DAI Indexer

A real-time DAI token transaction indexer built with NestJS that monitors and tracks DAI transfers on the Ethereum mainnet.

What is this?

DAI Indexer is a blockchain monitoring application that:

• Real-time Monitoring: Listens to DAI token transfer events on Ethereum mainnet using WebSocket connections
• Transaction Tracking: Accumulates statistics about DAI transfers including total volume and transaction count
• Transaction Validation: Provides an API to check if any given transaction hash involves DAI token operations
• Live Statistics: Offers real-time insights into DAI token activity since the application started

The DAI token (0x6B175474E89094C44Da98b954EedeAC495271d0F) is a popular stablecoin on Ethereum, and this indexer helps track its movement across the network.

Features

• Real-time DAI transfer event monitoring
• Cumulative transaction statistics
• Transaction hash validation for DAI operations
• RESTful API endpoints
• Built with TypeScript and NestJS
• Uses Infura for reliable Ethereum node access
• Comprehensive error handling

Technology Stack

• Framework: NestJS - A progressive Node.js framework
• Blockchain: Ethers.js - Ethereum library for blockchain interactions
• Provider: Infura - Ethereum node infrastructure
• Language: TypeScript
• Runtime: Node.js

Prerequisites

Before you begin, ensure you have:

• Node.js (v14 or higher)
• Yarn package manager
• An Infura account and API key for Ethereum mainnet access

Installation

1. Clone the repository

   git clone <repository-url>
   cd dai-indexer

2. Install dependencies

   yarn install

3. Set up environment variables

   cp .env.example .env

   Edit the .env file and set your Infura API key:

   INFURA_KEY=your_infura_api_key_here

4. Start the application

   yarn start

   For development with auto-reload:

   yarn start:dev

The application will start on http://localhost:3000

API Endpoints

Get DAI Statistics

GET /transactions

Returns comprehensive statistics about DAI transfers since the application started.

Response:

{
  "startTime": 1642684800000,
  "currentTime": 1642688400000,
  "totalTransactions": 1547,
  "totalDAITransactions": "1234567.89 DAI"
}

Example:

curl http://localhost:3000/transactions

Validate DAI Transaction

GET /transactions/:transactionHash

Checks if a given transaction hash involves DAI token operations.

Parameters:

• transactionHash - Ethereum transaction hash (with or without 0x prefix)

Response:

true  // if transaction involves DAI
false // if transaction doesn't involve DAI or doesn't exist

Example:

curl http://localhost:3000/transactions/0x1234567890abcdef...

Architecture

The application follows a modular architecture:

src/
├── transactions/           # Transaction monitoring module
│   ├── transactions.controller.ts   # API endpoints
│   ├── transactions.service.ts      # Core business logic
│   └── transactions.spec.ts         # Unit tests
├── abi.json               # DAI token ABI for contract interaction
├── types.ts               # TypeScript type definitions
├── app.module.ts          # Main application module
└── main.ts                # Application bootstrap

Key Components

• TransactionsService: Handles WebSocket connection to Ethereum, monitors Transfer events, and maintains statistics
• TransactionsController: Exposes REST API endpoints for accessing data
• Real-time Event Handler: Processes DAI transfer events as they occur on the blockchain

How It Works

1. Connection: The app establishes a WebSocket connection to Ethereum mainnet via Infura
2. Event Listening: Subscribes to Transfer events from the DAI token contract
3. Data Accumulation: Each transfer event updates the running total and transaction count
4. API Access: Provides real-time access to accumulated data and transaction validation

Testing

Run the test suite:

# Unit tests
yarn test

# End-to-end tests
yarn test:e2e

# Test coverage
yarn test:cov

Available Scripts

• yarn start - Start the application
• yarn start:dev - Start in development mode with auto-reload
• yarn start:prod - Start in production mode
• yarn build - Build the application
• yarn test - Run unit tests
• yarn test:e2e - Run end-to-end tests
• yarn lint - Lint the codebase
• yarn format - Format code with Prettier

Contributing

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

License

This project is licensed under the UNLICENSED license.

Author

@javierlinked
2022

---

Built with ❤️ for the Ethereum and DeFi community