Generate ETH deposit data (based on https://github.com/ChainSafe/lodestar/blob/8a6bc9dbf6d59ff430e70e6df659204bc60f9225/packages/state-transition/test/perf/block/util.ts#L199)

generate_deposit_data.js

import bls from "@chainsafe/bls";
import { deriveKeyFromMnemonic, deriveEth2ValidatorKeys } from "@chainsafe/bls-keygen";
import { fromHexString, toHexString } from "@chainsafe/ssz";
import { computeDomain, computeSigningRoot, ZERO_HASH } from "@lodestar/state-transition";
import { DOMAIN_DEPOSIT } from "@lodestar/params";
import { mainnetChainConfig } from "@lodestar/config/networks";
import { ssz } from "@lodestar/types/phase0";

const masterSK = deriveKeyFromMnemonic("your mnemonic phrase goes here");

const sk = bls.SecretKey.fromBytes(deriveEth2ValidatorKeys(masterSK, 0).signing);

console.log("Pubkey: " + sk.toPublicKey().toHex());

const pubkey = sk.toPublicKey().toBytes();

const eth1Address = "your eth1 address goes here";
const withdrawalCredentials = fromHexString("0x010000000000000000000000" + eth1Address.replace("0x", ""));

const depositMessage = { pubkey, withdrawalCredentials, amount: 32e9 };

const domain = computeDomain(DOMAIN_DEPOSIT, mainnetChainConfig.GENESIS_FORK_VERSION, ZERO_HASH);
const signingRoot = computeSigningRoot(ssz.DepositMessage, depositMessage, domain);
const depositData = { ...depositMessage, signature: sk.sign(signingRoot).toBytes() };
console.log("Deposit data: %o", ssz.DepositData.toJson(depositData));

const depositDataRoot = ssz.DepositData.hashTreeRoot(depositData);
console.log("Deposit data root: " + toHexString(depositDataRoot));