Blockchain Transaction Monitor

A scalable microservice written in Go that monitors Bitcoin, Ethereum, and Solana blockchains for transactions involving specified addresses. The service connects via RPC to blockchain nodes, processes transactions in real-time, and publishes events to Kafka.

Features

• Multi-blockchain Support: Monitor Bitcoin, Ethereum, and Solana simultaneously
• Real-time Processing: Handle high-throughput blockchains like Solana efficiently
• Scalable Architecture: Built with concurrent processing and proper error handling
• Event Publishing: Publishes transaction events to Kafka for downstream processing
• Configurable: Flexible configuration via environment variables
• Health Monitoring: Built-in health checks and statistics reporting
• Graceful Shutdown: Proper cleanup and graceful shutdown handling

Architecture

┌─────────────────┐    ┌─────────────────┐    ┌─────────────────┐
│   Bitcoin RPC   │    │  Ethereum RPC   │    │   Solana RPC    │
└─────────┬───────┘    └─────────┬───────┘    └─────────┬───────┘
          │                      │                      │
          └──────────────────────┼──────────────────────┘
                                 │
                    ┌─────────────▼──────────────┐
                    │   Blockchain Clients       │
                    │   - Bitcoin Client         │
                    │   - Ethereum Client        │
                    │   - Solana Client          │
                    └─────────────┬──────────────┘
                                 │
                    ┌─────────────▼──────────────┐
                    │   Transaction Monitor      │
                    │   - Block Processing       │
                    │   - Address Filtering      │
                    │   - Event Generation       │
                    └─────────────┬──────────────┘
                                 │
                    ┌─────────────▼──────────────┐
                    │   Kafka Producer           │
                    │   - Event Publishing       │
                    │   - Batching & Compression │
                    └────────────────────────────┘

Transaction Event Schema

Each transaction event published to Kafka contains:

{
  "event_id": "eth_0x1234..._%d",
  "timestamp": "2024-01-15T10:30:00Z",
  "blockchain": "ethereum",
  "user_id": "user123",
  "transaction_id": "0x1234567890abcdef...",
  "block_height": 18500000,
  "source": "0xabc123...",
  "destination": "0xdef456...",
  "amount": "1000000000000000000",
  "fees": "21000000000000000",
  "confirmations": 12,
  "status": "confirmed",
  "raw_data": { /* blockchain-specific data */ }
}

Quick Start

Prerequisites

• Go 1.21 or higher
• Docker and Docker Compose
• Access to blockchain RPC endpoints (Blockdaemon, Infura, etc.)

1. Clone and Setup

git clone <repository-url>
cd blockchain-monitor
go mod download

2. Start Kafka Infrastructure

# Start Kafka and Zookeeper
docker-compose up -d

# Verify Kafka is running
docker-compose ps

# View Kafka UI at http://localhost:8080

3. Configure Environment

Create a .env file:

# Blockchain RPC Configuration
BITCOIN_RPC_URL=https://bitcoin-mainnet.blockdaemon.com/rpc
BITCOIN_RPC_USERNAME=your_username
BITCOIN_RPC_PASSWORD=your_password

ETHEREUM_RPC_URL=https://ethereum-mainnet.blockdaemon.com/rpc
ETHEREUM_WS_URL=wss://ethereum-mainnet.blockdaemon.com/ws
ETHEREUM_API_KEY=your_api_key

SOLANA_RPC_URL=https://solana-mainnet.blockdaemon.com/rpc
SOLANA_WS_URL=wss://solana-mainnet.blockdaemon.com/ws

# Kafka Configuration
KAFKA_BROKERS=localhost:9092
KAFKA_TOPIC=blockchain-transactions

# Monitored Addresses (JSON format)
MONITORED_ADDRESSES={"user1":{"bitcoin":["1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa"],"ethereum":["0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"],"solana":["11111111111111111111111111111112"]}}

4. Run the Service

# Build and run
go build -o blockchain-monitor
./blockchain-monitor

# Or run directly
go run main.go

Configuration

Environment Variables

Variable	Description	Default
BITCOIN_RPC_URL	Bitcoin RPC endpoint	https://bitcoin-mainnet.blockdaemon.com/rpc
BITCOIN_RPC_USERNAME	Bitcoin RPC username	-
BITCOIN_RPC_PASSWORD	Bitcoin RPC password	-
ETHEREUM_RPC_URL	Ethereum RPC endpoint	https://ethereum-mainnet.blockdaemon.com/rpc
ETHEREUM_WS_URL	Ethereum WebSocket endpoint	wss://ethereum-mainnet.blockdaemon.com/ws
ETHEREUM_API_KEY	Ethereum API key	-
SOLANA_RPC_URL	Solana RPC endpoint	https://solana-mainnet.blockdaemon.com/rpc
SOLANA_WS_URL	Solana WebSocket endpoint	wss://solana-mainnet.blockdaemon.com/ws
KAFKA_BROKERS	Kafka broker addresses	localhost:9092
KAFKA_TOPIC	Kafka topic for events	blockchain-transactions
MONITORED_ADDRESSES	JSON string of addresses to monitor	See example
LOG_LEVEL	Logging level (debug, info, warn, error)	info
WORKER_POOL_SIZE	Number of worker goroutines	10
SHUTDOWN_TIMEOUT	Graceful shutdown timeout	30s

Monitored Addresses Format

The MONITORED_ADDRESSES environment variable should be a JSON string mapping user IDs to their addresses:

{
  "user1": {
    "bitcoin": ["1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa", "1BvBMSEYstWetqTFn5Au4m4GFg7xJaNVN2"],
    "ethereum": ["0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"],
    "solana": ["11111111111111111111111111111112"]
  },
  "user2": {
    "bitcoin": ["1234567890abcdef..."],
    "ethereum": ["0xabcdef123456..."],
    "solana": ["SolanaAddress123..."]
  }
}