Installation

Docker (recommended)

Docker Compose runs the full stack: the Arbitrum Reth execution client plus the Nitro consensus node that drives block production.

A prebuilt multi-arch image (linux/amd64 and linux/arm64) is published for every release at ghcr.io/0xbloctopus/arbitrum-reth. docker compose up -d pulls and runs that image by default. Use docker compose up -d --build to build the image from source instead.

Syncing Arbitrum Sepolia from genesis takes time. To start from a recent state instead, download a datadir snapshot first. See Snapshots.

git clone https://github.com/0xBloctopus/arbitrum-reth.git
cd arbitrum-reth
cp .env.example .env

Edit .env to set your Ethereum Sepolia L1 endpoints:

PARENT_CHAIN_RPC_URL=<ethereum-sepolia-rpc>
PARENT_CHAIN_BEACON_URL=<ethereum-sepolia-beacon>

Start the stack:

docker compose up -d

Arbitrum Reth starts syncing Arbitrum Sepolia (chain id 421614). Nitro waits for the execution client to pass its healthcheck before starting.

Verify sync progress

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

View logs

docker compose logs -f arbitrum-reth    # execution client
docker compose logs -f nitro            # consensus node

Stop

docker compose down

Data persists in the volumes (arbitrum-reth-data, nitro-data) and survives restarts.

Build from Source

Requirements

• Rust 1.93 or later
• clang and libclang-dev
• cmake

Build

git clone https://github.com/0xBloctopus/arbitrum-reth.git
cd arbitrum-reth
git submodule update --init --recursive
cargo build --release -p arb-reth

The submodule step fetches the brotli and Nitro interface dependencies; the build fails without it. The binary lands at ./target/release/arb-reth.

Run

The execution client and Nitro authenticate to each other with a shared JWT secret:

openssl rand -hex 32 > /path/to/jwt.hex

Start the node:

./target/release/arb-reth node \
  --chain=genesis/arbitrum-sepolia.json \
  --datadir=/path/to/data \
  --http \
  --http.addr=0.0.0.0 \
  --http.api=eth,web3,net,debug \
  --authrpc.addr=0.0.0.0 \
  --authrpc.jwtsecret=/path/to/jwt.hex

Ports

Nitro connects on port 8551 with the shared JWT and drives block production over the nitroexecution_ RPC namespace (nitroexecution_digestMessage), not the Engine API.

Running the Consensus Node

Arbitrum Reth is an execution client only. It needs Nitro to ingest L1 messages and drive block production. To run Nitro standalone:

docker run offchainlabs/nitro-node:v3.10.0-rc.10-b1cf6db \
  --init.empty=true \
  --init.validate-genesis-assertion=false \
  --parent-chain.connection.url=<ethereum-sepolia-rpc> \
  --parent-chain.blob-client.beacon-url=<ethereum-sepolia-beacon> \
  --chain.id=421614 \
  --node.execution-rpc-client.url=http://HOST:8551 \
  --node.execution-rpc-client.jwtsecret=/path/to/jwt.hex \
  --node.sequencer=false \
  --node.feed.input.url=wss://sepolia-rollup.arbitrum.io/feed

Compose sets this image to offchainlabs/nitro-node:v3.10.0-rc.10-b1cf6db by default; override it with the NITRO_IMAGE variable in .env. The bundled docker-compose.yml wires this up automatically.