How to Run a Sequencer Node

Background

The Aztec sequencer node is critical infrastructure responsible for ordering transactions and producing blocks.

The sequencer node takes part in three key actions:

1. Assemble unprocessed transactions and propose the next block
2. Attest to correct execution of txs in the proposed block (if part of validator committee)
3. Submit the successfully attested block to L1

When transactions are sent to the Aztec network, sequencer nodes bundles them into blocks, checking various constraints such as gas limits, block size, and transaction validity. Before a block can be published, it must be validated by a committee of other sequencer nodes (validators in this context) who re-execute public transactions and verify private function proofs so they can attest to correct execution. These validators attest to the block's validity by signing it, and once enough attestations are collected (two-thirds of the committee plus one), the sequencer can submit the block to L1.

The archiver component complements this process by maintaining historical chain data. It continuously monitors L1 for new blocks, processes them, and maintains a synchronized view of the chain state. This includes managing contract data, transaction logs, and L1-to-L2 messages, making it essential for network synchronization and data availability.

Setup

Requirements

A computer running Linux or MacOS with the following specifications:

• CPU: 8-cores
• RAM: 16 GiB
• Storage: 1 TB SSD
• Network: A connection of at least 25 Mbps up/down

Installation

To use Aztec's suite of tools you'll need to:

1. Get docker (engine or desktop)
2. Run bash -i <(curl -s https://install.aztec.network)

Now install the latest testnet version of aztec:

aztec-up -v latest

Join the Discord to connect with the community and get help with your setup.

Sequencer Quickstart

With the alpha-testnet version of the aztec tools, you now need to define required variables for your node.

The following variable names are specific to the aztec start command, set them as variables in the terminal or inline before the command.

• ETHEREUM_HOSTS=<url>: One or more comma-separated public rpc provider url(s). NB - don't share your access token
• L1_CONSENSUS_HOST_URLS=<url>: One or more comma-separated public rpc provider url(s) that supports consensus client requests
• VALIDATOR_PRIVATE_KEY="0x<hex value>": Private key of testnet L1 EOA that holds Sepolia ETH (0.01 Sepolia ETH can get you started)
• COINBASE="0x<eth address>": Recipient of block rewards (for node security on mainnet, this should be a different address to the validator eoa)
• P2P_IP="x.x.x.x": IP address of computer running the node (you can get this by running curl api.ipify.org on your node)

Now in a terminal start your node as a sequencer and archiver:

If the above variables are set you can simply use:

aztec start --node --archiver --sequencer --network alpha-testnet

Otherwise you can specify values via the CLI flags (using values in place of the variable names):

aztec start --node --archiver --sequencer \
  --network alpha-testnet \
  --l1-rpc-urls $ETHEREUM_HOSTS \
  --l1-consensus-host-urls $L1_CONSENSUS_HOST_URLS \
  --sequencer.validatorPrivateKey $VALIDATOR_PRIVATE_KEY \
  --sequencer.coinbase $COINBASE \
  --p2p.p2pIp $P2P_IP

Additional Parameters: The comprehensive list of parameters can be seen via: aztec help start. For example:

--p2p.p2pPort <value>        (default: 40400)        ($P2P_PORT)
      The port for the P2P service.

Port forwarding

For some restricted environments, you may need to explicitly forward the p2p port (default: 40400) to your local node ip address.

This is often in a router's advanced network settings if required.

Next steps

To add your sequencer you'll need the following few values, as well as ETHEREUM_HOSTS from before:

• STAKING_ASSET_HANDLER="0xF739D03e98e23A7B65940848aBA8921fF3bAc4b2": Constant L1 contract address
• L1_CHAIN_ID="11155111": Sepolia chainid
• PRIVATE_KEY="0x<hex value>": private key of account with sepolia eth to make transaction (eg can use funded validator key)

Then run the aztec command to add your address as an L1 validator, with rpc url(s) for Ethereum L1 execution requests:

aztec add-l1-validator --staking-asset-handler=0xF739D03e98e23A7B65940848aBA8921fF3bAc4b2 \
  --l1-rpc-urls $ETHEREUM_HOSTS \
  --l1-chain-id 11155111 \
  --private-key "0x<hex value>" \
  --attester "0x<eth address>" \
  --proposer-eoa "0x<eth address>"

astuce

Use aztec help add-l1-validator for further parameter details.

Validator Quota Filled

In the absence of real-world staking incentives, becoming a validator is throttled with time, so you may see ValidatorQuotaFilledUntil(uint256 _timestamp) at the beginning of the text returned.

The timestamp is when the next round of sequencers can be added as validators, so try again right after that.

Deeper dive

This guide will describe how to setup your sequencer using the aztec start command. For more advanced setups, refer to the Advanced Configuration section below.

The aztec start tool is a one-stop-shop for running your sequencer on any Aztec Network. It assigns default values to several config variables based on a --network flag and launches a docker container running the sequencer software.

To use the aztec start command, you need to obtain the following:

RPCs

An L1 execution client (for reading transactions and state). It can be specified via the --l1-rpc-urls flag when using aztec start or via the env var ETHEREUM_HOSTS. Popular execution clients include Geth or Nethermind. You can run your own node or use a service like Alchemy or Infura.

