Relay Server

A high-performance, scalable backend for the Relay real-time chat application, built with modern technologies to ensure reliability, speed, and type safety.

Frontend Repository: https://github.com/SuperSahitya/relay

Tech Stack

• Runtime: Node.js
• Language: TypeScript
• Framework: Express.js
• Database: PostgreSQL (via Drizzle ORM)
• Real-time: Socket.io (with Redis Pub/Sub)
• Message Queue: Apache Kafka
• Caching & Store: Redis
• Authentication: Better Auth
• Validation: Zod
• Logging: Pino

Key Features

• Real-time Messaging: Instant, low-latency chat powered by websockets (Socket.io).
• Event-Driven Architecture: Utilizes Apache Kafka to decouple message ingestion from persistence, ensuring high throughput and reliability.
• Scalable WebSocket Infrastructure: Utilizes the Redis Pub/Sub model with websockets (Socket.io) to support horizontal scaling across multiple server instances.
• Robust Presence System: Real-time user online/offline tracking using Redis keys with TTL-based heartbeats, with Pub/Sub used for presence update fanout.
• Secure Authentication: Powered by Better Auth, implementing:
  • JWT & HTTP-Only Cookies: Secure session management using JSON Web Tokens stored in HTTP-only cookies to prevent XSS attacks.
  • Google OAuth: Seamless social login integration.
  • Email & Password: Secure credential-based login with mandatory email verification, and the credentials securely hashed and salted before storage.
  • SMTP Integration: Uses Nodemailer to send verification emails via an SMTP server.
• Secure & Rate Limited: Protected by robust authentication middleware and Redis-backed rate limiting to prevent abuse.
• Type-Safe Development: Comprehensive TypeScript integration with Zod for runtime request validation.

API Documentation

Authentication

• POST /api/auth/* - Handled by Better Auth (Sign up, Sign in, etc.)

User

• GET /api/users/me - Get current user profile
• GET /api/users/:id - Get specific user profile
• GET /api/search - Search for users

Friends

• GET /api/friends - Get list of friends
• POST /api/friends - Send a friend request
• PUT /api/friends/respond - Accept or decline a friend request
• DELETE /api/friends/:friendId - Remove a friend
• GET /api/friends/requests - Get received friend requests
• GET /api/friends/sent - Get sent friend requests

Messages

• GET /api/messages/:friendId - Get chat history with a friend

Real-time Events (Socket.io)

Emitters (Client -> Server)

• chat_message: Send a message to a user.
  • Payload: { receiverId: string, message: string }

Listeners (Server -> Client)

• chat_message: Receive a new message.
• presence_update: Receive updates on friends' online status.

Setup & Installation

1. Clone the repository

   git clone https://github.com/SuperSahitya/relay-server.git
   cd relay-server

2. Install dependencies

   pnpm install

3. Start Infrastructure (Docker)

   This project uses Docker Compose to run PostgreSQL, Redis, and Apache Kafka.

   docker-compose up -d

4. Environment Variables

   Create a .env file and configure the environment variables as per .env.example.

5. Run Database Migrations

   pnpm db:push

6. Start the Server

   pnpm dev