snapshot_bootstrapper

Snapshot Bootstrapper Module

The snapshot bootstrapper module downloads and processes a Cardano ledger snapshot to initialize system state before processing the live chain.

Overview

This module:

1. Waits for genesis bootstrap completion
2. Downloads a gzip-compressed NES snapshot and matching UTxO sidecar from configured HTTP URLs
3. Streams and publishes snapshot data (UTXOs, pools, accounts, DReps, proposals)
4. Signals completion to allow chain synchronization to begin

Messages

The snapshot bootstrapper:

• Subscribes to cardano.sequence.bootstrapped - Waits for genesis completion
• Publishes to cardano.snapshot - Streams snapshot data during processing
• Publishes to cardano.sync.command - Signals completion with point to begin sync from

Default Configuration

[global.startup]
network-name = "mainnet"

[module.snapshot-bootstrapper]

# Target epoch to download and process.
epoch = 500

# Data directory
data-dir = "./data"

# Message topics
snapshot-topic = "cardano.snapshot"
bootstrapped-subscribe-topic = "cardano.sequence.bootstrapped"
sync-command-topic = "cardano.sync.command"

# Download settings
[download]
timeout-secs = 300
connect-timeout-secs = 30
progress-log-interval = 200

Directory Structure

The module expects the following files in {data-dir}/{network}/:

• snapshots.json - Snapshot metadata including HTTP download URLs

Each snapshot entry provides:

• url - the NES artifact URL, expected to point to a nes.<slot>.<hash>.cbor.gz object
• utxo_url - an optional explicit UTxO sidecar URL; if omitted, the bootstrapper derives a sibling utxos.<slot>.<hash>.cbor.gz URL in the same directory

CloudFront/S3-hosted artifacts work as normal HTTP downloads. The bootstrapper expects the published objects to be gzip-compressed .cbor.gz files and stores the decompressed results as:

• {data-dir}/{network}/nes.<slot>.<hash>.cbor
• {data-dir}/{network}/utxos.<slot>.<hash>.cbor

Example config.json

{
  "snapshot": 500,
  "points": [
    {
      "epoch": 500,
      "id": "abc123...",
      "slot": 12345678
    }
  ]
}