Running an Espresso Node
Information on the different ways to run an Espresso node. The Espresso node is referred to as a 'sequencer node' from here on forth.
Basic Usage
Visit the espresso-sequencer repository for instructions on how to run a sequencer node natively or with docker. Find the latest docker images here.
Usage:
For brevity, we will omit the full sequencer path from here and simply refer to the executable as sequencer
going forward.
The sequencer docker compose file is a great reference point for configuring an entire local sequencer network, including a few sequencer nodes, an L1 client, and the HotShot data availability and orchestrator servers.
Required Parameters
Env Variable | CLI Flag | Description |
---|---|---|
ESPRESSO_SEQUENCER_L1_PROVIDER | --l1-provider-url | JSON-RPC URI of the L1 provider (e.g. http://localhost:8545. |
ESPRESSO_SEQUENCER_ORCHESTRATOR_URL | --orchestrator-url | URL of the HotShot orchestrator. This service will be provided by Espresso. |
ESPRESSO_SEQUENCER_CDN_ENDPOINT | --cdn-endpoint | The CDN's entrypoint in |
ESPRESSO_SEQUENCER_STATE_RELAY_SERVER_URL | --state-relay-server-url | URL of the state relay web server. This service will be provided by Espresso. |
ESPRESSO_SEQUENCER_STATE_PEERS | --state-peers | Comma-separated list of peer URLs to use for catchup. This may include the archival query service operated by Espresso as well as URLs of your own nodes (see catchup) |
ESPRESSO_SEQUENCER_KEY_FILE | --key-file | Path to file containing private signing keys. See key management. |
ESPRESSO_SEQUENCER_GENESIS_FILE | --genesis-file | Path to file containing genesis state. See genesis file. |
Optional Parameters
Env Variable | CLI Flag | Description |
---|---|---|
ESPRESSO_SEQUENCER_PRIVATE_STAKING_KEY | --private-staking-key | The private staking key to use for signing consensus messages. This parameter replaces the required |
ESPRESSO_SEQUENCER_PRIVATE_STATE_KEY | --private-state-key | The private key to use for signing finalized consensus states. See also |
ESPRESSO_SEQUENCER_IS_DA | --is-da | Whether or not to register for and participate in the the DA committee. |
ESPRESSO_SEQUENCER_L1_EVENTS_MAX_BLOCK_RANGE | --l1-events-max-block-range | Maximum number of blocks allowed in a single |
ESPRESSO_SEQUENCER_LIBP2P_BIND_ADDRESS | --libp2p-bind-address | [If Libp2p is enabled] The address to bind Libp2p to in |
ESPRESSO_SEQUENCER_LIBP2P_ADVERTISE_ADDRESS | --libp2p-advertise-address | [If Libp2p is enabled] The address we should advertise to other nodes as being our Libp2p endpoint (in |
ESPRESSO_SEQUENCER_LIBP2P_BOOTSTRAP_NODES | --libp2p-bootstrap-nodes | [If Libp2p is enabled] A comma separated list of well-known peers to use to bootstrap the initial Libp2p connection. If supplied, it will override values from the orchestrator as well as those persistently saved to any config. Addresses need to be supplied in Multiaddress Format. |
[Libp2p] Multiaddress Format
Multiaddresses are a self-describing format that allow us to support a wide variety of protocols and address types. More information can be found here.
Here is an example of an address that represents a node on localhost
on port 2000
:
You can also repesent a fully qualified domain name using this format:
Notice how for both we have appended the node's public key as part of the address scheme. You can get your own Libp2p node's public key by using the dockerized public key tool:
Your Libp2p key will then be printed to the console.
Genesis File
The genesis file is used to store settings that must be identical between all nodes, like the genesis state and parameters that impact the (in)validity of proposed blocks. Genesis files for all officially supported networks are bundled with the official Docker image, making it easy to distribute the configuration and ensure it is the same across all nodes:
This docker image can be configured to run a node for any supported network simply by setting the genesis file path appropriately. For example, the local docker-compose demo uses ESPRESSO_SEQUENCER_GENESIS_FILE=/genesis/demo.toml
. It is also possible to run a node for a custom network by defining your own genesis, mounting it via a volume, and pointing the node at the mounted path.
