Skip to main content

Beta v4 migration guide

Linea Beta v4 is a mandatory hard fork introducing Maru, the new consensus layer (CL).

This replaces Clique and aligns Linea with Ethereum's dual-layer design (execution and consensus).

After the fork:

  • You must run both an execution layer (EL) client and Maru, a CL client
  • Sequencer signatures move from EL extraData to the Maru attestations API.
  • EL clients must be upgraded to Beta v4 compatible versions (any EL client that supports Prague should be compatible).

Breaking change: sequencer signatures

Sequencer signatures will no longer be in EL block extraData after the upgrade.

Before (pre-fork):

// on EL client
let signatures = block.extra_data;

After (post-fork):

// Must switch to Maru API
let signatures = maru_api.get("/eth/v2/beacon/blocks/{block_id}").data.message.body.attestations;

Attestations returns a list of the current block signature/attestation and the previous block signature/attestation.

Key architecture changes

Current

  • Single layer: EL client only (Besu with Clique consensus)
  • Sequencer signatures: Stored in EL block extraData
  • Block production: Clique handles execution and consensus

After Beta v4

  • Dual-layer architecture: Execution Layer (EL) client + Consensus Layer (CL) client (The CL is currently powered by Maru, a consensus client implementing a customized variation of the QBFT algorithm. While Maru is the only supported client today, the architecture is designed to support future client diversity and algorithm evolution).
  • Sequencer signatures: Moved to Maru's SealedBeaconBlock.commitSeals
  • Block production: Maru (QBFT) coordinates consensus, EL executes transactions
  • API: Signatures and consensus data available via Maru APIs

EL client compatibility

By design, Linea/Maru will support any client compatible with L1. So any vanilla client compatible with Prague will work.

Supported EL clients (from e2e tests):

  • Besu: 25.8.0 or higher
  • Geth: Use the latest release (downtime required)
  • Erigon: Use the latest release
  • Nethermind: Use the latest release
  • Linea-specific: A new linea-besu-package release will be provided separately

⚠️ Geth-specific issue:

  • Geth v1.15+ → incompatible with Clique (pre-fork)
  • Geth v1.13 → incompatible with Prague (post-fork)
  • Result: No zero-downtime upgrade path; must plan maintenance window.

Upgrade strategy

Depending on your EL client, follow the relevant upgrade path:

Besu, Erigon, Nethermind (zero-downtime)

Pre-upgrade

  • Prepare Docker setup (EL + Maru)
  • Upgrade EL client to Prague-compatible version

During upgrade

  • Start Maru before the fork timestamp
  • Keep EL client running
  • Monitor logs for sync and consensus:
    • docker logs linea-maru | grep "imported block"
    • curl -s -X POST http://localhost:8545 -H "Content-Type: application/json" -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'

Post-upgrade

  • Verify block import in Maru logs
  • Confirm EL block height with eth_blockNumber

⚠️ Geth (downtime required):

Pre-upgrade*

  • Prepare Docker setup (EL + Maru)
  • Plan a short maintenance window after the fork

During upgrade

  • Stop Geth after fork timestamp
  • Upgrade to Geth v1.15+ (Prague-compatible)
  • Start both Maru and Geth together

Post-upgrade

  • Same verification steps as above

Installation and setup guide

Prerequisites

Step 1: Directory structure

mkdir -p ~/linea-node/{maru/config,besu/config}
cd ~/linea-node

Step 2: Besu configuration (Sepolia)

Create besu/config/config.toml:

# Sepolia configuration
data-path="/opt/besu/data"
genesis-file="/opt/besu/genesis.json"

# Sepolia bootnodes
bootnodes=[
"enode://6f20afbe4397e51b717a7c1ad3095e79aee48c835eebd9237a3e8a16951ade1fe0e66e981e30ea269849fcb6ba03d838da37f524fabd2a557474194a2e2604fa@18.221.100.27:31002",
"enode://ce1e0d8e0500cb5c0ac56bdcdafb2d6320c3a2c5125b5ccf12f5dfc9b47ee74acbcafc32559017613136c9c36a0ce74ba4f83b7fb8244f099f3b15708d9d3129@3.23.75.47:31000",
"enode://1b026a5eb0ae74300f58987d235ef0e3a550df963345cb3574be3b0b54378bd11f14dfd515a8976f2c2d2826090e9507b8ccc24f896a9ffffffcabcfd996a733@3.129.120.128:31001"
]

