hardhat.config.js

require("@nomiclabs/hardhat-waffle");
require('dotenv').config();
require("@nomiclabs/hardhat-etherscan");

const chainIds = {
  ganache: 1337,
  goerli: 5,
  hardhat: 31337,
  kovan: 42,
  mainnet: 1,
  rinkeby: 4,
  ropsten: 3,
};

// Ensure that we have all the environment variables we need.
let mnemonic;
if (!process.env.MNEMONIC) {
  throw new Error("Please set your MNEMONIC in a .env file");
} else {
  mnemonic = process.env.MNEMONIC;
}

let infuraApiKey;
if (!process.env.INFURA_API_KEY) {
  throw new Error("Please set your INFURA_API_KEY in a .env file");
} else {
  infuraApiKey = process.env.INFURA_API_KEY;
}

function createNetworkConfig(network) {
  const url = "https://" + network + ".infura.io/v3/" + infuraApiKey;
  return {
    accounts: {
      count: 10,
      initialIndex: 0,
      mnemonic,
      path: "m/44'/60'/0'/0",
    },
    chainId: chainIds[network],
    url,
  };
}

/**
 * @type import('hardhat/config').HardhatUserConfig
 */
module.exports = {
  defaultNetwork: "hardhat",
  networks: {
    hardhat: {
      accounts: {
        mnemonic,
      },
      chainId: chainIds.hardhat,
    },
    mainnet: createNetworkConfig("mainnet"),
    goerli: createNetworkConfig("goerli"),
    kovan: createNetworkConfig("kovan"),
    rinkeby: createNetworkConfig("rinkeby"),
    ropsten: createNetworkConfig("ropsten"),
  },
  paths: {
    artifacts: "./artifacts",
    cache: "./cache",
    sources: "./contracts",
    tests: "./test",
  },
  solidity: {
    compilers: [
      {
        version: "0.6.12",
        settings: {
          // https://hardhat.org/hardhat-network/#solidity-optimizer-support
          optimizer: {
            enabled: true,
            runs: 200,
          },
        },
      }
    ],
  },
  etherscan: {
    apiKey: process.env.ETHERSCAN_API_KEY
  }
};