Hardhat

In this tutorial, we'll walk through creating a basic Hardhat project and deploying a token contract.

Here's a video walkthrough:

Prerequisites

Before you begin, ensure you've:

1. Set up your wallet
2. Funded your wallet with Linea ETH
3. Set up your environment using Hardhat's recommended instructions.

Create a Hardhat project

To create an empty Hardhat project, run the following commands:

mkdir linea-tutorial

cd linea-tutorial

npm init

npm install --save-dev hardhat

npx hardhat

In the menu that appears, select Create an empty hardhat.config.js and press Enter.

Hardhat recommends using their plugin, @nomicfoundation/hardhat-toolbox, which can be downloaded by entering Y during the project creation process or by running:

npm install --save-dev @nomicfoundation/hardhat-toolbox @nomicfoundation/hardhat-network-helpers @nomicfoundation/hardhat-chai-matchers @nomiclabs/hardhat-ethers @nomiclabs/hardhat-etherscan chai ethers hardhat-gas-reporter solidity-coverage @typechain/hardhat typechain @typechain/ethers-v5 @ethersproject/abi @ethersproject/providers

And adding the line require("@nomicfoundation/hardhat-toolbox"); to the top of hardhat.config.js file.

Write the smart contract

To write a smart contract, replace the file Lock.sol with Token.sol. Add the following code:

pragma solidity 0.8.18;

// SPDX-License-Identifier: MIT

contract Token {
  string public name = "My Token";
  string public symbol = "MTK";
  uint8 public decimals = 18;
  uint256 public totalSupply = 100000000;

  mapping (address => uint256) public balances;
  address public owner;

  constructor() {
    owner = msg.sender;
    balances[owner] = totalSupply;
  }

  function transfer(address recipient, uint256 amount) public {
    require(balances[msg.sender] >= amount, "Insufficient balance.");
    balances[msg.sender] -= amount;
    balances[recipient] += amount;
  }
}

Then, to compile your contract, run npx hardhat compile.

Create a deployment script

To deploy your contract, we'll need to write a deployment script for Token.sol. Replace the code in scripts/deploy.js with:

async function main() {
  const [deployer] = await ethers.getSigners();

  console.log("Deploying contracts with the account:", deployer.address);

  console.log("Account balance:", (await deployer.getBalance()).toString());

  const Token = await ethers.getContractFactory("Token");
  const token = await Token.deploy();

  console.log("Token address:", token.address);
}

main()
  .then(() => process.exit(0))
  .catch((error) => {
    console.error(error);
    process.exit(1);
  });

Deploy your contract

You can deploy with Hardhat by adding Linea to your hardhat.config.js, but you can also use Truffle Dashboard to deploy directly with your MetaMask wallet.

Truffle Dashboard

Truffle Dashboard allows you to forgo saving your private keys locally, instead connecting to your MetaMask wallet for deployments. To deploy with Truffle Dashboard:

1. Install Truffle using the recommended installation procedure

2. Run truffle dashboard in your terminal, which will open a window on port 24012.

3. Navigate to localhost:24012 in your browser. Please ensure that Dashboard is connected to the Linea testnet by connecting your MetaMask wallet to Linea. For reference, the Linea testnet network ID is 59140.

   

4. Add the Dashboard network to your hardhat.config.js

   networks: {
     // other networks
     truffledashboard: {
       url: "http://localhost:24012/rpc"
     }
   },

5. In a separate terminal, in your Hardhat project, run

   npx hardhat run scripts/deploy.js --network truffledashboard

6. Navigate back to localhost:24012. You should see a prompt asking you to confirm the deployment. Click Confirm.

   

7. You should see something similar to:

   Deploying contracts with the account: YOUR_ACCOUNT_NUMBER
   Account balance: 71790921294697313
   Token address: 0xD8b30F2B76361AD82d086414a1c47b0062DCBaf3

hardhat.config.js

To deploy to Linea, we'll need to add the network to our hardhat.config.js. To do this:

1. Create a .env file in the root folder with your wallet's private key.

   PRIVATE_KEY=YOUR_PRIVATE_KEY_HERE
   danger

   Please do not check your keys into source control. We recommend adding .env to your .gitignore

2. Download dotenv

   npm i -D dotenv

3. Add Linea to your hardhat.config.js file. We highly recommend using the Infura endpoint, as the public endpoint may experience rate limiting. You can find how to get an API key here.

   Using Infura:

   require("@nomicfoundation/hardhat-toolbox");
   require("dotenv").config();
   const { PRIVATE_KEY } = process.env;
   
   module.exports = {
     solidity: "0.8.17",
     networks: {
       linea: {
         url: `https://linea-goerli.infura.io/v3/YOUR-INFURA-API-KEY`,
         accounts: [PRIVATE_KEY],
       },
     },
   };

   Using the public endpoint:

   require("@nomicfoundation/hardhat-toolbox");
   require("dotenv").config();
   const { PRIVATE_KEY } = process.env;
   
   module.exports = {
     solidity: "0.8.17",
     networks: {
       linea: {
         url: `https://rpc.goerli.linea.build/`,
         accounts: [PRIVATE_KEY],
       },
     },
   };

4. Call npx hardhat run scripts/deploy.js --network linea from the CLI. Your output should look something like this:

   Deploying contracts with the account: YOUR_ACCOUNT_NUMBER
   Account balance: 71790921294697313
   Token address: 0xD8b30F2B76361AD82d086414a1c47b0062DCBaf3

Next, you can optionally verify your contract on the network.