# Sync configuration
sync-mode="SNAP"
data-storage-format="BONSAI"

# P2P
p2p-port=30303
p2p-host="YOUR_PUBLIC_IP" # Replace with your machine public IP
host-allowlist=["*"]
discovery-enabled=true
fast-sync-min-peers=1

# Engine API (CRITICAL for Maru connection)
engine-host-allowlist=["*"]
engine-rpc-port=8550
engine-jwt-disabled=true
engine-rpc-enabled=true # No JWT required for development/testing

# JSON-RPC
rpc-http-enabled=true
rpc-http-host="0.0.0.0"
rpc-http-port=8545
rpc-http-cors-origins=["*"]
rpc-http-api=["ENGINE","DEBUG","NET","ETH","WEB3"]

Update Besu genesis.json per the file here:

{
"config": {
"chainId": 59141,
"homesteadBlock": 0,
"eip150Block": 0,
"eip155Block": 0,
"eip158Block": 0,
"byzantiumBlock": 0,
"constantinopleBlock": 0,
"petersburgBlock": 0,
"istanbulBlock": 0,
"berlinBlock": 0,
"londonBlock": 0,
"terminalTotalDifficulty": 37331807,
"shanghaiTime": 1759147200,
"cancunTime": 1759233600,
"depositContractAddress": "0x0bdae9550159eb73559e74d27fbc989641b24c8e",
"withdrawalRequestContractAddress": "0x0e97F666F1d99A60590F7Ce7fA5A5a7C754Ff714",
"clique":{
"createemptyblocks": true,
"blockperiodseconds": 1,
"epochlength":30000
},
"blobSchedule": {
"cancun": {
"target": 0,
"max": 0,
"baseFeeUpdateFraction": 3338477
},
"prague": {
"target": 0,
"max": 0,
"baseFeeUpdateFraction": 3338477
}
}
},
"nonce": "0x0",
"timestamp": "0x6391BFF3",
"extraData": "0x0000000000000000000000000000000000000000000000000000000000000000a27342f1b74c0cfb2cda74bac1628d0c1a9752f20000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
"gasLimit": "0x3A2C940",
"baseFeePerGas": "0x8",
"difficulty": "0x1",
"mixHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
"coinbase": "0x0000000000000000000000000000000000000000",
"alloc": {
"Ed8587afbDBb2504EC31583B3377447d6fA322B2": {
"balance": "0x8AC7230489E80000"
},
"971e727e956690b9957be6d51Ec16E73AcAC83A7": {
"balance": "0x33B2E3C9FD0803CE8000000"
},
"47C63d1E391FcB3dCdC40C4d7fA58ADb172f8c38": {
"balance": "0x8AC7230489E80000"
},
"5948ccC8A59B464c6DcC87db4004Cf0a8d600C93": {
"balance": "0x8AC7230489E80000"
},
"73259D1d7534D1b68542e3240Cf76A03a5C2530F": {
"balance": "0x8AC7230489E80000"
},
"857dBFEbD7D29a75FF06d1423c418Da3b6E07292": {
"balance": "0x8AC7230489E80000"
},
"C702eAfe94b232ed50A7d4aC204306b97cdDAB0B": {
"balance": "0x8AC7230489E80000"
},
"Cc791070a5aA20f7C77CFd02E1713AfA30A23021": {
"balance": "0x8AC7230489E80000"
},
"Cd6366E24283D5D2fA10350Ac75d8a0B798E1FAe": {
"balance": "0x8AC7230489E80000"
},
"d83C3dC7257Eb2E304CBEB50b0B98bc2dd2cdCd9": {
"balance": "0x8AC7230489E80000"
},
"df5443dBe811fF9a121466dDa3C96292a3F6f43D": {
"balance": "0x8AC7230489E80000"
},
"0000000000000000000000000000000000000000": {
"balance": "0x1"
},
"0000000000000000000000000000000000000001": {
"balance": "0x1"
},
"0000000000000000000000000000000000000002": {
"balance": "0x1"
},
"0000000000000000000000000000000000000003": {
"balance": "0x1"
},
"0000000000000000000000000000000000000004": {
"balance": "0x1"
},
"0000000000000000000000000000000000000005": {
"balance": "0x1"
},
"0000000000000000000000000000000000000006": {
"balance": "0x1"
},
"0000000000000000000000000000000000000007": {
"balance": "0x1"
},
"0000000000000000000000000000000000000008": {
"balance": "0x1"
},
"0000000000000000000000000000000000000009": {
"balance": "0x1"
},
"000000000000000000000000000000000000000a": {
"balance": "0x1"
},
"000000000000000000000000000000000000000b": {
"balance": "0x1"
},
"000000000000000000000000000000000000000c": {
"balance": "0x1"
},
"000000000000000000000000000000000000000d": {
"balance": "0x1"
},
"000000000000000000000000000000000000000e": {
"balance": "0x1"
},
"000000000000000000000000000000000000000f": {
"balance": "0x1"
},
"0000000000000000000000000000000000000010": {
"balance": "0x1"
},
"0000000000000000000000000000000000000011": {
"balance": "0x1"
},
"0000000000000000000000000000000000000012": {
"balance": "0x1"
},
"0000000000000000000000000000000000000013": {
