truffle-config.js

require('babel-register');
require('babel-polyfill');
require('dotenv').config(); //inject environment variables into truffle project

const HDWalletProvider  = require('truffle-hdwallet-provider-privkey');
const PRIVATE_KEY1      = process.env.PRIVATE_KEY1   || '';
const PRIVATE_KEY2      = process.env.PRIVATE_KEY2   || '';
const INFURA_API_KEY    = process.env.INFURA_API_KEY || '';

module.exports = {
  networks: {
    development: {
      networkCheckTimeout: 100000,
      host: "127.0.0.1",
      port: 8545,
      network_id: "*" // Match any network id
    },
    rinkeby: {
      networkCheckTimeout: 100000,
      provider: function() {
        return new HDWalletProvider([PRIVATE_KEY1,PRIVATE_KEY2], `https://rinkeby.infura.io/v3/${INFURA_API_KEY}`);
      },
      network_id: 4,
      gas: 5500000
    },
  },
  contracts_directory: './src/contracts/',
  contracts_build_directory: './src/abis/',
  compilers: {
    solc: {
      optimizer: {
        enabled: true,
        runs: 200
      }
    }
  }
}