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Using Hardhat to Deploy To Moonbeam

Hardhat Create Project

Introduction

Hardhat is an Ethereum development environment that helps developers manage and automate the recurring tasks inherent to building smart contracts and DApps. Hardhat can directly interact with Moonbeam's Ethereum API so it can also be used to deploy smart contracts into Moonbeam.

This guide will cover how to use Hardhat to compile, deploy, and debug Ethereum smart contracts on the Moonbase Alpha TestNet. This guide can also be adapted for Moonbeam, Moonriver, or Moonbeam development node.

Checking Prerequisites

To get started, you will need the following:

  • Have MetaMask installed and connected to Moonbase Alpha
  • Have an account with funds, which you can get from Mission Control
  • To test out the examples in this guide on Moonbeam or Moonriver, you will need to have your own endpoint and API key which you can get from one of the supported Endpoint Providers.

Creating a Hardhat Project

You will need to create a Hardhat project if you don't already have one. You can create one by completing the following steps:

  1. Create a directory for your project
    mkdir hardhat && cd hardhat
    
  2. Initialize the project which will create a package.json file
    npm init -y
    
  3. Install Hardhat
    npm install hardhat
    
  4. Create a project

    npx hardhat
    

    Note

    npx is used to run executables installed locally in your project. Although Hardhat can be installed globally, we recommend installing locally in each project so that you can control the version on a project by project basis.

  5. A menu will appear which will allow you to create a new project or use a sample project. For this example, you can choose Create an empty hardhat.config.js

Hardhat Create Project

This will create a Hardhat config file (hardhat.config.js) in your project directory.

Once you have your Hardhat project, you can also install the ethers plugin. This provides a convenient way to use the ethers.js library to interact with the network. To install it, run the following command:

npm install @nomiclabs/hardhat-ethers ethers

The Contract File

With your empty project created, next you are going to create a contracts directory. You can do so by running the following command:

mkdir contracts && cd contracts

The smart contract that you'll deploy as an example will be called Box, it will let you store a value that can be retrieved later. In the contracts directory, you can create the Box.sol file:

touch Box.sol

Open the file and add the following contract to it:

// contracts/Box.sol
pragma solidity ^0.8.1;

contract Box {
    uint256 private value;

    // Emitted when the stored value changes
    event ValueChanged(uint256 newValue);

    // Stores a new value in the contract
    function store(uint256 newValue) public {
        value = newValue;
        emit ValueChanged(newValue);
    }

    // Reads the last stored value
    function retrieve() public view returns (uint256) {
        return value;
    }
}

Hardhat Configuration File

Before you can deploy the contract to Moonbase Alpha, you'll need to modify the Hardhat configuration file and create a secure file to store your private key in.

You can create a secrets.json file to store your private key by running:

touch secrets.json

Then add your private key to it:

{
    "privateKey": "YOUR-PRIVATE-KEY-HERE"
}

Make sure to add the file to your project's .gitignore, and to never reveal your private key.

Note

Please always manage your private keys with a designated secret manager or similar service. Never save or commit your private keys inside your repositories.

Next you can take the following steps to modify the hardhat.config.js file and add Moonbase Alpha as a network:

  1. Import the Ethers plugin
  2. Import the secrets.json file
  3. Inside the module.exports, you need to provide the Solidity version (0.8.1 according to our contract file)
  4. Add the Moonbase Alpha network configuration
// 1. Import the ethers plugin required to interact with the contract
require('@nomiclabs/hardhat-ethers');

// 2. Import your private key from your pre-funded Moonbase Alpha testing account
const { privateKey } = require('./secrets.json');

module.exports = {
  // 3. Specify the Solidity version
  solidity: "0.8.1",

  networks: {
    // 4. Add the Moonbase Alpha network specification
    moonbase: {
      url: 'https://rpc.api.moonbase.moonbeam.network',
      chainId: 1287, // 0x507 in hex,
      accounts: [privateKey]
    }
  }
};

You can modify the hardhat.config.js file to use any of the Moonbeam networks:

moonbeam: {
    url: 'RPC-API-ENDPOINT-HERE', // Insert your RPC URL here
    chainId: 1284, // (hex: 0x504),
    accounts: [privateKey]
  },
moonriver: {
    url: 'RPC-API-ENDPOINT-HERE', // Insert your RPC URL here
    chainId: 1285, // (hex: 0x505),
    accounts: [privateKey]
  },
moonbase: {
    url: 'https://rpc.api.moonbase.moonbeam.network',
    chainId: 1287, // (hex: 0x507),
    accounts: [privateKey]
  },
dev: {
    url: 'http://127.0.0.1:9933',
    chainId: 1281, // (hex: 0x501),
    accounts: [privateKey]
  },

Congratulations! You are now ready for deployment!

Compiling Solidity

To compile the contract you can simply run:

npx hardhat compile

Hardhat Contract Compile

After compilation, an artifacts directory is created: it holds the bytecode and metadata of the contract, which are .json files. It’s a good idea to add this directory to your .gitignore.

Deploying the Contract

In order to deploy the Box.sol smart contract, you will need to write a simple deployment script. You can create a new directory for the script and name it scripts and add a new file to it called deploy.js:

mkdir scripts && cd scripts
touch deploy.js

Next, you need to write your deployment script which can be done using ethers. Because you'll be running it with Hardhat, you don't need to import any libraries.

To get started start, take the following steps:

  1. Create a local instance of the contract with the getContractFactory method
  2. Use the deploy method that exists within this instance to instantiate the smart contract
  3. Wait for the deployment by using deployed
  4. Once deployed, you can fetch the address of the contract using the contract instance.
// scripts/deploy.js
async function main() {
   // 1. Get the contract to deploy
   const Box = await ethers.getContractFactory('Box');
   console.log('Deploying Box...');

   // 2. Instantiating a new Box smart contract
   const box = await Box.deploy();

   // 3. Waiting for the deployment to resolve
   await box.deployed();

   // 4. Use the contract instance to get the contract address
   console.log('Box deployed to:', box.address);
}

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

You can now deploy the Box.sol contract using the run command and specifying moonbase as the network:

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

If you're using another Moonbeam network, make sure that you specify the correct network. The network name needs to match how it's defined in the hardhat.config.js.

After a few seconds, the contract is deployed, and you should see the address in the terminal.

Hardhat Contract Deploy

Congratulations, your contract is live! Save the address, as you will use it to interact with this contract instance in the next step.

Interacting with the Contract

To interact with your newly deployed contract on Moonbase Alpha, you can launch the Hardhat console by running:

npx hardhat console --network moonbase

Next you can take the following steps, entering in one line at a time:

  1. Create a local instance of the Box.sol contract
    const Box = await ethers.getContractFactory('Box');
    
  2. Connect the local instance to the deployed contract, using the address of the contract
    const box = await Box.attach('0x425668350bD782D80D457d5F9bc7782A24B8c2ef');
    
  3. Interact with the attached contract. For this example, you can call the store method and store a simple value
    await box.store(5)
    

The transaction will be signed by your Moonbase account and broadcast to the network. The output should look similar to:

Transaction output

Notice your address labeled from, the address of the contract, and the data that is being passed. Now, you can retrieve the value by running:

(await box.retrieve()).toNumber()

You should see 5 or the value you have stored initially.

Congratulations, you have successfully deployed and interacted with a contract using Hardhat!

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