Format
The genesis file is a TOML file with the following sections:
[chain_config]
— Parameters of the state transition function of the Espresso chain.chain_id
— Identifier for this instance of an Espresso chain.base_fee
— Fee per byte of data sequenced.max_block_size
— Maximum block size allowed to be sequenced.fee_recipient
— Address used to track amount of fees paid.fee_contract
— Address of L1 contract used to deposit fee tokens.
[l1_finalized]
— Description of the finalized L1 block from which to process L1 events.[stake_table]
— Parameters for the Espresso stake table.capacity
— The maximum number of distinct public keys.
[network]
— Configuration for connecting to the peer-to-peer network.bootstrap_nodes
— List of peers to bootstrap a P2P connection.
[accounts]
— Prefunded fee accounts, for testing purposes only.
The [chain_config]
section
[chain_config]
sectionThis section defines parameters which affect how proposed blocks are validated and how they effect the Espresso state.
All fields except fee_contract
are required.
The chain_id
field
chain_id
fieldThe Espresso chain ID is a unique identifier for a given instance of the Espresso network. Since it is part of the chain config, and the chain config is hashed into each block header, an untrusting client can check whether a block it is looking at belongs to the chain with a certain ID, which prevents attacks where a malicious server provides valid blocks from the wrong chain.
The chain ID is also used for certain protocol transactions to prevent cross-chain replay transactions, as in other blockchains like EVM-based chains. Note, however, that the most common type of transaction — rollups submitting data to be sequenced — does not reference an Espresso chain ID, since rollups will have their own globally unique chain IDs to prevent cross-chain attacks.
The base_fee
field
base_fee
fieldThe base fee is the amount of Ether required to sequence a byte of data. These sequencing fees are paid by builders submitting blocks to be finalized by consensus, and are intended to offset the cost of operating the network. Note that fees are not currently distributed to node operators, but are collected in a burner address.
The base fee can be given as a number, decimal string, or hexadecimal string (with 0x
prefix), indicating an amount in WEI. It may also be specified as a string containing a decimal number and a unit. Allowed units are wei
, gwei
, and eth
.
The max_block_size
field
max_block_size
fieldThe maximum size of a block. Honest nodes will reject a proposed block whose payload exceeds this size. This is intended as a failsafe in case the base_fee
does not adequately disincentivize DOS attacks from submitting very large blocks. This parameter may be removed in the future, when the network is upgraded to use a more sophisticated, dynamic pricing model.
The maximum block size can be given as an integer (indicating a number of bytes) or a string with a number and a unit suffix. Allowed units consist of an SI prefix k
, m
, g
, t
, p
, e
(though you will likely never have use of prefixes larger than mega), an optional i
indicating a binary system (factors of 1024 instead of 1000) and an optional b
suffix. All of these are valid units: KiB
, kb
, KB
, k
.
The fee_recipient
field
fee_recipient
fieldAn address that receives all sequencing fees.
The fee_contract
field
fee_contract
fieldThe address of a contract on the L1 chain which allows users and builders to deposit ETH into the Espresso state. The deposited tokens can then be used for paying sequencing fees.
This field may be omitted, in which case deposits are disabled. In this case, builders can still propose if
They are proposing an empty block, or
The
base_fee
is set to 0, orThey have been funded in the genesis block
The [header]
section
[header]
sectionThis section provides some inputs that will be used to construct the genesis header.
All fields are required.
The timestamp
field
timestamp
fieldThe timestamp which will be included in the genesis header. For all blocks after genesis, the timestamp is calculated dynamically, based on the system time of the proposing node. But the genesis header, and thus its timestamp, must be known to all nodes to even start proposing and validating blocks, so it must be configured.
The timestamp is given as an RFC 3339 string.
The [l1_finalized]
section
[l1_finalized]
sectionThis section determines the finalized L1 block from which Espresso will start processing events (like deposit events). The first block proposed by Espresso will process all events from the genesis l1_finalized
block to the current finalized block, so this block should be recent enough that all thoes events can be processed within the consensus view timeout. Subsequent blocks will process events incrementally from the previous finalized L1 block to the current one.
If the L1 finalized block has not yet been finalized when a node is started, the node will wait for it to be finalized before starting consensus.