"balance": "0x1"
},
"0000000000000000000000000000000000000014": {
"balance": "0x1"
},
"0000000000000000000000000000000000000015": {
"balance": "0x1"
},
"0000000000000000000000000000000000000016": {
"balance": "0x1"
},
"0000000000000000000000000000000000000017": {
"balance": "0x1"
},
"0000000000000000000000000000000000000018": {
"balance": "0x1"
},
"0000000000000000000000000000000000000019": {
"balance": "0x1"
},
"000000000000000000000000000000000000001a": {
"balance": "0x1"
},
"000000000000000000000000000000000000001b": {
"balance": "0x1"
},
"000000000000000000000000000000000000001c": {
"balance": "0x1"
},
"000000000000000000000000000000000000001d": {
"balance": "0x1"
},
"000000000000000000000000000000000000001e": {
"balance": "0x1"
},
"000000000000000000000000000000000000001f": {
"balance": "0x1"
},
"0000000000000000000000000000000000000020": {
"balance": "0x1"
},
"0000000000000000000000000000000000000021": {
"balance": "0x1"
},
"0000000000000000000000000000000000000022": {
"balance": "0x1"
},
"0000000000000000000000000000000000000023": {
"balance": "0x1"
},
"0000000000000000000000000000000000000024": {
"balance": "0x1"
},
"0000000000000000000000000000000000000025": {
"balance": "0x1"
},
"0000000000000000000000000000000000000026": {
"balance": "0x1"
},
"0000000000000000000000000000000000000027": {
"balance": "0x1"
},
"0000000000000000000000000000000000000028": {
"balance": "0x1"
},
"0000000000000000000000000000000000000029": {
"balance": "0x1"
},
"000000000000000000000000000000000000002a": {
"balance": "0x1"
},
"000000000000000000000000000000000000002b": {
"balance": "0x1"
},
"000000000000000000000000000000000000002c": {
"balance": "0x1"
},
"000000000000000000000000000000000000002d": {
"balance": "0x1"
},
"000000000000000000000000000000000000002e": {
"balance": "0x1"
},
"000000000000000000000000000000000000002f": {
"balance": "0x1"
},
"0000000000000000000000000000000000000030": {
"balance": "0x1"
},
"0000000000000000000000000000000000000031": {
"balance": "0x1"
},
"0000000000000000000000000000000000000032": {
"balance": "0x1"
},
"0000000000000000000000000000000000000033": {
"balance": "0x1"
},
"0000000000000000000000000000000000000034": {
"balance": "0x1"
},
"0000000000000000000000000000000000000035": {
"balance": "0x1"
},
"0000000000000000000000000000000000000036": {
"balance": "0x1"
},
"0000000000000000000000000000000000000037": {
"balance": "0x1"
},
"0000000000000000000000000000000000000038": {
"balance": "0x1"
},
"0000000000000000000000000000000000000039": {
"balance": "0x1"
},
"000000000000000000000000000000000000003a": {
"balance": "0x1"
},
"000000000000000000000000000000000000003b": {
"balance": "0x1"
},
"000000000000000000000000000000000000003c": {
"balance": "0x1"
},
"000000000000000000000000000000000000003d": {
"balance": "0x1"
},
"000000000000000000000000000000000000003e": {
"balance": "0x1"
},
"000000000000000000000000000000000000003f": {
"balance": "0x1"
},
"0000000000000000000000000000000000000040": {
"balance": "0x1"
},
"0000000000000000000000000000000000000041": {
"balance": "0x1"
},
"0000000000000000000000000000000000000042": {
"balance": "0x1"
},
"0000000000000000000000000000000000000043": {
"balance": "0x1"
},
"0000000000000000000000000000000000000044": {
"balance": "0x1"
},
"0000000000000000000000000000000000000045": {
"balance": "0x1"
},
"0000000000000000000000000000000000000046": {
"balance": "0x1"
},
"0000000000000000000000000000000000000047": {
"balance": "0x1"
},
"0000000000000000000000000000000000000048": {
"balance": "0x1"
},
"0000000000000000000000000000000000000049": {
"balance": "0x1"
},
"000000000000000000000000000000000000004a": {
"balance": "0x1"
},
"000000000000000000000000000000000000004b": {
"balance": "0x1"
},
"000000000000000000000000000000000000004c": {
"balance": "0x1"
},
"000000000000000000000000000000000000004d": {
"balance": "0x1"
},
"000000000000000000000000000000000000004e": {
"balance": "0x1"
