@blobkit/proxy-server

Express.js server that executes EIP-4844 blob transactions on behalf of browser clients after verifying escrow payments.

Installation

npm install @blobkit/proxy-server

Requirements

• Node.js v18 or later
• Redis 6.0 or later (for persistent job queue)

Usage

# Using CLI
npx blobkit-proxy --rpc-url $RPC_URL \
                  --private-key $PRIVATE_KEY \
                  --escrow-contract 0x1234567890123456789012345678901234567890

# Using environment variables
export RPC_URL=$MAINNET_RPC_URL
export PRIVATE_KEY=$PRIVATE_KEY
export ESCROW_CONTRACT=0x1234567890123456789012345678901234567890
npx blobkit-proxy

Configuration

| Environment Variable | Required | Default | Description | | ------------------------ | -------- | ---------------------- | -------------------------------- | | RPC_URL | Yes | - | Ethereum RPC endpoint | | ESCROW_CONTRACT | Yes | - | Escrow contract address | | KZG_TRUSTED_SETUP_PATH | Yes | - | Path to KZG trusted setup file | | REQUEST_SIGNING_SECRET | Yes | - | HMAC secret (min 32 chars) | | PRIVATE_KEY | No* | - | Private key for dev (see below) | | AWS_KMS_KEY_ID | No* | - | AWS KMS key ARN for production | | PORT | No | 3000 | Server port | | HOST | No | 0.0.0.0 | Server host | | CHAIN_ID | No | 1 | Ethereum chain ID | | PROXY_FEE_PERCENT | No | 0 | Fee percentage (0-10) | | LOG_LEVEL | No | info | Log level: debug/info/warn/error | | REDIS_URL | No | redis://localhost:6379 | Redis connection URL |

*One key management option required (PRIVATE_KEY for development, AWS_KMS_KEY_ID for production)

KZG Trusted Setup

The proxy server requires a KZG trusted setup for creating blob commitments and proofs:

• Default: Uses the built-in Ethereum mainnet trusted setup
• Custom: Specify a path with KZG_TRUSTED_SETUP_PATH environment variable

# Use custom trusted setup
export KZG_TRUSTED_SETUP_PATH=/path/to/trusted_setup.txt
npx blobkit-proxy

The trusted setup file should be in the standard Ethereum KZG ceremony format. Download from ceremony.ethereum.org.

Redis Persistence

The proxy server uses Redis for persistent job queue management. This ensures that pending job completions survive server restarts.

Redis Setup

# Using Docker
docker run -d -p 6379:6379 redis:7-alpine

# Using Homebrew (macOS)
brew install redis
brew services start redis

# Using apt (Ubuntu/Debian)
sudo apt update
sudo apt install redis-server
sudo systemctl start redis-server

Redis Configuration

The server connects to Redis using the REDIS_URL environment variable. Examples:

# Local Redis
REDIS_URL=redis://localhost:6379

# Redis with authentication
REDIS_URL=redis://username:password@hostname:6379

# Redis with TLS
REDIS_URL=rediss://hostname:6380

Testing and Development

npm test               # Run tests
npm run test:coverage  # Run tests with coverage
npm run build          # Build for production
npm run dev            # Start development server
npm run lint           # Lint code
npm run type-check     # TypeScript checking

Documentation

See /docs/proxy/ for deployment guides and API documentation.