An L1 consensus client (for blobs). It can be specified via the --l1-consensus-host-urls flag when using aztec start or via the env var L1_CONSENSUS_HOST_URLS. Popular consensus clients include Lighthouse or Prysm. Not all RPC providers support consensus endpoints, Quicknode and dRPC have been known to work for consensus endpoints.

To reduce load on your consensus endpoint, the Aztec sequencer supports an optional remote server that serves blobs to the client. This is often called a "blob sink" or "blob storage service". You can pass your own or use one provided by a trusted party via the --sequencer.blobSinkUrl flag when using aztec start, or via the env var BLOB_SINK_URL. Some providers like Alchemy offer blob storage services as part of their infrastructure offerings.

Ethereum Keys

You will need an Ethereum private key and the corresponding public address. The private key is set via the --sequencer.validatorPrivateKey flag while the public address should be specified via the --sequencer.coinbase flag.

The private key is needed as your validator will post blocks to Ethereum, and the public address will be the recipient of any block rewards.

Disclaimer

You may want to generate and use a new Ethereum private key.

Networking

You MUST forward your ports. Your router must send UDP and TCP traffic on port 40400 (unless you changed the default) to your IP address on your local network. Failure to do so may result in your sequencer not participating on the p2p network.

As a tip, configure your router to give your MAC address the same IP address every time it does a DHCP refresh.

You also need to grab your external IP address and pass it along to the --p2p.p2pIp when using aztec start.

Sepolia ETH

You'll need Sepolia ETH to cover gas costs. Here are some options:

• Use a PoW faucet like Sepolia PoW Faucet
• Ask in our Discord community (and remember to pay it forward when you can!)

Now Start Your Sequencer

To boot up a sequencer using aztec start, run the following command:

aztec start --node --archiver --sequencer \
  --network alpha-testnet \
  --l1-rpc-urls https://example.com \
  --l1-consensus-host-urls https://example.com \
  --sequencer.validatorPrivateKey 0xYourPrivateKey \
  --sequencer.coinbase 0xYourAddress \
  --p2p.p2pIp 999.99.999.99 \
  --p2p.maxTxPoolSize 1000000000

astuce

For a full overview of all available commands, check out the CLI reference sheet.

astuce

If you are unable to determine your public ip. Running the command curl ipv4.icanhazip.com can retrieve it for you.

Register as a Validator

Once your node is fully synced, you can register as a validator using the add-l1-validator command:

aztec add-l1-validator \
  --l1-rpc-urls https://eth-sepolia.g.example.com/example/your-key \
  --private-key your-private-key \
  --attester your-validator-address \
  --proposer-eoa your-validator-address \
  --staking-asset-handler 0xF739D03e98e23A7B65940848aBA8921fF3bAc4b2 \
  --l1-chain-id 11155111

attention

You may see a warning when trying to register as a validator. To maintain network health there is a daily quota for validators to join the validator set. If you are not able to join, it could mean that today's quota of validators has already been added to the set. If you see this, you can try again later. Read our blog post for more info.

Advanced Configuration

Using Environment Variables

Every flag in the aztec start command corresponds to an environment variable. You can see the variable names by running aztec start --help. A reference is provided here.

For example:

• --l1-rpc-urls maps to ETHEREUM_HOSTS
• --l1-consensus-host-urls maps to L1_CONSENSUS_HOST_URLS

You can create a .env file with these variables:

ETHEREUM_HOSTS=https://example.com
L1_CONSENSUS_HOST_URLS=https://example.com
# Add other configuration variables as needed

Then source this file before running your command:

source .env
aztec start --network alpha-testnet --archiver --node --sequencer # other flags...

Using a Docker Compose

If you would like to run in a docker compose, you can use a configuration like the one below:

name: aztec-node
services:
  node:
    network_mode: host # Optional, run with host networking
    image: aztecprotocol/aztec:latest
    environment:
      ETHEREUM_HOSTS: ""
      L1_CONSENSUS_HOST_URLS: ""
      DATA_DIRECTORY: /data
      VALIDATOR_PRIVATE_KEY: $VALIDATOR_PRIVATE_KEY
      P2P_IP: $P2P_IP
      LOG_LEVEL: debug
    entrypoint: >
      sh -c 'node --no-warnings /usr/src/yarn-project/aztec/dest/bin/index.js start --network alpha-testnet --node --archiver --sequencer'
    ports:
      - 40400:40400/tcp
      - 40400:40400/udp
      - 8080:8080
    volumes:
      - /home/my-node/node:/data # Local directory

Troubleshooting

L1 Access

If you're hosting your own Ethereum execution or consensus client locally (rather than using an external RPC like Alchemy), you need to ensure that the prover node inside Docker can reach it.

By default, Docker runs containers on a bridge network that isolates them from the host machine's network interfaces. This means localhost inside the container won't point to the host's localhost.

To fix this:

Option 1: Use the special hostname host.docker.internal This tells Docker to route traffic from the container to the host machine. For example:

--l1-rpc-urls http://host.docker.internal:8545

Option 2: Add a host network entry to your Docker Compose file (advanced users) This gives your container direct access to the host's network stack, but removes Docker's network isolation. Add to your docker-compose.yml:

network_mode: "host"

Note

network_mode: "host" only works on Linux. On macOS and Windows, use host.docker.internal.

info

You can run your own Sepolia ETH Node. However, at the moment only geth and reth nodes are confirmed to work reliably with the Aztec client.

Once you have your node running, head to the Aztec Discord to interact with other network operators.

Happy sequencing!