Getting started

Hardhat is an Ethereum development environment, designed for easy smart contract development in Solidity. One of its most prominent features is extendability: you can easily add new plugins to your hardhat project.

zkSync supports two plugins for hardhat:

@matterlabs/hardhat-zksync-solc for smart contract compilation.
@matterlabs/hardhat-zksync-deploy for smart contract deployment.

To learn more about hardhat itself, check out their documentation.

This tutorial shows how to set up a zkSync hardhat project from scratch.

Prerequisites

For this tutorial, the following programs must be installed:

yarn package manager. npm examples will be added soon.
Docker for compilation.
A wallet with some Görli ETH on L1 (Görli USDC is also required for the ERC-20 tutorial) to pay for bridging funds to zkSync as well as deploying smart contracts.

Initializing the project

Initialize the project and install the dependencies. Run the following commands in the terminal:

mkdir greeter-example
cd greeter-example
yarn init -y
yarn add -D typescript ts-node ethers zksync-web3 hardhat @matterlabs/[email protected] @matterlabs/[email protected]

typescript and ts-node are optional - plugins will work fine in vanilla JavaScript environment. Although, please note that this tutorial does use TypeScript.

Create the hardhat.config.ts file and paste the following code within it:

require("@matterlabs/hardhat-zksync-deploy");require("@matterlabs/hardhat-zksync-solc");module.exports = {  zksolc: {    version: "0.1.0",    compilerSource: "docker",    settings: {      optimizer: {        enabled: true,      },      experimental: {        dockerImage: "matterlabs/zksolc",      },    },  },  zkSyncDeploy: {    zkSyncNetwork: "https://zksync2-testnet.zksync.dev",    ethNetwork: "goerli", // Can also be the RPC URL of the network (e.g. `https://goerli.infura.io/v3/<API_KEY>`)  },  networks: {    // To compile with zksolc, this must be the default network.    hardhat: {      zksync: true,    },  },  solidity: {    version: "0.8.12",  },};

Create the contracts and deploy folders. The former is the place where all the contracts' *.sol files should be stored, and the latter is the place where all the scripts related to deploying the contract will be put.
Create the contracts/Greeter.sol contract and insert the following code within it:

//SPDX-License-Identifier: Unlicensepragma solidity ^0.8.0;contract Greeter {    string private greeting;    constructor(string memory _greeting) {        greeting = _greeting;    }    function greet() public view returns (string memory) {        return greeting;    }    function setGreeting(string memory _greeting) public {        greeting = _greeting;    }}

Compile the contracts with the following command:

yarn hardhat compile

A artifacts-zk and cache-zk folders were created in the root directory (instead of the regular hardhat's artifacts and cache). These are compilation artifacts, and should not be added to version control.

Create the deployment script in the deploy/deploy.ts:

import { utils, Wallet } from "zksync-web3";import * as ethers from "ethers";import { HardhatRuntimeEnvironment } from "hardhat/types";import { Deployer } from "@matterlabs/hardhat-zksync-deploy";// An example of a deploy script that will deploy and call a simple contract.export default async function (hre: HardhatRuntimeEnvironment) {  console.log(`Running deploy script for the Greeter contract`);  // Initialize the wallet.  const wallet = new Wallet("<WALLET-PRIVATE-KEY>");  // Create deployer object and load the artifact of the contract we want to deploy.  const deployer = new Deployer(hre, wallet);  const artifact = await deployer.loadArtifact("Greeter");  // Deposit some funds to L2 in order to be able to perform L2 transactions.  const depositAmount = ethers.utils.parseEther("0.001");  const depositHandle = await deployer.zkWallet.deposit({    to: deployer.zkWallet.address,    token: utils.ETH_ADDRESS,    amount: depositAmount,  });  // Wait until the deposit is processed on zkSync  await depositHandle.wait();  // Deploy this contract. The returned object will be of a `Contract` type, similarly to ones in `ethers`.  // `greeting` is an argument for contract constructor.  const greeting = "Hi there!";  const greeterContract = await deployer.deploy(artifact, [greeting]);  // Show the contract info.  const contractAddress = greeterContract.address;  console.log(`${artifact.contractName} was deployed to ${contractAddress}`);  // Call the deployed contract.  const greetingFromContract = await greeterContract.greet();  if (greetingFromContract == greeting) {    console.log(`Contract greets us with ${greeting}!`);  } else {    console.error(`Contract said something unexpected: ${greetingFromContract}`);  }  // Edit the greeting of the contract  const newGreeting = "Hey guys";  const setNewGreetingHandle = await greeterContract.setGreeting(newGreeting);  await setNewGreetingHandle.wait();  const newGreetingFromContract = await greeterContract.greet();  if (newGreetingFromContract == newGreeting) {    console.log(`Contract greets us with ${newGreeting}!`);  } else {    console.error(`Contract said something unexpected: ${newGreetingFromContract}`);  }}

After replacing the WALLET-PRIVATE-KEY text with the 0x-prefixed private key of your Ethereum wallet, run the script using the following command:

yarn hardhat deploy-zksync

Paying fees in ERC20 tokens

This section explains how to pay fees in USDC token as an example.