If all fields are specified, the node will only accept the exact block described. If only number
is specified, the node will fetch the details of that block using its L1 provider.
The number
field
number
fieldThe block number of the finalized L1 block to use at Espresso genesis.
This field is required.
The timestamp
field
timestamp
fieldThe timestamp of the finalized L1 block to use at Espresso genesis.
This field may be omitted, in which case the timestamp will be fetched from the block indicated by number
. Note that if timestamp
is omitted, all other details must be omitted as well, and all details will be fetched based on number
.
The hash
field
hash
fieldThe hash of the finalized L1 block to use at Espresso genesis.
This field may be omitted, in which case the hash will be fetched from the block indicated by number
. Note that if hash
is omitted, all other details must be omitted as well, and all details will be fetched based on number
.
The [stake_table]
section
[stake_table]
sectionThis section configures the layout of the Espresso stake table. Note that this does not actually define the stake table. Currently the stake table is defined via the orchestrator service that nodes register with when they come online. Eventually, it will be defined by an L1 contract. This section of the genesis file only configures how the stake table is represented as a Merkle tree for proving purposes.
The capacity
field
capacity
fieldThe maximum number of distinct nodes which can be represented by the stake table. After genesis, this can only be expanded with a network upgrade.
The [accounts]
section
[accounts]
sectionUse in testing environments only.
This section allows the definition of some prefunded accounts, for paying sequencing fees. This is useful for easily setting up a testing environment where a builder has enough funds to build blocks. However, this section must only be used in testing. Since the resulting funds are created by fiat instead of being bridged from L1, they do not actually correspond to tokens locked in the bridge contract on L1, and thus use of this section can cause the bridge contract to become insolvent.
The body of this section is a list of key-value pairs, where the keys are addresses and the values indicate the balance of those accounts at Espresso genesis. The balances can be given as numbers, decimal strings, or hexadecimal strings (representing an amount in WEI), or as strings containing a decimal number and a unit. Allowed units are wei
, gwei
, and eth
.
Optional Modules
The sequencer node supports a set of optional modules that extend the node with useful APIs (e.g. transaction submission or query functionality). Here we describe what these modules do and how to enable them.
In general, modules are enabled in the following way:
HTTP
This module runs a basic HTTP server that comes with healthcheck and version endpoints. Additional endpoints can be enabled with the modules listed below.
Usage:
Parameters:
Env Variable | CLI Flag | Description |
---|---|---|
ESPRESSO_SEQUENCER_API_PORT | --port | Port that the HTTP API will use. |
ESPRESSO_SEQUENCER_MAX_CONNECTIONS | --max-connections | Maximum number of concurrent HTTP connections that the server will allow. E.g. 100. |
Status
This module extends the HTTP API with telemetry and consensus metrics (e.g. an endpoint to retrieve the latest block height).
Usage:
This will add a Prometheus endpoint GET /status/metrics
containing useful metrics for monitoring the performance of the node and network. See also monitoring.
Catchup
This module extends the HTTP API with a module that serves queries for pending consensus state. Other nodes can connect to this API to quickly sync with the latest state in the event that they fall out of sync with consensus.
Usage:
Config
This module extends the HTTP API with a module that provides the node config information. This will add two GET endpoints : /config/hotshot
and /config/env
.
Usage:
The /hotshot
endpoint retrieves the Hotshot config for the current node, excluding the private keys.
The /env
endpoint outputs all Espresso environment variables set for the current node. The keys for these variables are defined in the public-env-vars.toml
file in the crates/sequencer/api
directory.
Query
This module enables a HotShot query service API that connects to a persistent store containing the history of the blockchain. This API provides endpoints that rollups can use to integrate with the sequencer.
This module must be enabled alongside the http
module. The query API can be accessed at the port specified by the http
module. This option also requires a storage module, which defaults to storage-fs
(see below for more details on storage options).
Usage:
Env Variable | CLI Flag | Description |
---|---|---|
ESPRESSO_SEQUENCER_API_PEERS | --peers | A comma-separated list of peer query service URLs to fetch missing data from. |
Filesystem Storage
This module enables a local storage backend for the query service and consensus state. Eventually, the backend will also store DA blocks and VID shares. This setting is useful for testing and debugging, but is not recommended for production nodes because it is currently not very stable or performant. Long term, we hope to improve this storage option.
