Deploy Using Hardhat
Hardhat is a popular smart contract development frameworks. In this tutorial, we will be using Hardhat to deploy a simple Counter smart contract to the Custom Rollup Testnet. We will explore the basics of creating a Hardhat project with a sample contract and a script to deploy it.
For the full instruction on how to use Hardhat, please refer to the official Hardhat documentation.
Create New Project
Start with creating an npm project by going to an empty folder, running npm init
, and following its instructions. You can use another package manager, like yarn, but Hardhat recommends you use npm 7 or later, as it makes installing Hardhat plugins simpler.
Hardhat Smart Contract
To create the sample project, run npx hardhat init
in your project folder:
Press
<ENTER>
choose javascript, typescript or empty projectPress
<ENTER>
to set the project rootPress
<ENTER>
again to accept addition of.gitignore
Press
<ENTER>
to installhardhat @nomicfoundation/hardhat-toolbox
Create deployer account
Create the
.env
file in your project root folder and add the following line:
ACCOUNT_PRIVATE_KEY='my private key'
Populate the
.env
file with your private key. You can get your private key from Metamask. See the section below on how to get your private key from Metamask.
Do not commit your private key to a public repository!
Verify that your .gitignore file contains .env
to prevent your private key from being committed to a public repository.
Configure Hardhat
Open the
hardhat.config.js
file and paste the code below:
require("dotenv").config();
require("@nomicfoundation/hardhat-toolbox");
module.exports = {
solidity: "0.8.19",
paths: {
artifacts: "./src",
},
networks: {
unreal: {
url: `https://rpc.unreal.gelato.digital`,
accounts: [process.env.ACCOUNT_PRIVATE_KEY],
},
},
};
import { HardhatUserConfig } from "hardhat/config";
import "@nomicfoundation/hardhat-toolbox";
import * as dotenv from "dotenv";
dotenv.config({ path: __dirname + "/.env" });
const ACCOUNT_PRIVATE_KEY = process.env.ACCOUNT_PRIVATE_KEY || "";
console.log("PrivateKey set:", !!ACCOUNT_PRIVATE_KEY);
const config: HardhatUserConfig = {
solidity: "0.8.19",
paths: {
artifacts: "./src",
},
networks: {
unreal: {
url: `https://rpc.unreal.gelato.digital`,
accounts: [ACCOUNT_PRIVATE_KEY],
},
},
};
export default config;
Write Smart Contract
Create a new file, in the contracts folder, named
Counter.sol
:
touch contracts/Counter.sol
Copy the below code and paste it in the
Counter.sol
contract code:
//SPDX-License-Identifier: MIT
pragma solidity ^0.8.19;
contract Counter {
uint256 currentCount = 0;
function increment() public {
currentCount = currentCount + 1;
}
function retrieve() public view returns (uint256){
return currentCount;
}
}
Create Deploy Script
Delete the content of the
scripts/deploy.js
file and add the code below:
const hre = require("hardhat");
async function main() {
const deployedContract = await hre.ethers.deployContract("Counter");
await deployedContract.waitForDeployment();
console.log(
`Counter contract deployed to https://unreal.explorer.startale.com/address/${deployedContract.target}`
);
}
main().catch((error) => {
console.error(error);
process.exitCode = 1;
});
Compile Contract
Install dotenv package:
npm install dotenv
Compile your contract code (i.e., go back to the project root in the CLI),
npx hardhat compile
Deploy Contract
Run the deploy script:
npx hardhat run scripts/deploy.js --network unreal
Here's an output example:
Counter contract deployed to https://unreal.explorer.startale.com/address/0x8731DC57f9C7e01f5Ba733E7a10692cA540862f8