},
"000000000000000000000000000000000000004f": {
"balance": "0x1"
},
"0000000000000000000000000000000000000050": {
"balance": "0x1"
},
"0000000000000000000000000000000000000051": {
"balance": "0x1"
},
"0000000000000000000000000000000000000052": {
"balance": "0x1"
},
"0000000000000000000000000000000000000053": {
"balance": "0x1"
},
"0000000000000000000000000000000000000054": {
"balance": "0x1"
},
"0000000000000000000000000000000000000055": {
"balance": "0x1"
},
"0000000000000000000000000000000000000056": {
"balance": "0x1"
},
"0000000000000000000000000000000000000057": {
"balance": "0x1"
},
"0000000000000000000000000000000000000058": {
"balance": "0x1"
},
"0000000000000000000000000000000000000059": {
"balance": "0x1"
},
"000000000000000000000000000000000000005a": {
"balance": "0x1"
},
"000000000000000000000000000000000000005b": {
"balance": "0x1"
},
"000000000000000000000000000000000000005c": {
"balance": "0x1"
},
"000000000000000000000000000000000000005d": {
"balance": "0x1"
},
"000000000000000000000000000000000000005e": {
"balance": "0x1"
},
"000000000000000000000000000000000000005f": {
"balance": "0x1"
},
"0000000000000000000000000000000000000060": {
"balance": "0x1"
},
"0000000000000000000000000000000000000061": {
"balance": "0x1"
},
"0000000000000000000000000000000000000062": {
"balance": "0x1"
},
"0000000000000000000000000000000000000063": {
"balance": "0x1"
},
"0000000000000000000000000000000000000064": {
"balance": "0x1"
},
"0000000000000000000000000000000000000065": {
"balance": "0x1"
},
"0000000000000000000000000000000000000066": {
"balance": "0x1"
},
"0000000000000000000000000000000000000067": {
"balance": "0x1"
},
"0000000000000000000000000000000000000068": {
"balance": "0x1"
},
"0000000000000000000000000000000000000069": {
"balance": "0x1"
},
"000000000000000000000000000000000000006a": {
"balance": "0x1"
},
"000000000000000000000000000000000000006b": {
"balance": "0x1"
},
"000000000000000000000000000000000000006c": {
"balance": "0x1"
},
"000000000000000000000000000000000000006d": {
"balance": "0x1"
},
"000000000000000000000000000000000000006e": {
"balance": "0x1"
},
"000000000000000000000000000000000000006f": {
"balance": "0x1"
},
"0000000000000000000000000000000000000070": {
"balance": "0x1"
},
"0000000000000000000000000000000000000071": {
"balance": "0x1"
},
"0000000000000000000000000000000000000072": {
"balance": "0x1"
},
"0000000000000000000000000000000000000073": {
"balance": "0x1"
},
"0000000000000000000000000000000000000074": {
"balance": "0x1"
},
"0000000000000000000000000000000000000075": {
"balance": "0x1"
},
"0000000000000000000000000000000000000076": {
"balance": "0x1"
},
"0000000000000000000000000000000000000077": {
"balance": "0x1"
},
"0000000000000000000000000000000000000078": {
"balance": "0x1"
},
"0000000000000000000000000000000000000079": {
"balance": "0x1"
},
"000000000000000000000000000000000000007a": {
"balance": "0x1"
},
"000000000000000000000000000000000000007b": {
"balance": "0x1"
},
"000000000000000000000000000000000000007c": {
"balance": "0x1"
},
"000000000000000000000000000000000000007d": {
"balance": "0x1"
},
"000000000000000000000000000000000000007e": {
"balance": "0x1"
},
"000000000000000000000000000000000000007f": {
"balance": "0x1"
},
"0000000000000000000000000000000000000080": {
"balance": "0x1"
},
"0000000000000000000000000000000000000081": {
"balance": "0x1"
},
"0000000000000000000000000000000000000082": {
"balance": "0x1"
},
"0000000000000000000000000000000000000083": {
"balance": "0x1"
},
"0000000000000000000000000000000000000084": {
"balance": "0x1"
},
"0000000000000000000000000000000000000085": {
"balance": "0x1"
},
"0000000000000000000000000000000000000086": {
"balance": "0x1"
},
"0000000000000000000000000000000000000087": {
"balance": "0x1"
},
"0000000000000000000000000000000000000088": {
"balance": "0x1"
},
"0000000000000000000000000000000000000089": {
"balance": "0x1"
},
"000000000000000000000000000000000000008a": {