Usage:
Parameters:
Env Variable | CLI Flag | Description |
---|---|---|
ESPRESSO_SEQUENCER_STORAGE_PATH | --path | Storage path for persistent data. |
SQL Storage
This module enables a postgres storage backend for the query service and consensus state. Eventually, the backend will also store DA blocks and VID shares. This setting is recommended for production nodes.
Usage:
Parameters:
Env Variable | CLI Flag | Description |
---|---|---|
N/A | --uri | This is a shorthand for setting a number of other options all at once in URI form. Components of this URI can overridden by the parameters below. Example: postgres[ql]://[username[:password]@][host[:port],]/database[?parameter_list]. |
ESPRESSO_SEQUENCER_POSTGRES_HOST | --host | Hostname for the remote Postgres database server. |
ESPRESSO_SEQUENCER_POSTGRES_PORT | --port | Port for the remote Postgres database server. |
ESPRESSO_SEQUENCER_POSTGRES_DATABASE | --database | Name of database to connect to. |
ESPRESSO_SEQUENCER_POSTGRES_USER | --user | Postgres user to connect as. |
ESPRESSO_SEQUENCER_POSTGRES_PASSWORD | --password | Password for Postgres user. |
ESPRESSO_SEQUENCER_POSTGRES_USE_TLS | --use-tls | Use TLS for an encrypted connection to the database. |
ESPRESSO_SEQUENCER_POSTGRES_PRUNE | --prune | Use this flag or set variable to |
ESPRESSO_SEQUENCER_PRUNER_PRUNING_THRESHOLD | --pruning-threshold | If storage usage exceeds this threshold (in bytes), data younger than the target retention will be pruned (possibly up to the minimum retention) |
ESPRESSO_SEQUENCER_PRUNER_MINIMUM_RETENTION | --minimum-retention | The minimum time which data must be retained, regardless of storage usage |
ESPRESSO_SEQUENCER_PRUNER_TARGET_RETENTION | --target-retention | The desired amount of time to retain data, storage permitting |
ESPRESSO_SEQUENCER_PRUNER_BATCH_SIZE | --batch-size | The number of objects to delete at once when pruning |
ESPRESSO_SEQUENCER_PRUNER_MAX_USAGE | --max-usage | The maximum fraction of pruning-threshold to use. If storage usage exceeds pruning-threshold, it will be pruned back to this fraction of pruning-threshold. Expressed as an integer on a scale of 1 to 10000. |
ESPRESSO_SEQUENCER_PRUNER_INTERVAL | --internval | Interval for running the pruner. |
ESPRESSO_SEQUENCER_FETCH_RATE_LIMIT | --fetch-rate-limit | Maximum number of simultaneous requests allowed when fetching missing data from peers. Setting this can limit the load placed on peers by catchup and in turn make catchup more efficient. E.g. 25. |
ESPRESSO_SEQUENCER_ACTIVE_FETCH_DELAY | --active-fetch-delay | The minimum delay between requests to fetch data from another node, when syncing a DA or archival node. This can be used to ensure this node complies with the upstream node's rate limit. E.g. 50ms. |
ESPRESSO_SEQUENCER_CHUNK_FETCH_DELAY | --chunk-fetch-delay | The minimum delay between loading chunks of data in a sequential stream. This can limit the load a node places on its own database, especially for streaming from old blocks, where lots of data is loaded from the database eagerly. E.g. 100ms. |
Submit
This module extends the HTTP API with a POST endpoint to submit a transaction for sequencing.
Usage:
Key Management
Each sequencer node needs two signing key pairs to run:
The staking key is a BLS key used to sign consensus messages (votes, proposals), and it supports efficient signature aggregation, important for consensus performance.
The state key is a Schnorr key used to sign finalized consensus states, which in turn drives the onchain Espresso light client on L1.
These keys are typically stored in a .env
file within the sequencer container, and the sequencer is configured via ESPRESSO_SEQUENCER_KEY_FILE
to load private keys from this file. While you are welcome to generate these keys however you like, as long as they have the right performance, Espresso provides a utility program keygen
which is distributed with the sequencer
image. The simplest way to generate keys is:
Here $CONTAINER
is the ID of the Docker container in which you will be running the sequencer
node (built from the ghcr.io/espressosystems/espresso-sequencer/sequencer:main
image). This command will generate a file called /keys/0.env
in the Docker container containing the private keys. It will also print the generated public keys in the terminal. You can then pass this file to the sequencer by setting ESPRESSO_SEQUENCER_KEY_FILE=/keys/0.env
.
