truffle.js

const HDWalletProvider = require("truffle-hdwallet-provider");
const keys = ["ce2eab51c7c428...", "46c36f1970dcf37ec..."];

module.exports = {
    networks: {
        ropsten: {
            provider: () => new HDWalletProvider(keys, "https://ropsten.infura.io/uJhP7KE..."),
            network_id: 3,
            gas: 4500000,
            gasPrice: 40000000000
        }
    },
    network: "ropsten",
    solc: {
        optimizer: {
            enabled: true,
            runs: 200
        }
    }
};