After making sure that the wallet has some Görli USDC on L1, change the depositing code to the following:

const USDC_ADDRESS = "0xd35cceead182dcee0f148ebac9447da2c4d449c4";const USDC_DECIMALS = 6;const deploymentFee = await deployer.estimateDeployFee(artifact, [greeting], USDC_ADDRESS);// Deposit funds to L2.const depositHandle = await deployer.zkWallet.deposit({  to: deployer.zkWallet.address,  token: USDC_ADDRESS,  // We deposit more than the minimal required amount to have funds  // for further iteraction with our smart contract.  amount: deploymentFee.mul(2),  // Unlike ETH, ERC20 tokens require approval in order to deposit to zkSync.  // You can either set the approval in a separate transaction or provide `approveERC20` flag equal to `true`  // and the SDK will initiate approval transaction under the hood.  approveERC20: true,});// Wait until the deposit is processed by zkSync.await depositHandle.wait();

To output the fee in a human-readable format:

const parsedFee = ethers.utils.formatUnits(deploymentFee.toString(), USDC_DECIMALS);console.log(`The deployment will cost ${parsedFee} USDC`);

Please note that the fees on the testnet do not correctly represent the fees on the future mainnet release.

Now pass USDC as the feeToken to the deployment transaction:

const greeterContract = await deployer.deploy(artifact, [greeting], { feeToken: USDC_ADDRESS });

To pay fees in USDC for smart contract interaction, supply the fee token in the customData override:

const setNewGreetingHandle = await greeterContract.setGreeting(newGreeting, {  customData: {    feeToken: USDC_ADDRESS,  },});

Full example:

import { utils, Wallet } from "zksync-web3";import * as ethers from "ethers";import { HardhatRuntimeEnvironment } from "hardhat/types";import { Deployer } from "@matterlabs/hardhat-zksync-deploy";const USDC_ADDRESS = "0xd35cceead182dcee0f148ebac9447da2c4d449c4";const USDC_DECIMALS = 6;// An example of a deploy script that will deploy and call a simple contract.export default async function (hre: HardhatRuntimeEnvironment) {  console.log(`Running deploy script for the Greeter contract`);  // Initialize the wallet.  const wallet = new Wallet("<WALLET-PRIVATE-KEY>");  // Create deployer object and load the artifact of the contract we want to deploy.  const deployer = new Deployer(hre, wallet);  const artifact = await deployer.loadArtifact("Greeter");  const greeting = "Hi there!";  const deploymentFee = await deployer.estimateDeployFee(artifact, [greeting], USDC_ADDRESS);  // Deposit funds to L2  const depositHandle = await deployer.zkWallet.deposit({    to: deployer.zkWallet.address,    token: USDC_ADDRESS,    amount: deploymentFee.mul(2),    approveERC20: true,  });  // Wait until the deposit is processed on zkSync  await depositHandle.wait();  // Deploy this contract. The returned object will be of a `Contract` type, similarly to ones in `ethers`.  // `greeting` is an argument for contract constructor.  const parsedFee = ethers.utils.formatUnits(deploymentFee.toString(), USDC_DECIMALS);  console.log(`The deployment will cost ${parsedFee} USDC`);  const greeterContract = await deployer.deploy(artifact, [greeting], { feeToken: USDC_ADDRESS });  // Show the contract info.  const contractAddress = greeterContract.address;  console.log(`${artifact.contractName} was deployed to ${contractAddress}`);  // Call the deployed contract.  const greetingFromContract = await greeterContract.greet();  if (greetingFromContract == greeting) {    console.log(`Contract greets us with ${greeting}!`);  } else {    console.error(`Contract said something unexpected: ${greetingFromContract}`);  }  // Edit the greeting of the contract  const newGreeting = "Hey guys";  const setNewGreetingHandle = await greeterContract.setGreeting(newGreeting, {    customData: {      feeToken: USDC_ADDRESS,    },  });  await setNewGreetingHandle.wait();  const newGreetingFromContract = await greeterContract.greet();  if (newGreetingFromContract == newGreeting) {    console.log(`Contract greets us with ${newGreeting}!`);  } else {    console.error(`Contract said something unexpected: ${newGreetingFromContract}`);  }}

After replacing the WALLET-PRIVATE-KEY text with the 0x-prefixed private key of the Ethereum wallet, run the script using the following command:

yarn hardhat deploy-zksync

Learn more

New to zksync-web3 SDK? Here is the documentation.
Want to dive deeper into zkSync hardhat plugins? Head straight to the reference.

Future releases

There are two major points of improvements for the plugins which will be released in the future:

Composability with the existing hardhat plugins. Compatibility with other hardhat plugins is planned for future, but has not been a focus yet.
Improved cross-platform support.

Last updated: 8/23/2022, 9:04:05 AM

Hardhat plugins for zkSync 2.0

Reference