Using Hardhat to Deploy To Moonbeam¶

Introduction¶

Hardhat is a flexible and extensible Ethereum development environment that streamlines the smart contract development process. Since Moonbeam is Ethereum-compatible, you can use Hardhat to develop and deploy smart contracts on Moonbeam.

Hardhat takes a task-based approach to development, where you can define and execute tasks that perform specific actions. These actions include compiling and deploying contracts, running tests, and more. Tasks are highly configurable, so you can create, customize, and execute tasks that are tailored to meet your needs.

You can also extend Hardhat's functionality through the use of plugins. Plugins are external extensions that integrate with Hardhat to provide additional features and tools for your workflow. For example, there are plugins for common Ethereum libraries, like Ethers.js and viem, a plugin that extends the Chai assertion library to include Ethereum-specific functionality, and more. All of these plugins can be used to extend your Hardhat project on Moonbeam.

This guide will provide a brief introduction to Hardhat and show you 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 a Moonbeam development node.

Please note that although Hardhat comes with a Hardhat Network component, which provides a local development environment, you should use a local Moonbeam development node instead. You can connect a Moonbeam development node to Hardhat just like you would with any other network.

Checking Prerequisites¶

To get started, you will need the following:

• Have MetaMask installed and connected to Moonbase Alpha
• Have an account with funds. You can get DEV tokens for testing on Moonbase Alpha once every 24 hours from the Moonbase Alpha Faucet
• 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

Create 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 Hardhat project

   npx hardhat init
   

   Note

   npx is used to run executables installed locally in your project. Although Hardhat can be installed globally, it is recommended to install it 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, which will create a Hardhat configuration file for your project

Hardhat Configuration File¶

The Hardhat configuration file is the entry point into your Hardhat project. It defines various settings and options for your Hardhat project, such as the Solidity compiler version to use and the networks you can deploy your contracts to.

To start, your hardhat.config.js should resemble the following:

/** @type import('hardhat/config').HardhatUserConfig */
module.exports = {
  solidity: '0.8.20',
};

For this example, you can leave the Solidity compiler version to 0.8.20; however, if you are using a different contract that requires a newer version, don't forget to update the version here.

Next, you'll need to modify your configuration file to add the network configurations for the network you want to deploy your contract to. For Moonbeam networks, you'll need to specify the following:

• url - the RPC endpoint of the node
• chainId - the chain ID, which is used to validate the network
• accounts - the accounts that can be used to deploy and interact with contracts. You can either enter an array of the private keys for your accounts or use an HD Wallet

For this example, the network will be Moonbase Alpha, but you can modify the configuration to use any of the Moonbeam networks:

module.exports = {
  solidity: '0.8.20',
  networks: {
    moonbeam: {
      url: 'INSERT_RPC_API_ENDPOINT', // Insert your RPC URL here
      chainId: 1284, // (hex: 0x504),
      accounts: ['INSERT_PRIVATE_KEY'],
    },
  },
};

module.exports = {
  solidity: '0.8.20',
  networks: {
    moonriver: {
      url: 'INSERT_RPC_API_ENDPOINT', // Insert your RPC URL here
      chainId: 1285, // (hex: 0x505),
      accounts: ['INSERT_PRIVATE_KEY'],
    },
  },
};

module.exports = {
  solidity: '0.8.20',
  networks: {
    moonbase: {
      url: 'https://rpc.api.moonbase.moonbeam.network', // Insert your RPC URL here
      chainId: 1287, // (hex: 0x507),
      accounts: ['INSERT_PRIVATE_KEY'],
    },
  },
};

module.exports = {
  solidity: '0.8.20',
  networks: {
    dev: {
      url: 'http://127.0.0.1:9944', // Insert your RPC URL here
      chainId: 1281, // (hex: 0x501),
      accounts: ['INSERT_PRIVATE_KEY'],
    },
  },
};

If you are planning on using any plugins with your project, you'll need to install the plugin and import it into the hardhat.config.js file. Once a plugin has been imported, it becomes part of the Hardhat Runtime Environment, and you can leverage the plugin's functionality within tasks, scripts, and more.

