

Components of a GitHub-like System

  1. Backend Server

    • Manages user authentication, repository storage, version control (commits, branches), collaboration features (issues, pull requests).
    • Tech Stack: Node.js, Express.js, MongoDB or PostgreSQL (for data storage), Git (for version control operations).
  2. Database

    • Stores user profiles, repositories, commits, issues, pull requests, etc.
    • Tech Stack: MongoDB or PostgreSQL for relational data storage.
  3. Authentication

    • Registers users, manages login/logout, and access control.
    • Tech Stack: JSON Web Tokens (JWT) for authentication, bcrypt for password hashing.
  4. Version Control System (VCS)

    • Handles repository operations: creating repositories, making commits, branching, merging, etc.
    • Tech Stack: Git (using Git commands via Git CLI or libraries like libgit2).
  5. Collaboration Features

    • Enables collaboration through issues, pull requests, code reviews, and notifications.
    • Tech Stack: WebSockets (for real-time updates), RESTful APIs for CRUD operations.
  6. Frontend Client (Web Interface)

    • Provides user interface for repository browsing, code viewing, commit history, pull request management, etc.
    • Tech Stack: React.js, Redux for state management, Bootstrap or Material UI for UI components.
  7. Notifications

    • Sends notifications for activities like pull requests, issue updates, and mentions.
    • Tech Stack: WebSocket (for real-time notifications), Email notifications.

Low-Level Overview and Sample Code

Here's a simplified outline with sample code snippets for key components:

Backend Server (Node.js with Express)

  1. User Authentication and Registration

    const express = require('express');
    const bcrypt = require('bcrypt');
    const jwt = require('jsonwebtoken');
    const User = require('./models/User');
    
    const app = express();
    const secretKey = 'your_secret_key';
    
    // Register a new user
    app.post('/api/register', async (req, res) => {
        try {
            const { username, password } = req.body;
            const hashedPassword = await bcrypt.hash(password, 10);
            const newUser = new User({ username, password: hashedPassword });
            await newUser.save();
            res.status(201).json({ message: 'User registered successfully' });
        } catch (err) {
            res.status(500).json({ error: err.message });
        }
    });
    
    // User login
    app.post('/api/login', async (req, res) => {
        try {
            const { username, password } = req.body;
            const user = await User.findOne({ username });
            if (!user) {
                return res.status(404).json({ message: 'User not found' });
            }
            const isMatch = await bcrypt.compare(password, user.password);
            if (!isMatch) {
                return res.status(401).json({ message: 'Invalid credentials' });
            }
            const token = jwt.sign({ userId: user._id }, secretKey, { expiresIn: '1h' });
            res.json({ token });
        } catch (err) {
            res.status(500).json({ error: err.message });
        }
    });
    
    app.listen(3000, () => {
        console.log('Server started on port 3000');
    });
    
  2. Repository and Version Control Operations

    const { exec } = require('child_process');
    const express = require('express');
    const app = express();
    
    // Initialize a new repository
    app.post('/api/repo/init', (req, res) => {
        const repoName = req.body.repoName;
        exec(`git init ${repoName}`, (error, stdout, stderr) => {
            if (error) {
                console.error(`exec error: ${error}`);
                return res.status(500).json({ error: 'Failed to initialize repository' });
            }
            console.log(`stdout: ${stdout}`);
            console.error(`stderr: ${stderr}`);
            res.status(200).json({ message: 'Repository initialized successfully' });
        });
    });
    
    // Make a commit
    app.post('/api/repo/commit', (req, res) => {
        const repoName = req.body.repoName;
        const commitMessage = req.body.message;
        exec(`git -C ${repoName} add . && git -C ${repoName} commit -m "${commitMessage}"`, (error, stdout, stderr) => {
            if (error) {
                console.error(`exec error: ${error}`);
                return res.status(500).json({ error: 'Failed to commit changes' });
            }
            console.log(`stdout: ${stdout}`);
            console.error(`stderr: ${stderr}`);
            res.status(200).json({ message: 'Changes committed successfully' });
        });
    });
    
    app.listen(3000, () => {
        console.log('Server started on port 3000');
    });
    

Frontend Client (React.js)

  1. Repository List and Navigation

    import React, { useState, useEffect } from 'react';
    import axios from 'axios';
    
    const RepositoryList = () => {
        const [repositories, setRepositories] = useState([]);
    
        useEffect(() => {
            axios.get('/api/repositories')
                .then(res => setRepositories(res.data))
                .catch(err => console.error('Error fetching repositories:', err));
        }, []);
    
        return (
            <div>
                <h1>My Repositories</h1>
                <ul>
                    {repositories.map(repo => (
                        <li key={repo.id}>
                            <a href={`/repo/${repo.id}`}>{repo.name}</a>
                        </li>
                    ))}
                </ul>
            </div>
        );
    };
    
    export default RepositoryList;
    

Considerations

Published on: Jul 10, 2024, 01:52 AM  
 

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