> For the complete documentation index, see [llms.txt](https://docs.re.al/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.re.al/build-on-re.al/smart-contracts/deploy-using-hardhat.md).

# 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](https://hardhat.org/getting-started/).

## 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 project
* **Press** `<ENTER>` to set the project root
* **Press** `<ENTER>` again to accept addition of `.gitignore`
* **Press** `<ENTER>` to install `hardhat @nomicfoundation/hardhat-toolbox`

## Create deployer account

* Create the `.env` file in your project root folder and add the following line:

```bash
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.

<details>

<summary>How to get your Private Key in Metamask</summary>

* Click the vertical 3 dots in the upper-right corner of Metamask window
* Select **Account details** and then click **Show private key**
* Enter your Metamask password to reveal the private key
* Copy the private key and paste it into the `.env` file.

</details>

{% hint style="danger" %}
**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.
{% endhint %}

## Configure Hardhat

* Open the `hardhat.config.js` file and paste the code below:

```js
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],
    },
  },
};
```

```js
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

{% hint style="info" %}
The existing smart contract code that comes with the sample project is a `Lock.sol` contract. Feel free to delete it or leave it.
{% endhint %}

* Create a new file, in the contracts folder, named `Counter.sol`:

```bash
touch contracts/Counter.sol
```

* Copy the below code and paste it in the `Counter.sol` contract code:

```solidity
//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:

```js
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),

  ```bash
  npx hardhat compile
  ```

## Deploy Contract

* Run the deploy script:

  ```bash
  npx hardhat run scripts/deploy.js --network unreal
  ```

  ​Here's an output example:

  ```bash
  Counter contract deployed to https://unreal.explorer.startale.com/address/0x8731DC57f9C7e01f5Ba733E7a10692cA540862f8
  ```


---

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