Scalable Blockchain IoT

Lightweight blockchain platform for storing IoT sensor data with persistence support.

🏗️ Architecture

• Blockchain: Hardhat (dev/testing) + Ganache (persistent storage)
• API: Node.js + Express + Ethers.js
• Smart Contracts: Solidity

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🚀 Quick Start

Option 1: Hardhat (Development - No Persistence)

# Start services
docker-compose up -d

# Deploy contract
docker-compose exec blockchain yarn deploy

# Restart API
docker-compose restart api

# Test
curl http://localhost:3000/api/iot/info

Option 2: Ganache (Persistent Blockchain)

# Start services
docker-compose up -d

# Deploy contract to Ganache
docker-compose exec blockchain yarn deploy:ganache

# Restart Ganache API
docker-compose restart api-ganache

# Test
curl http://localhost:3001/api/iot/info

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🔌 Services & Ports

Service	Blockchain	API Port	RPC Port	Persistence
Hardhat	Development	3000	8545	❌ Resets on restart
Ganache	Production	3001	8546	✅ Disk-based

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📝 API Usage

Submit IoT Data

Hardhat:

curl -X POST http://localhost:3000/api/iot/data \
  -H "Content-Type: application/json" \
  -d '{"sensorId":"sensor-001","data":{"temp":25}}'

Ganache:

curl -X POST http://localhost:3001/api/iot/data \
  -H "Content-Type: application/json" \
  -d '{"sensorId":"sensor-001","data":{"temp":25}}'

Check Contract Info

# Hardhat
curl http://localhost:3000/api/iot/info

# Ganache
curl http://localhost:3001/api/iot/info

Submit Batch Data

curl -X POST http://localhost:3000/api/iot/batch \
  -H "Content-Type: application/json" \
  -d '{
    "readings": [
      {"sensorId":"sensor-001","data":{"temp":22.1}},
      {"sensorId":"sensor-002","data":{"temp":24.7}}
    ]
  }'

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🧪 Testing Ganache Persistence

# 1. Deploy and submit data
docker-compose exec blockchain yarn deploy:ganache
curl -X POST http://localhost:3001/api/iot/data \
  -H "Content-Type: application/json" \
  -d '{"sensorId":"test","data":{"temp":30}}'

# 2. Check totalSubmissions
curl http://localhost:3001/api/iot/info
# Should show: "totalSubmissions": "1"

# 3. Restart Ganache
docker-compose restart blockchain-ganache api-ganache

# 4. Verify data persisted
curl http://localhost:3001/api/iot/info
# Should STILL show: "totalSubmissions": "1" ✅

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🔄 Service Management

Restart Services

# Restart Hardhat
docker-compose restart blockchain api

# Restart Ganache
docker-compose restart blockchain-ganache api-ganache

# Restart everything
docker-compose restart

Rebuild After Code Changes

docker-compose down
docker-compose up -d --build

View Logs

# Hardhat
docker logs -f blockchain-hardhat
docker logs -f iot-api

# Ganache
docker logs -f blockchain-ganache
docker logs -f iot-api-ganache

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💾 Blockchain Snapshots (Hardhat Only)

Hardhat resets on restart. Use snapshots for reference:

# Export snapshot (saves current state)
docker-compose exec blockchain yarn snapshot:export

# Import snapshot (restore reference data)
docker-compose exec blockchain yarn snapshot:import

# List snapshots
docker-compose exec blockchain yarn snapshot:list

Note: Snapshots are reference-only. For true persistence, use Ganache.

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📊 API Endpoints

Endpoint	Method	Description
/health	GET	Health check
/api/iot/info	GET	Contract info & totalSubmissions
/api/iot/stats	GET	Blockchain statistics
/api/iot/data	POST	Submit single reading
/api/iot/batch	POST	Submit batch readings (max 50)

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🔧 Troubleshooting

API won't start

# Check if contract is deployed
docker exec blockchain-hardhat cat /data/deployed-contracts.json
docker exec blockchain-ganache ls /ganache_data

# Redeploy if missing
docker-compose exec blockchain yarn deploy        # Hardhat
docker-compose exec blockchain yarn deploy:ganache  # Ganache

Persistence not working (Ganache)

# Check Ganache data directory
docker exec blockchain-ganache ls -la /ganache_data

# Verify volume mount
docker inspect blockchain-ganache | grep ganache_data

Clear all data and start fresh

docker-compose down -v
rm -rf data/ganache/*
docker-compose up -d --build

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🎯 Use Cases

• Hardhat: Fast development, testing, contract debugging
• Ganache: Production-like environment with data persistence

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📄 License

MIT