For this example, you can install the hardhat-ethers plugin and import it into the configuration file. This plugin provides a convenient way to use the Ethers.js library to interact with the network.

npm install @nomicfoundation/hardhat-ethers ethers

Additionally, you'll need to install the hardhat-ignition-ethers plugin to enable deployment of smart contracts with Hardhat Ignition. You can install it with the following command:

npm install --save-dev @nomicfoundation/hardhat-ignition-ethers

To import both plugins, add the following require statements to the top of the Hardhat configuration file:

/** @type import('hardhat/config').HardhatUserConfig */
require('@nomicfoundation/hardhat-ethers');
require('@nomicfoundation/hardhat-ignition-ethers');

const privateKey = 'INSERT_PRIVATE_KEY';

module.exports = {
  solidity: '0.8.20',
  networks: {
    moonbase: {
      url: 'https://rpc.api.moonbase.moonbeam.network',
      chainId: 1287, // 0x507 in hex,
      accounts: [privateKey]
    }
  }
};

For more information on the available configuration options, please refer to Hardhat's documentation on Configuration.

The Contract File¶

Now that you've configured your project, you can begin the development process by creating your smart contract. The contract will be a simple one that will let you store a value that can be retrieved later, called Box.

To add the contract, you'll take the following steps:

1. Create a contracts directory

   mkdir contracts
   

2. Create a Box.sol file

   touch contracts/Box.sol
   

3. Open the file and add the following contract to it:

   // contracts/Box.sol
   // SPDX-License-Identifier: MIT
   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;
       }
   }
   

Compile the Contract¶

The next step is to compile the Box.sol smart contract. For this, you can use the built-in compile task, which will look for Solidity files in the contracts directory and compile them using the version and compiler settings defined in the hardhat.config.js file.

To use the compile task, all you have to do is run:

npx hardhat compile

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

If you make changes to the contract after you've compiled it, you can compile it again using the same command. Hardhat will look for any changes and recompile the contract. If no changes are found, nothing will be compiled. If needed, you can force a compilation using the clean task, which will clear the cache and delete the old artifacts.

Deploy the Contract¶

To deploy the contract, you'll use Hardhat Ignition, a declarative framework for deploying smart contracts. Hardhat Ignition is designed to make it easy to manage recurring tasks surrounding smart contract deployment and testing. For more information, be sure to check out the Hardhat Ignition docs.

To set up the proper file structure for your Ignition module, create a folder named ignition and a subdirectory called modules. Then add a new file to it called Box.js. You can take all three of these steps with the following command:

mkdir ignition ignition/modules && touch ignition/modules/Box.js

Next, you can write your Hardhat Ignition module. To get started, take the following steps:

1. Import the buildModule function from the Hardhat Ignition module
2. Export a module using buildModule
3. Use the getAccount method to select the deployer account
4. Deploy the Box contract
5. Return an object from the module. This makes the Box contract accessible for interaction in Hardhat tests and scripts

// 1.  Import the `buildModule` function from the Hardhat Ignition module
const { buildModule } = require("@nomicfoundation/hardhat-ignition/modules");

// 2. Export a module using `buildModule`
module.exports = buildModule("BoxModule", (m) => {

  // 3. Use the `getAccount` method to select the deployer account
  const deployer = m.getAccount(0);

  // 4. Deploy the `Box` contract
  const box = m.contract("Box", [], {
    from: deployer,
  });

  // 5. Return an object from the module 
  return { box };
});

To run the script and deploy the Box.sol contract, use the following command, which requires you to specify the network name as defined in your hardhat.config.js. If you don't specify a network, hardhat will deploy the contract to a local hardhat network by default.

npx hardhat ignition deploy ./ignition/modules/Box.js --network moonbase

You'll be prompted to confirm the network you wish to deploy to. After a few seconds after you confirm, the contract is deployed, and you'll see the contract address in the terminal.

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

Interact with the Contract¶

There are a couple of ways that you can interact with your newly deployed contract using Hardhat: you can use the console task, which spins up an interactive JavaScript console, or you can create another script and use the run task to execute it.

Using the Hardhat Console¶

The Hardhat console uses the same execution environment as the tasks and scripts, so it automatically uses the configurations and plugins defined in the hardhat.config.js.