This method of generating keys is nice because the keys never leave the Docker container where they will be used. If, however, you want to store the keys on the host machine as well, or if you want to use a different container to generate the keys than you will use to run the sequencer (such as a one-off container from docker run
) you need only create a Docker volume to store the keys in a host directory, such as
This will store the generated keys at ./keys
on the host. You can then pass them into the sequencer by mounting the same volume in the sequencer container.
The keygen
utility has some additional options which you can view by running with --help
. One of the most useful is --seed <SEED>
, to use a seed for generating the keys deterministically, instead of using entropy from the OS. This is particularly useful if you want to use your own entropy instead of the default entropy source: you can generate a randomized seed however you like and then pass it to the keygen
program. The seed is a 32-byte integer encoded as hex (with no 0x
prefix).
Monitoring
When running the status API, the performance of a sequencer node can be monitored using Prometheus tools, by monitoring the endpoint /status/metrics
. Some of the most important metrics to monitor include:
consensus_current_view
: should be incrementing once every 1-2 seconds. In rare cases it is acceptable for this metric to remain static for up to 1 minute. If not increasing, it may mean the network has lost liveness, or your node has fallen out of sync with the network.consensus_last_decided_view
: should be increasing mostly in tandem withconsensus_current_view
. Ifcurrent_view
is increasing butlast_decided_view
is not, it indicates a network-wide problem with consensus state, or a recurring problem with builders or proposers.consensus_outstanding_transactions
: smaller is better, and this metric should not show any trend over time. If it is especially large (relative to volume) or increasing over a long period of time, it may indicate that your node is not garbage collecting the public mempool properly.
Modes
It is possible to run an Espresso node in three modes, differentiated by how long the nodes store historical data.
Lightweight Node
A lightweight node stores only the data needed to run consensus. It does not keep any historical data, and it is not eligible to be on the consensus DA committee. It has negligible storage requirements on the order of kilobytes. A lightweight node is any node running without the optional query module.
Archival Node
An archival node stores all historical data in perpetuity, and is thus able to serve queries for arbitrary historical state. It is eligible to be on the DA committee. Its storage requirements depend on how much data the network is processing, which in turn depends on how much the network is being used. In testnets, this has been on the order of tens of gigabytes per month, but in mainnet this may be more.
To run an archival node, simply enable the optional query module without any of the pruning options.
DA Node
Pruning of old data is not yet supported with filesystem storage, and thus it is only possible to run a DA node with Postgres storage at this time.
A DA node provides data availability for recently finalized data. It is eligible to be one the DA committee, because it will make data available for long enough for an archival node to fetch it and persist it, before the data is pruned from the DA node. Unlike the archival node, the DA node has bounded storage requirements.
The storage requirements for a DA node are determined by how long we want it to retain data in the worst case. Typically, we want DA nodes to retain data for 1 week under average load, and a minimum of 1 day under worst case load, which give archival nodes time to ensure the data is persisted long term. Detailed hardware requirements for DA nodes are given below.
To run a DA node, enable the optional query module as you would for an archival node, but additionally set pruning parameters:
ESPRESSO_SEQUENCER_POSTGRES_PRUNE=true
ESPRESSO_SEQUENCER_PRUNER_MINIMUM_RETENTION=1d
ESPRESSO_SEQUENCER_PRUNER_TARGET_RETENTION=7d
ESPRESSO_SEQUENCER_PRUNER_PRUNING_THRESHOLD
set to the worst case storage usage, in bytes, based on the hardware requirementsESPRESSO_SEQUENCER_IS_DA="true"
Hardware Requirements
Hardware requirements are still in flux as we refine our testnets and add new features, but for now we recommend the following:
RAM: 16-32 GB.
CPU: 2-4 Cores.
Storage (DA node): 20 GB minimum, ability to scale to 1 TB on demand.
Storage (non-DA Node): Negligible, kilobytes
Last updated