Become an Validator: Building from Source

1. Download and install Lighthouse

If you already have Rust installed, you can install Lighthouse with the following commands:

  • $ git clone
  • $ git checkout ethdenver
  • $ cd lighthouse
  • $ make

You've completed this step when you can run $ lighthouse --help and see the help menu.

2. Start an Eth1 client

As Eth2 relies upon the Eth1 chain for validator on-boarding and eventually Eth1 may use the Eth2 chain as a finality gadget, all Eth2 validators must have a connection to an Eth1 node.

We provide instructions for using Geth (this is, by chance, what we ended up testing with), but you could use any client that implements the JSON RPC via HTTP. At least for Geth, a fast-synced node is sufficient.

Starting Geth

Install geth and then use this command (or equivalent) to start your Eth1 node:

$ geth --goerli --rpc

3. Start your Beacon Node

The beacon node is the core component of Eth2, it connects to other peers over the Internet and maintains a view of the chain.

Start your beacon node with:

$ lighthouse beacon --eth1 --http

Your beacon node has started syncing when you see the following (truncated) log:

Dec 09 12:57:18.026 INFO Syncing                                 est_time: 2 hrs ...

The distance value reports the time since eth2 genesis, whilst the est_time reports an estimate of how long it will take your node to become synced.

It has finished syncing once you see the following (truncated) log:

Dec 09 12:27:06.010 INFO Synced                                  slot: 16835, ...
  • The --http flag enables the HTTP API for the validator client.
  • The --eth1 flag tells the beacon node that it should sync with an Ethereum 1 node (e.g., Geth). This is only required if you wish to run a validator.

4. Generate your validator key

Generate new validator BLS keypairs using:

$ lighthouse account validator new random

Take note of the voting_pubkey of the new validator. This will be the primary identifier of the validator. This is how you can find your validator in block explorers.

You've completed this step when you see the equivalent line:

Dec 02 21:42:01.337 INFO Generated validator directories         count: 1, base_path: "/home/karl/.lighthouse/validators"
  • This will generate a new validator directory in the .lighthouse/validators directory. Your validator directory will be identified by it's public key, which looks something like 0xc483de.... You'll need to find this directory for the next step.
  • These keys are good enough for the Lighthouse testnet, however they shouldn't be considered secure until we've undergone a security audit (planned Jan 2020).

5. Start your validator client

For security reasons, the validator client runs separately to the beacon node. The validator client stores private keys and signs messages generated by the beacon node.

You'll need both your beacon node and validator client running if you want to stake.

Start the validator client with:

$ lighthouse validator

The validator client is running and has found your validator keys from step 3 when you see the following log:

Dec 09 13:08:59.171 INFO Loaded validator keypair store          voting_validators: 1
Dec 09 13:09:09.000 INFO Awaiting activation                     slot: 17787, ...

If your beacon node hasn't finished syncing yet, you'll see some ERRO messages indicating that your node isn't synced yet. It is safest to wait for your node to sync before moving onto the next step, otherwise your validator may activate before you're able to produce blocks and attestations. However, it generally takes 4-8+ hours after deposit for a validator to become active. If your est_time is less than 4 hours, you should be fine to just move to the next step. After all, this is a testnet and you're only risking Goerli ETH.

Installation complete!

In the next step you'll need to locate your eth1_deposit_data.rlp file from your .lighthouse/validators directory.

The ./lighthouse directory is in your $HOME directory. For example, if you're in Linux and your user is karlm, you can find your validator directory in /home/karlm/.lighthouse/validators/.

You can now go to Become a Validator: Step 2.