Deploying Eth Smart Contracts with Truffle

https://remix.ethereum.org/ with injected Web3 using Metamask is the simplest way to deploy smart contracts onto Eth-type blockchains. It requires no setup, aside from a Metamask installation. However, sometimes it just isn’t practical to use Remix.

Using Truffle to deploy smart contracts is another good option. Truffle allows you to deploy contracts via your local system directly to any network you choose.

Create a New Repo and Install Truffle

mkdir myproject
cd myproject
npm install truffle
npm install @truffle/hdwallet-provider
truffle init

This will initialize a new truffle project in the myproject folder. It will also install a wallet provider, which will allow you to make use of your existing eth wallet by providing the secret mnemonic phrase.

Create a New Solidity File

Add the following code to the contracts folder of your project in a file named ShowOwner.sol:

pragma solidity >=0.8.1;

contract ShowOwner{
  
  address private owner;

  constructor(){
      owner = msg.sender;
  }

  function getOwner() public view returns(address){
      return owner;
  }
}

Upon creation the contract records the address of the contract creator (your wallet address). Calling the getOwner() function will return the address of the contract creator.

Contract Deployment

Enter the migrations folder and create this file: 2_deploy_contracts.js

The contents of 2_deploy_contracts.js should be:

var ShowOwner = artifacts.require("ShowOwner");

module.exports = function(deployer) {
    deployer.deploy(ShowOwner);
    // Additional contracts can be deployed here
};

This code simply tells truffle to register the ShowOwner contract and to deploy.

Get Rid of Extraneous Migrations

Truffle has a feature which automatically registers new migrations to the blockchain. This means that every time you deploy a contract in a Truffle project, the record of that change is saved as a SECOND migration contract on chain. Some may find this useful, but for most this just serves as an unnecessary extra expense. After all, every time we deploy a contract to an eth blockchain it costs money in the form of gas.

You can disable this by changing the 1_initial_migration.js file in the migrations folder to:

const Migrations = artifacts.require("Migrations");

module.exports = function (deployer) {
  if(deployer.network_id != 97){
         deployer.deploy(Migrations);
  }
};

This makes it so that migration recording will not take place if the network id is 97. We’ll talk about network ids in the next section.

Configure the Network

We’ll be deploying our contract to the Binance Smart Chain Testnet. In the root folder of your project, update truffle-config.js to:

var HDWalletProvider = require("truffle-hdwallet-provider");
const MNEMONIC = 'YOUR_MNEMONIC';


module.exports = {
  networks: {
    bsctestnet: {
      provider: function() {
        return new HDWalletProvider(MNEMONIC, "https://data-seed-prebsc-2-s3.binance.org:8545")
      },
      network_id: 97,
      gas: 4000000
    }
  },

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

  // Configure your compilers
  compilers: {
    solc: {
      version: "0.8.1"
    }
  },

  db: {
    enabled: false
  }
};

Make sure to replace ‘YOUR_MNEMONIC’ with the 12 word mnemonic from your wallet. If you are using git for version control, make sure you add truffle-config.js to your .gitignore file, otherwise you may end up sharing your private mnemonic with the world! You WILL lose all of the cypto in your wallet if you do that.

Note: Metamask allows you to create multiple accounts for a single wallet mnemonic. Truffle will make use of Account 1 by default.

Here we’ve created a network called bsctestnet. The BSC testnet node is at https://data-seed-prebsc-2-s3.binance.org:8545. Remember the network id we’d mentioned in our migration omission script earlier? It shows up here. The network is is 97.

You might have noticed the compilers section. This allows you to set your desired solc compiler version. The default is version 0.5.4. In our case, compiler version 0.5.4 won’t work because our contract is set to use version 0.8.1 or higher.