To launch the Hardhat console, you can run:

npx hardhat console --network moonbase

Next, you can take the following steps, entering 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('0xfBD78CE8C9E1169851119754C4Ea2f70AB159289');
   

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 account configured in the hardhat.config.js file and broadcasted to the network. The output should look similar to:

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();

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

Using a Script¶

Similarly to the deployment script, you can create a script to interact with your deployed contract, store it in the scripts directory, and run it using the built-in run task.

To get started, create a set-value.js file in the scripts directory:

mkdir scripts && touch scripts/set-value.js

Now paste the following contract into the set-value.js file:

// scripts/set-value.js
async function main() {
  // Create instance of the Box contract
  const Box = await ethers.getContractFactory('Box');

  // Connect the instance to the deployed contract
  const box = await Box.attach('0xfBD78CE8C9E1169851119754C4Ea2f70AB159289');

  // Store a new value
  await box.store(2);

  // Retrieve the value
  const value = await box.retrieve();
  console.log(`The new value is: ${value}`);
}

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

To run the script, you can use the following command:

npx hardhat run --network moonbase scripts/set-value.js

The script should return 2 as the value.

Hardhat Forking¶

You can fork any EVM-compatible chain using Hardhat, including Moonbeam. Forking simulates the live Moonbeam network locally, enabling you to interact with deployed contracts on Moonbeam in a local test environment. Since Hardhat forking is based on an EVM implementation, you can interact with the fork using standard Ethereum JSON-RPC methods supported by Moonbeam and Hardhat.

There are some limitations to be aware of when using Hardhat forking. You cannot interact with any of the Moonbeam precompiled contracts or their functions. Precompiles are a part of the Substrate implementation and therefore cannot be replicated in the simulated EVM environment. This prohibits you from interacting with cross-chain assets on Moonbeam and Substrate-based functionality such as staking and governance.

There is currently an issue related to forking Moonbeam, so in order to fix the issue, you'll need to manually patch Hardhat first. You can find out more information by following the issue on GitHub as well as the related PR.

Patching Hardhat¶

Before getting started, you'll need to apply a temporary patch to workaround an RPC error until Hardhat fixes the root issue. The error is as follows:

Error HH604: Error running JSON-RPC server: Invalid JSON-RPC response's result.

Errors: Invalid value null supplied to : RpcBlockWithTransactions | null/transactions: RpcTransaction Array/0: RpcTransaction/accessList: Array<{ address: DATA, storageKeys: Array<DATA> | null }> | undefined, Invalid value null supplied to : RpcBlockWithTransactions | null/transactions: RpcTransaction Array/1: RpcTransaction/accessList: Array<{ address: DATA, storageKeys: Array<DATA> | null }> | undefined, Invalid value null supplied to : RpcBlockWithTransactions | null/transactions: RpcTransaction Array/2: RpcTransaction/accessList: Array<{ address: DATA, storageKeys: Array<DATA> | null }> | undefined

To patch Hardhat, you'll need to open the node_modules/hardhat/internal/hardhat-network/jsonrpc/client.js file of your project. Next, you'll add an addAccessList function and update the _perform and _performBatch functions.

To get started, you can remove the preexisting _perform and _performBatch functions and, in their place, add the following code snippet:

