truffle config

truffle-config.js

require('babel-register');
require('babel-polyfill');
const HDWalletProvider = require("@truffle/hdwallet-provider");

const mnemonic='<your mnemonic>';

module.exports = {
  networks: {
    ropsten: {
      provider: function() {
        return new HDWalletProvider(mnemonic, 'https://ropsten.infura.io/v3/<your infura key>')
      },
      network_id: 3
    },
    development: {
      host: "127.0.0.1",
      port: 7545, //for ganache
      network_id: "*" // Match any network id
    },
  },
  contracts_directory: './src/contracts/',
  contracts_build_directory: './src/abis/',
  compilers: {
    solc: {
      optimizer: {
        enabled: true,
        runs: 200
      }
    }
  }
}