"balance": "0x1"
},
"000000000000000000000000000000000000008b": {
"balance": "0x1"
},
"000000000000000000000000000000000000008c": {
"balance": "0x1"
},
"000000000000000000000000000000000000008d": {
"balance": "0x1"
},
"000000000000000000000000000000000000008e": {
"balance": "0x1"
},
"000000000000000000000000000000000000008f": {
"balance": "0x1"
},
"0000000000000000000000000000000000000090": {
"balance": "0x1"
},
"0000000000000000000000000000000000000091": {
"balance": "0x1"
},
"0000000000000000000000000000000000000092": {
"balance": "0x1"
},
"0000000000000000000000000000000000000093": {
"balance": "0x1"
},
"0000000000000000000000000000000000000094": {
"balance": "0x1"
},
"0000000000000000000000000000000000000095": {
"balance": "0x1"
},
"0000000000000000000000000000000000000096": {
"balance": "0x1"
},
"0000000000000000000000000000000000000097": {
"balance": "0x1"
},
"0000000000000000000000000000000000000098": {
"balance": "0x1"
},
"0000000000000000000000000000000000000099": {
"balance": "0x1"
},
"000000000000000000000000000000000000009a": {
"balance": "0x1"
},
"000000000000000000000000000000000000009b": {
"balance": "0x1"
},
"000000000000000000000000000000000000009c": {
"balance": "0x1"
},
"000000000000000000000000000000000000009d": {
"balance": "0x1"
},
"000000000000000000000000000000000000009e": {
"balance": "0x1"
},
"000000000000000000000000000000000000009f": {
"balance": "0x1"
},
"00000000000000000000000000000000000000a0": {
"balance": "0x1"
},
"00000000000000000000000000000000000000a1": {
"balance": "0x1"
},
"00000000000000000000000000000000000000a2": {
"balance": "0x1"
},
"00000000000000000000000000000000000000a3": {
"balance": "0x1"
},
"00000000000000000000000000000000000000a4": {
"balance": "0x1"
},
"00000000000000000000000000000000000000a5": {
"balance": "0x1"
},
"00000000000000000000000000000000000000a6": {
"balance": "0x1"
},
"00000000000000000000000000000000000000a7": {
"balance": "0x1"
},
"00000000000000000000000000000000000000a8": {
"balance": "0x1"
},
"00000000000000000000000000000000000000a9": {
"balance": "0x1"
},
"00000000000000000000000000000000000000aa": {
"balance": "0x1"
},
"00000000000000000000000000000000000000ab": {
"balance": "0x1"
},
"00000000000000000000000000000000000000ac": {
"balance": "0x1"
},
"00000000000000000000000000000000000000ad": {
"balance": "0x1"
},
"00000000000000000000000000000000000000ae": {
"balance": "0x1"
},
"00000000000000000000000000000000000000af": {
"balance": "0x1"
},
"00000000000000000000000000000000000000b0": {
"balance": "0x1"
},
"00000000000000000000000000000000000000b1": {
"balance": "0x1"
},
"00000000000000000000000000000000000000b2": {
"balance": "0x1"
},
"00000000000000000000000000000000000000b3": {
"balance": "0x1"
},
"00000000000000000000000000000000000000b4": {
"balance": "0x1"
},
"00000000000000000000000000000000000000b5": {
"balance": "0x1"
},
"00000000000000000000000000000000000000b6": {
"balance": "0x1"
},
"00000000000000000000000000000000000000b7": {
"balance": "0x1"
},
"00000000000000000000000000000000000000b8": {
"balance": "0x1"
},
"00000000000000000000000000000000000000b9": {
"balance": "0x1"
},
"00000000000000000000000000000000000000ba": {
"balance": "0x1"
},
"00000000000000000000000000000000000000bb": {
"balance": "0x1"
},
"00000000000000000000000000000000000000bc": {
"balance": "0x1"
},
"00000000000000000000000000000000000000bd": {
"balance": "0x1"
},
"00000000000000000000000000000000000000be": {
"balance": "0x1"
},
"00000000000000000000000000000000000000bf": {
"balance": "0x1"
},
"00000000000000000000000000000000000000c0": {
"balance": "0x1"
},
"00000000000000000000000000000000000000c1": {
"balance": "0x1"
},
"00000000000000000000000000000000000000c2": {
"balance": "0x1"
},
"00000000000000000000000000000000000000c3": {
"balance": "0x1"
},
"00000000000000000000000000000000000000c4": {
"balance": "0x1"
},
"00000000000000000000000000000000000000c5": {
"balance": "0x1"
},
