truffle-config.js

/**
 * Use this file to configure your truffle project. It's seeded with some
 * common settings for different networks and features like migrations,
 * compilation and testing. Uncomment the ones you need or modify
 * them to suit your project as necessary.
 *
 * More information about configuration can be found at:
 *
 * truffleframework.com/docs/advanced/configuration
 *
 * To deploy via Infura you'll need a wallet provider (like truffle-hdwallet-provider)
 * to sign your transactions before they're sent to a remote public node. Infura accounts
 * are available for free at: infura.io/register.
 *
 * You'll also need a mnemonic - the twelve word phrase the wallet uses to generate
 * public/private key pairs. If you're publishing your code to GitHub make sure you load this
 * phrase from a file you've .gitignored so it doesn't accidentally become public.
 *
 */

const HDWalletProvider = require('truffle-hdwallet-provider');
// const infuraKey = "fj4jll3k.....";
//
// const fs = require('fs');
// const mnemonic = fs.readFileSync(".secret").toString().trim();

const path = require("path");

const mnemonic = process.env.MNEMONIC;

module.exports = {
  contracts_build_directory: path.join(__dirname, "client/src/contracts"),
  networks: {
    ropsten: {
      provider: function() {
        return new HDWalletProvider(mnemonic, "https://ropsten.infura.io/v3/b81c00acfa254c5dbefa77dd3a3b588e")
      },
      network_id: 3
    }   
  }
};