Mithril Snapshot

Bootstrap using a Mithril Snapshot

Mithril is a signature scheme that generates a certificate to convince verifiers that a portion of the stake of a system has signed a message. There’s currently a network of Cardano SPOs continuosuly verifing snapshots of the history of the chain and making them available for consumption by client applications, such as Dolos.

From Dolos’ perspective, the process of bootsrapping with Mihtril involves the following steps (which are executed automatically):

1. Downloading a snapshot from a cloud server
2. Verifying that the Mithril signature is valid
3. Importing block data into Dolos’ internal representation
4. Re-creating the ledger state from the chain history

Configuration

To use Mithril snapshots, Dolos requires a few configuration values to download and verify data:

property	type	example
aggregator	string	”https://aggregator.release-preprod.api.mithril.network/aggregator”
genesis_key	string	”5b3…45d” (redacted)

• aggregator: url of the Mithril aggregator
• genesis_key: hex-encoded value of the Mithril genesis key

This is how the configuration fragment would look like inside a dolos.toml file:

[mithril]
aggregator = "https://aggregator.release-preprod.api.mithril.network/aggregator"
genesis_key = "5b3132372c37332c3132342c3136312c362c3133372c3133312c3231332c3230372c3131372c3139382c38352c3137362c3139392c3136322c3234312c36382c3132332c3131392c3134352c31332c3233322c3234332c34392c3232392c322c3234392c3230352c3230352c33392c3233352c34345d"

Note

If you use the dolos init command to initialize your configuration, these values will be already populated with their defaults for each of the known networks.

Execution

To execute the Mithril bootstrap procedure, you need to run the following command line:

dolos bootstrap

The process will take from several minutes to a few hours depending on the network. You’ll see a sequence of progress bars describing the each of the steps of the process.

Caution

The process doesn’t support resuming from previous runs, if you interrupt the process you’ll need to start over.

Note

The above command won’t proceed if it detects that you already have data from previous Dolos runs. It will prompt a confirmation dialog to decide if existing data should be deleted.

The bootstrap command has a few optional arguments to help with specific scenarios:

arg	description	default
--download-dir <DOWNLOAD_DIR>	Directory to store the downloaded snapshot	./snapshot
--skip-if-not-empty	Skip the bootstrap if there’s already data in the stores	false
--skip-validation	Skip the Mithril certificate validation	false
--skip-download	Assume the snapshot is already available in the download dir	false
--retain-snapshot	Retain downloaded snapshot instead of deleting it	false