"00000000000000000000000000000000000000c6": {
"balance": "0x1"
},
"00000000000000000000000000000000000000c7": {
"balance": "0x1"
},
"00000000000000000000000000000000000000c8": {
"balance": "0x1"
},
"00000000000000000000000000000000000000c9": {
"balance": "0x1"
},
"00000000000000000000000000000000000000ca": {
"balance": "0x1"
},
"00000000000000000000000000000000000000cb": {
"balance": "0x1"
},
"00000000000000000000000000000000000000cc": {
"balance": "0x1"
},
"00000000000000000000000000000000000000cd": {
"balance": "0x1"
},
"00000000000000000000000000000000000000ce": {
"balance": "0x1"
},
"00000000000000000000000000000000000000cf": {
"balance": "0x1"
},
"00000000000000000000000000000000000000d0": {
"balance": "0x1"
},
"00000000000000000000000000000000000000d1": {
"balance": "0x1"
},
"00000000000000000000000000000000000000d2": {
"balance": "0x1"
},
"00000000000000000000000000000000000000d3": {
"balance": "0x1"
},
"00000000000000000000000000000000000000d4": {
"balance": "0x1"
},
"00000000000000000000000000000000000000d5": {
"balance": "0x1"
},
"00000000000000000000000000000000000000d6": {
"balance": "0x1"
},
"00000000000000000000000000000000000000d7": {
"balance": "0x1"
},
"00000000000000000000000000000000000000d8": {
"balance": "0x1"
},
"00000000000000000000000000000000000000d9": {
"balance": "0x1"
},
"00000000000000000000000000000000000000da": {
"balance": "0x1"
},
"00000000000000000000000000000000000000db": {
"balance": "0x1"
},
"00000000000000000000000000000000000000dc": {
"balance": "0x1"
},
"00000000000000000000000000000000000000dd": {
"balance": "0x1"
},
"00000000000000000000000000000000000000de": {
"balance": "0x1"
},
"00000000000000000000000000000000000000df": {
"balance": "0x1"
},
"00000000000000000000000000000000000000e0": {
"balance": "0x1"
},
"00000000000000000000000000000000000000e1": {
"balance": "0x1"
},
"00000000000000000000000000000000000000e2": {
"balance": "0x1"
},
"00000000000000000000000000000000000000e3": {
"balance": "0x1"
},
"00000000000000000000000000000000000000e4": {
"balance": "0x1"
},
"00000000000000000000000000000000000000e5": {
"balance": "0x1"
},
"00000000000000000000000000000000000000e6": {
"balance": "0x1"
},
"00000000000000000000000000000000000000e7": {
"balance": "0x1"
},
"00000000000000000000000000000000000000e8": {
"balance": "0x1"
},
"00000000000000000000000000000000000000e9": {
"balance": "0x1"
},
"00000000000000000000000000000000000000ea": {
"balance": "0x1"
},
"00000000000000000000000000000000000000eb": {
"balance": "0x1"
},
"00000000000000000000000000000000000000ec": {
"balance": "0x1"
},
"00000000000000000000000000000000000000ed": {
"balance": "0x1"
},
"00000000000000000000000000000000000000ee": {
"balance": "0x1"
},
"00000000000000000000000000000000000000ef": {
"balance": "0x1"
},
"00000000000000000000000000000000000000f0": {
"balance": "0x1"
},
"00000000000000000000000000000000000000f1": {
"balance": "0x1"
},
"00000000000000000000000000000000000000f2": {
"balance": "0x1"
},
"00000000000000000000000000000000000000f3": {
"balance": "0x1"
},
"00000000000000000000000000000000000000f4": {
"balance": "0x1"
},
"00000000000000000000000000000000000000f5": {
"balance": "0x1"
},
"00000000000000000000000000000000000000f6": {
"balance": "0x1"
},
"00000000000000000000000000000000000000f7": {
"balance": "0x1"
},
"00000000000000000000000000000000000000f8": {
"balance": "0x1"
},
"00000000000000000000000000000000000000f9": {
"balance": "0x1"
},
"00000000000000000000000000000000000000fa": {
"balance": "0x1"
},
"00000000000000000000000000000000000000fb": {
"balance": "0x1"
},
"00000000000000000000000000000000000000fc": {
"balance": "0x1"
},
"00000000000000000000000000000000000000fd": {
"balance": "0x1"
},
"00000000000000000000000000000000000000fe": {
"balance": "0x1"
},
"00000000000000000000000000000000000000ff": {
"balance": "0x1"
}
},
"number": "0x0",
"gasUsed": "0x0",
"parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000"
}

