Running a Builder

Information about running a builder for the Espresso Network

Overview

Participants creating blocks for the Espresso Network must run a builder, a piece of software which tracks the state of HotShot consensus so that it is able to and propose blocks at the correct time. The builder functions to create a block filled with transactions, drawing from transactions accessible in Espresso's public mempool as well as its own private mempool.

Espresso provides a simple builder implementation, which participants can run out-of-the-box or build their own software on top of. This document describes how to run the basic builder software.

For comprehensive guidance on the design of an Espresso builder, it is recommended to refer to the hotshot-builder-core repository. Furthermore, to gain insight into the process of enabling builder services for a sequencer, pertinent information can be found at espresso-sequencer-builder. For access to the most recent builder Docker images, please visit here.

Usage

# Clone the espresso-sequencer repository
git clone https://github.com/EspressoSystems/espresso-sequencer

# Build the executable in release mode
cargo build --release

# Run a builder natively
target/release/permissionless-builder [options]

# To understand more about the available builder options
target/release/permissionless-builder -h

# Run a node with the builder docker image
docker run -it \
  [-e ENV=VALUE...] \
  ghcr.io/espressosystems/espresso-sequencer/builder:main

For a quick start, we recommend referring to the espresso-sequencer docker-compose file, and looking particularly at permissionless-builder.

Parameters & options

Environment variable	CLI flag	Description
ESPRESSO_SEQUENCER_HOTSHOT_EVENT_STREAMING_API_URL	--hotshot-event-streaming-url	URL of hotshot events API running on Espresso Sequencer DA committee node. A builder will subscribe to this server to receive hotshot events. (e.g. http://localhost:8081)
ESPRESSO_BUILDER_ETH_MNEMONIC	--eth-mnemonic	Mnemonic phrase for builder account (e.g. "test test test test test test test test test test test junk")
ESPRESSO_BUILDER_ETH_ACCOUNT_INDEX	--eth-account-index	Index of a funded account. Note: This account must be funded in Espresso, meaning ETH must be bridged from the L1
ESPRESSO_BUILDER_L1_PROVIDER	--l1-provider-url	A Url builder will use for RPC communication with L1 (e.g. http://demo-l1-network:8545)
ESPRESSO_SEQUENCER_STATE_PEERS	--state-peers	Peer nodes use to fetch missing state
ESPRESSO_SEQUENCER_CHAIN_ID	--chain-id	Unique identifier for an instance of the sequencer network
ESPRESSO_SEQUENCER_MAX_BLOCK_SIZE	--max-block-size	Maximum allowed size (in bytes) for a block
ESPRESSO_SEQUENCER_BASE_FEE	--base-fee	Minimum fee in WEI per byte of payload
ESPRESSO_BUILDER_SERVER_PORT	--port	Port to run builder server on through which sequencer node can query builder provided APIs (e.g 41003)
ESPRESSO_BUILDER_BOOTSTRAPPED_VIEW	--view-number	Bootstrapping View number (e.g. 0)
ESPRESSO_BUILDER_CHANNEL_CAPACITY	--channel-capacity	The most outstanding hotshot events a builder wants at a point in time (e.g. 1024)
ESPRESSO_BUILDER_WEBSERVER_RESPONSE_TIMEOUT_DURATION	--max-api-timeout-duratio	The amount of time a builder can wait before timing out a request to the API (e.g 1s)
ESPRESSO_BUILDER_BUFFER_VIEW_NUM_COUNT	--buffer-view-num-count	The number of views to buffer before a builder garbage collects its state (e.g. 15)

Hardware requirements

Hardware requirements are subject to change as new features are added, but for now we recommend the following:

• Memory: 4-8 GB

• CPU: 2-4 Cores