# Configuration

## Environment Variables

### Application

| Variable | Description | Example |
|----------|-------------|---------|
| `NODE_ENV` | Runtime environment | `production` |
| `PORT` | API server port | `3000` |
| `LOG_LEVEL` | Logging verbosity | `info` |

### Database

| Variable | Description | Example |
|----------|-------------|---------|
| `DB_HOST` | PostgreSQL host | `postgres.internal` |
| `DB_PORT` | PostgreSQL port | `5432` |
| `DB_USER` | Database user | `license_app` |
| `DB_PASSWORD` | Database password | `<secure>` |
| `DB_NAME` | Database name | `license_prod` |

### Authentication

| Variable | Description | Example |
|----------|-------------|---------|
| `JWT_SECRET` | Token signing key | `<64-char-random>` |
| `JWT_EXPIRY` | Token lifetime | `3600` |

### Blockchain

| Variable | Description | Example |
|----------|-------------|---------|
| `BESU_RPC_URL` | Besu JSON-RPC endpoint | `http://besu:8545` |
| `CONTRACT_ADDRESS` | NFT contract address | `0x123...` |
| `WALLET_PRIVATE_KEY` | Signing wallet key | `<secure>` |

### External Services

| Variable | Description | Example |
|----------|-------------|---------|
| `DIGILOCKER_CLIENT_ID` | DigiLocker OAuth client | `<client-id>` |
| `DIGILOCKER_SECRET` | DigiLocker OAuth secret | `<secret>` |
| `SMTP_HOST` | Email server | `smtp.gov.in` |
| `SMS_API_KEY` | SMS gateway key | `<api-key>` |

## Configuration Files

### `config/production.yaml`

```yaml
server:
  port: 3000
  cors:
    origins:
      - https://license.gov.in
      - https://admin.license.gov.in

database:
  pool:
    min: 5
    max: 20

blockchain:
  confirmations: 2
  gasLimit: 500000

upload:
  maxSize: 10485760  # 10MB
  allowedTypes:
    - application/pdf
    - image/jpeg
    - image/png
```

## Secrets Management

Store sensitive values in:
- Environment variables (Docker/Kubernetes)
- HashiCorp Vault
- AWS Secrets Manager

Never commit secrets to version control.