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Bootstrap Snapshots

Amaru bootstrap expects a window of three consecutive epoch snapshots. The runtime discovers that window from <network>/index.json in the configured S3-compatible bucket. See Publishing bootstrap snapshots to publish a generated snapshot set.

Create a Snapshot Set

Prerequisites

  • db-analyser on $PATH — known working version: 11.0.1 (ships with cardano-node releases)
  • Internet access for Koios (epoch/block metadata) and Mithril (cardano-db download)

Running the command

Generate a bootstrap set by passing the target starting epoch for Amaru to amaru snapshot create. For example, to start in epoch 166:

cargo run --bin amaru -- snapshot create --network preprod --epoch 166

This creates the snapshots for epochs 163, 164, and 165 on preprod:

The command is fully resumable: Mithril downloads are skipped when the local cardano-db already covers all target slots, and db-analyser work is reused when a matching snapshot directory already exists on disk.

Steps performed for each target epoch

  1. Fetch block metadata — queries Koios for the last block of the epoch (slot, hash, parent point).
  2. Download or resume cardano-db — synchronises immutable files from Mithril up to the required slot; skipped entirely when local data already covers all target slots.
  3. Run db-analyser — invokes db-analyser --store-ledger <slot> to produce a raw ledger state snapshot.
  4. Materialize snapshot — assembles the snapshot directory at snapshots/<network>/<slot>.<hash>/ (see Snapshot format below).
  5. Archive — compresses the directory into snapshots/<network>/<slot>.<hash>.tar.zst.

Snapshot format

Each materialized snapshot directory contains:

<slot>.<hash>/
├── bootstrap.headers.json   # JSON array of exactly two hex-encoded CBOR block headers
│                            # that immediately follow the snapshot point. Extracted
│                            # directly from the Mithril immutable .chunk files.
├── meta                     # Metadata directory produced by db-analyser
├── state                    # Ledger state directory produced by db-analyser
├── tables/
│   └── tvar                 # Binary ledger-state tables file produced by db-analyser
│                            # (db-analyser writes this as a flat 'tables' file;
│                            # amaru snapshot create relocates it to tables/tvar on materialization)