  addAccessList(method, rawResult) {
    if (
      method.startsWith('eth_getBlock') &&
      rawResult &&
      rawResult.transactions?.length
    ) {
      rawResult.transactions.forEach((t) => {
        if (t.accessList == null) t.accessList = [];
      });
    }
  }
  async _perform(method, params, tType, getMaxAffectedBlockNumber) {
    const cacheKey = this._getCacheKey(method, params);
    const cachedResult = this._getFromCache(cacheKey);
    if (cachedResult !== undefined) {
      return cachedResult;
    }
    if (this._forkCachePath !== undefined) {
      const diskCachedResult = await this._getFromDiskCache(
        this._forkCachePath,
        cacheKey,
        tType
      );
      if (diskCachedResult !== undefined) {
        this._storeInCache(cacheKey, diskCachedResult);
        return diskCachedResult;
      }
    }
    const rawResult = await this._send(method, params);
    this.addAccessList(method, rawResult);
    const decodedResult = (0, decodeJsonRpcResponse_1.decodeJsonRpcResponse)(
      rawResult,
      tType
    );
    const blockNumber = getMaxAffectedBlockNumber(decodedResult);
    if (this._canBeCached(blockNumber)) {
      this._storeInCache(cacheKey, decodedResult);
      if (this._forkCachePath !== undefined) {
        await this._storeInDiskCache(this._forkCachePath, cacheKey, rawResult);
      }
    }
    return decodedResult;
  }
  async _performBatch(batch, getMaxAffectedBlockNumber) {
    // Perform Batch caches the entire batch at once.
    // It could implement something more clever, like caching per request
    // but it's only used in one place, and those other requests aren't
    // used anywhere else.
    const cacheKey = this._getBatchCacheKey(batch);
    const cachedResult = this._getFromCache(cacheKey);
    if (cachedResult !== undefined) {
      return cachedResult;
    }
    if (this._forkCachePath !== undefined) {
      const diskCachedResult = await this._getBatchFromDiskCache(
        this._forkCachePath,
        cacheKey,
        batch.map((b) => b.tType)
      );
      if (diskCachedResult !== undefined) {
        this._storeInCache(cacheKey, diskCachedResult);
        return diskCachedResult;
      }
    }
    const rawResults = await this._sendBatch(batch);
    const decodedResults = rawResults.map((result, i) => {
      this.addAccessList(batch[i].method, result);
      return (0, decodeJsonRpcResponse_1.decodeJsonRpcResponse)(
        result,
        batch[i].tType
      );
    });
    const blockNumber = getMaxAffectedBlockNumber(decodedResults);
    if (this._canBeCached(blockNumber)) {
      this._storeInCache(cacheKey, decodedResults);
      if (this._forkCachePath !== undefined) {
        await this._storeInDiskCache(this._forkCachePath, cacheKey, rawResults);
      }
    }
    return decodedResults;
  }

Then you can use patch-package to automatically patch the package by running the following command:

npx patch-package hardhat

A patches directory will be created, and now you should be all set to fork Moonbeam without running into any errors.

Forking Moonbeam¶

You can fork Moonbeam from the command line or configure your Hardhat project to always run the fork from your hardhat.config.js file. To fork 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.

To fork Moonbeam from the command line, you can run the following command from within your Hardhat project directory:

npx hardhat node --fork INSERT_RPC_API_ENDPOINT

npx hardhat node --fork INSERT_RPC_API_ENDPOINT

npx hardhat node --fork https://rpc.api.moonbase.moonbeam.network

If you prefer to configure your Hardhat project, you can update your hardhat.config.js file with the following configurations:

...
networks: {
  hardhat: {
    forking: {
      url: 'INSERT_RPC_API_ENDPOINT',
    },
  },
},
...

...
networks: {
  hardhat: {
    forking: {
      url: 'INSERT_RPC_API_ENDPOINT',
    },
  },
},
...

...
networks: {
  hardhat: {
    forking: {
      url: 'https://rpc.api.moonbase.moonbeam.network',
    },
  },
},
...

When you spin up the Hardhat fork, you'll have 20 development accounts that are pre-funded with 10,000 test tokens. The forked instance is available at http://127.0.0.1:8545/. The output in your terminal should resemble the following:

To verify you have forked the network, you can query the latest block number:

curl --data '{"method":"eth_blockNumber","params":[],"id":1,"jsonrpc":"2.0"}' -H "Content-Type: application/json" -X POST localhost:8545 

If you convert the result from hex to decimal, you should get the latest block number from the time you forked the network. You can cross-reference the block number using a block explorer.

From here, you can deploy new contracts to your forked instance of Moonbeam or interact with contracts already deployed by creating a local instance of the deployed contract.

To interact with an already deployed contract, you can create a new script in the scripts directory using ethers. Because you'll be running it with Hardhat, you don't need to import any libraries. Inside the script, you can access a live contract on the network using the following snippet:

const hre = require('hardhat');

async function main() {
  const provider = new ethers.JsonRpcProvider(
    'http://127.0.0.1:8545/'
  );

  const contract = new ethers.Contract(
    'INSERT_CONTRACT_ADDRESS',
    'INSERT_CONTRACT_ABI',
    provider
  );
}

main().catch((error) => {
  console.error(error);
  process.exitCode = 1;
});