lighthouse/book/src/interop-scenarios.md

Interop Scenarios

Here we demonstrate some expected interop scenarios.

All scenarios assume a working development environment and commands are based in the target/release directory (this is the build dir for cargo).

Additional functions can be found in the interop cheat-sheet.

Table of contents

• Starting from avalidator_count, genesis_time tuple
• Starting a node from a genesis state file
• Starting a validator client
• Exporting a genesis state file from a running Lighthouse node

Start beacon node given a validator count and genesis_time

To start a brand-new beacon node (with no history) use:

$ ./beacon_node testnet -f quick 8 <GENESIS_TIME>

Where GENESIS_TIME is in unix time.

Notes:

• This method conforms the "Quick-start genesis" method in the ethereum/eth2.0-pm repository.
• The -f flag ignores any existing database or configuration, backing them up before re-initializing.
• 8 is the validator count and 1567222226 is the genesis time.
• See $ ./beacon_node testnet quick --help for more configuration options.

Start Beacon Node given a genesis state file

A genesis state can be read from file using the testnet file subcommand. There are three supported formats:

• ssz (default)
• json
• yaml

Start a new node using /tmp/genesis.ssz as the genesis state:

$ ./beacon_node testnet --spec minimal -f file ssz /tmp/genesis.ssz

Notes:

• The -f flag ignores any existing database or configuration, backing them up before re-initializing.
• See $ ./beacon_node testnet file --help for more configuration options.
• The --spec flag is required to allow SSZ parsing of fixed-length lists.

Start an auto-configured validator client

To start a brand-new validator client (with no history) use:

$ ./validator_client testnet -b insecure 0 8

Notes:

• The -b flag means the validator client will "bootstrap" specs and config from the beacon node.
• The insecure command dictates that the interop keypairs will be used.
• The 0 8 indicates that this validator client should manage 8 validators, starting at validator 0 (the first deposited validator).
• The validator client will try to connect to the beacon node at localhost. See --help to configure that address and other features.
• The validator client will operate very unsafely in testnet mode, happily swapping between chains and creating double-votes.

Exporting a genesis file

Genesis states can downloaded from a running Lighthouse node via the HTTP API. Three content-types are supported:

• application/json
• application/yaml
• application/ssz

Using curl, a genesis state can be downloaded to /tmp/genesis.ssz:

$ curl --header "Content-Type: application/ssz" "localhost:5052/beacon/state/genesis" -o /tmp/genesis.ssz