Step 3: Maru configuration (follower node)

Create maru/config/maru-config.toml:

# IMPORTANT: No [qbft] section = follower node (not validator)

[linea]
contract-address = "0xB218f8A4Bc926cF1cA7b3423c154a0D627Bdb7E5"
l1-eth-api = { endpoint = "<your Sepolia RPC endpoint>" }
l1-polling-interval = "6 seconds"
l1-highest-block-tag = "finalized"

[persistence]
data-path = "/opt/maru/data"
private-key-path = "/opt/maru/private-key"

[p2p]
port = 9000 # Default port (can be same as discovery)
ip-address = "0.0.0.0"
static-peers = ["/ip4/3.129.120.128/tcp/31005/p2p/16Uiu2HAmR33t8RZiAHovuH9iH2UuUrajrbfyYowiYDAQo3D5Y9wg", "/ip4/3.129.120.128/tcp/31006/p2p/16Uiu2HAm9HB5oNmnmj8yY6T7dfhLVidVzYqa8QVDtEthkMr6b8tx"]
reconnect-delay = "500ms"

[p2p.discovery]
port = 9000
bootnodes = []
refresh-interval = "3s"

[payload-validator]
engine-api-endpoint = { endpoint = "http://linea-besu:8550" } # Match Besu port!
eth-api-endpoint = { endpoint = "http://linea-besu:8545" }

[observability]
port = 9090
jvm-metrics-enabled = true
prometheus-metrics-enabled = true

[api]
port = 8080

[syncing]
peer-chain-height-polling-interval = "5s"
el-sync-status-refresh-interval = "5s"
sync-target-selection = "Highest"
desync-tolerance = 0

[syncing.download]
block-range-request-timeout = "10s"
blocks-batch-size = 10
blocks-parallelism = 10
max-retries = 5
backoff-delay = "1s"
use-unconditional-random-download-peer = false

Step 4: Maru genesis file

Create maru/config/maru-genesis.json:

{
"chainId": 59141,
"config": {
"0": {
"type": "difficultyAwareQbft",
"blockTimeSeconds": 2,
"postTtdConfig": {
"validatorSet": ["0xb4323e9d9998990e6333293f8f0d2d09d1619328"],
"elFork": "Paris"
},
"terminalTotalDifficulty": 37331807
},
"1759147200": {
"type": "qbft",
"validatorSet": ["0xb4323e9d9998990e6333293f8f0d2d09d1619328"],
"blockTimeSeconds": 2,
"elFork": "Shanghai"
},
"1759233600": {
"type": "qbft",
"validatorSet": ["0xb4323e9d9998990e6333293f8f0d2d09d1619328"],
"blockTimeSeconds": 2,
"elFork": "Cancun"
}
}
}

Step 5: Docker Compose setup

Create docker-compose.yml:

networks:
linea: {}

services:
besu:
image: hyperledger/besu:25.8.0
container_name: linea-besu
restart: unless-stopped
networks: [linea]
ports:
- "8545:8545" # JSON-RPC
- "8550:8550" # Engine API
- "30303:30303" # P2P TCP
- "30303:30303/udp" # P2P UDP
environment:
- JAVA_OPTS=-Xmx4g
volumes:
- ./besu/data:/opt/besu/data
- ./besu/config/config.toml:/opt/besu/config.toml:ro
- ./besu/genesis.json:/opt/besu/genesis.json:ro
command:
- --config-file=/opt/besu/config.toml

maru:
image: consensys/maru:2a2eab0
container_name: linea-maru
restart: unless-stopped
depends_on:
- besu
networks: [linea]
ports:
- "8080:8080" # Beacon/REST API
- "9000:9000/tcp" # P2P main port
- "9000:9000/udp" # P2P discovery port (UDP only)
- "9090:9090" # Metrics optionnal
environment:
- JAVA_OPTS=-Xmx2g
volumes:
- ./maru/config:/opt/consensys/maru/configs:ro
- ./maru/data:/data
command:
- "java"
- "-Dlog4j2.configurationFile=/opt/consensys/maru/configs/log4j.xml"
- "-jar"
- "/opt/consensys/maru/maru.jar"
- "--maru-genesis-file"
- "/opt/consensys/maru/configs/maru-genesis.json"
- "--config"
- "/opt/consensys/maru/configs/maru-config.toml"

Step 6: Launch and verify

# Start both services (Besu first then Maru)
docker-compose up -d

# Check Besu is syncing
curl -X POST http://localhost:8545 -H "Content-Type: application/json" \
-d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'

# Check Maru health
curl -X GET "http://localhost:8080/eth/v1/node/health"

# Verify P2P connection
docker logs linea-maru | grep "Currently connected peers"
# Should show: peers=[16Uiu2HAmR33t8RZiAHovuH9iH2UuUrajrbfyYowiYDAQo3D5Y9wg]

JWT Authentication

For production environments, you should enable JWT authentication:

Generate JWT secret

openssl rand -hex 32 > ~/linea-node/jwt/jwt.hex

Update Besu config

# Replace engine-jwt-disabled=true with:
engine-jwt-enabled=true
engine-jwt-file="/opt/besu/jwt.hex"

Update Maru config

[payload-validator]
engine-api-endpoint = { endpoint = "http://linea-besu:8550", jwt-secret-path = "/jwt.hex" }

Update Docker volumes

# Add to both Besu and Maru:
volumes:
- ./jwt/jwt.hex:/jwt.hex:ro

Private key management

Development: Maru auto-generates private keys at startup if none exist. (TBC)

Production: Generate and backup your private key (not mandatory):

# Option 1: Let Maru auto-generate, then backup:
docker cp linea-maru:/data/private-key ./backup/

# Option 2: Generate using Maru's key generation tool:
# https://github.com/Consensys/maru/tree/main/jvm-libs/utils
Important

Maintaining the same private key preserves node identity across restarts.

Troubleshooting

Debug commands

# EL client block height
curl -s -X POST http://localhost:8545 -H "Content-Type: application/json" \
-d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'

# Maru health
curl http://localhost:8080/eth/v1/node/health

# Check block headers
curl http://localhost:8080/eth/v1/beacon/headers/head