truffle-config.js

const HDWalletProvider = require('@truffle/hdwallet-provider');
require('dotenv').config();


const ALCHEMY_RPC_URL = process.env.ALCHEMY_RPC_URL;
const INFURA_RPC_URL = process.env.INFURA_RPC_URL;
const MNEMONIC = process.env.MNEMONIC;
const ETHERSCAN_API_KEY = process.env.ETHERSCAN_API_KEY;
const ROPSTEN_ALCHEMY_APP_KEY = process.env.ROPSTEN_ALCHEMY_APP_KEY;

module.exports = {

  networks: {
    development: {
      host: "127.0.0.1",     // Localhost (default: none)
      port: 7545,            // Standard Ethereum port (default: none)
      network_id: "*",
      gas: 6721975,
      gasPrice: '20000000000'
      // Any network (default: none)
    },
    // Another network with more advanced options...
    // advanced: {
    // port: 8777,             // Custom port
    // network_id: 1342,       // Custom network
    // gas: 8500000,           // Gas sent with each transaction (default: ~6700000)
    // gasPrice: 20000000000,  // 20 gwei (in wei) (default: 100 gwei)
    // from: <address>,        // Account to send txs from (default: accounts[0])
    // websocket: true        // Enable EventEmitter interface for web3 (default: false)
    // },
    // Useful for deploying to a public network.
    // NB: It's important to wrap the provider as a function.
    ropsten: {
      provider: () => new HDWalletProvider(MNEMONIC, `https://eth-ropsten.alchemyapi.io/v2/${ROPSTEN_ALCHEMY_APP_KEY}`),
    network_id: 3,       // Ropsten's id
    gas: 5500000,        // Ropsten has a lower block limit than mainnet
    confirmations: 2,    // # of confs to wait between deployments. (default: 0)
    timeoutBlocks: 200,  // # of blocks before a deployment times out  (minimum/default: 50)
    skipDryRun: true,     // Skip dry run before migrations? (default: false for public nets )
    networkCheckTimeout: 1000000000
    },

    rinkeby: {
      provider: () => new HDWalletProvider(MNEMONIC, `https://eth-rinkeby.alchemyapi.io/v2/${ALCHEMY_RPC_URL}`),
      network_id: 4,
      gas: 5500000,        // Ropsten has a lower block limit than mainnet
      confirmations: 2,    // # of confs to wait between deployments. (default: 0)
      timeoutBlocks: 200,  // # of blocks before a deployment times out  (minimum/default: 50)
      skipDryRun: true,     // Skip dry run before migrations? (default: false for public nets )
      networkCheckTimeout: 1000000000
    },
  },
    // Useful for private networks
    // private: {
    // provider: () => new HDWalletProvider(mnemonic, `https://network.io`),
    // network_id: 2111,   // This network is yours, in the cloud.
    // production: true    // Treats this network as if it was a public net. (default: false)
    // }

  // Set default mocha options here, use special reporters etc.
  mocha: {
    timeout: 100000
  },

  // Configure your compilers
  compilers: {
    solc: {
      version: "^0.8.0",    // Fetch exact version from solc-bin (default: truffle's version)
      // docker: true,        // Use "0.5.1" you've installed locally with docker (default: false)
       settings: {          // See the solidity docs for advice about optimization and evmVersion
       optimizer: {
         enabled: true,
         runs: 200
       },
      //  evmVersion: "byzantium"
      // }
    }
  },
  },
  // Truffle DB is currently disabled by default; to enable it, change enabled: false to enabled: true
  //
  // Note: if you migrated your contracts prior to enabling this field in your Truffle project and want
  // those previously migrated contracts available in the .db directory, you will need to run the following:
  // $ truffle migrate --reset --compile-all
  plugins: [
    'truffle-plugin-verify'
  ],

  api_keys: {
    etherscan: ETHERSCAN_API_KEY
  },

  db: {
    enabled: false
  }
};