Configuration
Environment Variables
When running with Docker Compose, configuration is done through the .env file. Copy .env.example and edit:
| Variable | Required | Default | Description |
|---|---|---|---|
PARENT_CHAIN_RPC_URL | Yes | - | Ethereum L1 RPC endpoint (Sepolia for testnet) |
PARENT_CHAIN_BEACON_URL | Yes | - | Ethereum Beacon API endpoint |
CHAIN_ID | No | 421614 | Arbitrum chain ID (421614 = Sepolia) |
NITRO_IMAGE | No | offchainlabs/nitro-node:v3.10.0-rc.2-746bda2 | Consensus node Docker image |
FEED_URL | No | wss://sepolia-rollup.arbitrum.io/feed | Sequencer feed for faster sync |
LOG_LEVEL | No | WARN | Consensus node log level (TRACE/DEBUG/INFO/WARN/ERROR) |
RUST_LOG | No | warn | Execution client log level |
DATA_DIR | No | Docker volume | Host path for execution data |
NITRO_DATA_DIR | No | Docker volume | Host path for consensus data |
CLI Options
ArbReth inherits all of reth's CLI options. The most commonly used:
Node
arb-reth node [OPTIONS]| Flag | Description |
|---|---|
--chain <PATH> | Path to chain genesis JSON |
--datadir <PATH> | Database directory |
--http | Enable HTTP JSON-RPC server |
--http.addr <ADDR> | HTTP listen address (default: 127.0.0.1) |
--http.port <PORT> | HTTP port (default: 8545) |
--http.api <APIS> | Comma-separated API namespaces (eth,web3,net,debug) |
--authrpc.addr <ADDR> | Engine API listen address |
--authrpc.port <PORT> | Engine API port (default: 8551) |
--authrpc.jwtsecret <PATH> | Path to JWT secret file |
--disable-discovery | Disable P2P discovery (recommended for Arbitrum) |
--rollup.sequencer | Enable sequencer mode |
Database
| Flag | Description |
|---|---|
--db.exclusive=true | Exclusive database access (recommended) |
--db.growth-step <SIZE> | MDBX growth step (e.g., 4GB) |
--db.log-level <LEVEL> | Database log level |
--db.sync-mode <MODE> | Sync mode (safe-no-sync for performance) |
Logging
| Flag | Description |
|---|---|
--log.stdout.filter <FILTER> | Log filter for stdout (e.g., warn, info, debug) |
Genesis Files
ArbReth ships with genesis configurations in the genesis/ directory:
genesis/arbitrum-sepolia.json- Arbitrum Sepolia testnet
The genesis file contains the initial chain configuration, alloc entries for precompile contracts, and the ArbOS state initialization at the ArbOS state address (0xa4b05...).
Key Genesis Parameters
| Field | Value | Meaning |
|---|---|---|
chainId | 421614 | Arbitrum Sepolia |
difficulty | 1 | Constant (proof-of-authority) |
baseFeePerGas | 100 Gwei | Initial L2 base fee |
gasLimit | Very large | Arbitrum manages gas limits through ArbOS |
mixHash | Encodes ArbOS v10 | Initial ArbOS version embedded in header |