zkSync Era Hardhat example

This simple project provides an example of how to deploy Solidity contracts to the zkSync Era network using Hardhat.

Prerequisites

• Node.js (tested with v18.16.0)
• yarn (tested with v3.3.1)
• wallet connected to the zkSync Era network (guide)
• zkSync local-setup (optional, for local deployment and testing)

Initialization

Install the dependencies:

yarn install

Make a copy of the .env.example file and rename it to .env:

cp .env.example .env

Edit it with your preferred text editor: add your wallet's private key to the PRIVATE_KEY variable (with 0x prefix) and leave the LOCAL_TESTNET_RICH_WALLET_PRIVATE_KEY as it is.

vim .env

Deployment

Compile the example Greeter contract:

yarn compile

➜  zksync-era-hardhat-example git:(master) ✗ yarn compile
Successfully compiled 1 Solidity file

The deploy command executes the deploy.ts script, that deploys the Greeter.sol contract and calls its greet and setGreeting functions. Deploy the compiled contract to the zkSync local testnet using the following command:

Please make sure that the local testnet is already running before you execute this command!

yarn deploy:local

➜  zksync-era-hardhat-example git:(master) ✗ yarn deploy:local
Running example deploy script for the Greeter contract

Depositing 0.001 ETH from L1 to L2...
Deposit processed.

Greeter contract deployment started...
Greeter contract deployment finished.
Contract address: 0x996462e0eAf00bF6BF0Ea15F29d715C0eD3906F1
Constructor args: 'Hello there!'

Calling the greet function...
Function responded with: Hello there!

The contract can also be deployed to the zkSync Era network:

yarn deploy:era

Verification

To verify the deployed contract's source code on zkcan use the following command:

yarn verify:era <contract-address> <constructor-args>

➜  zksync-era-hardhat-example git:(master) ✗ yarn verify:era 0x996462e0eAf00bF6BF0Ea15F29d715C0eD3906F1 'Hello there!'
Nothing to compile
Your verification ID is: 2950
Contract successfully verified on zkSync block explorer!

Scripts

Other scripts in the deploy directory can be executed using the script command followed by the script's filename (e.g. yarn script:local <filename> or yarn script:era <filename>).

There are 2 examples in addition to the deploy script in the deploy folder, they are explained below.

Deposit

The deposit.ts is an example of how to deposit some funds from L1 to L2. Use the following command to run the deposit.ts script:

yarn script:era deposit

zksync-era-hardhat-example git:(master) ✗ yarn script:era deposit
Running example deploy script for the Greeter contract

Depositing 0.001 ETH from L1 to L2...
========= NOTICE =========
Request-Rate Exceeded  (this message will not be repeated)

The default API keys for each service are provided as a highly-throttled,
community resource for low-traffic projects and early prototyping.

While your application will continue to function, we highly recommended
signing up for your own API keys to improve performance, increase your
request rate/limit and enable other perks, such as metrics and advanced APIs.

For more details: https://docs.ethers.io/api-keys/
==========================
Deposit processed.

It does not really makes sense to do deposits on local testnet because there are several rich wallets with large amount of funds, but of course the script can be executed with the local command as well:

yarn script:local deposit

➜  zksync-era-hardhat-example git:(master) ✗ yarn script:local deposit   
Running example deploy script for the Greeter contract

Depositing 0.001 ETH from L1 to L2...
Deposit processed.

Interact

The interact.ts contains an example of how to interact with an already deployed contract, it shows how to attach to it and how to call its READ and WRITE functions. Use the following command to run the interact.ts script:

Please make sure that before running the script the contractAddress variable has been set to a deployed contract's address.

yarn script:local interact

zksync-era-hardhat-example git:(master) ✗ yarn script:local interact
Running example interact script for the Greeter contract

Attaching to Greeter contract (0x22F4D93be0E8C0C081e74c0d5e697B64eEA007FF)...
Attached to Greeter contract.

Calling the greet function...
Function responded with: Hello There!

Setting a new greeting wit the setGreeting function...
New greeting set.

Calling the greet function...
Function responded with: General Kenobi!

Similarly, to interact with the Greeter contract on the Era network:

yarn script:era interact.ts

Tests

To run the tests use the following command:

Please make sure that the local testnet is already running before you execute this command!

yarn test

➜  zksync-era-hardhat-example git:(master) yarn test        
Successfully compiled 1 Solidity file


  Greeter
    constructor
      ✔ should greet with the initial greeting (1799ms)
    setGreeting
      ✔ should greet with the greeting set by the setGreeting (2914ms)


  2 passing (5s)

Clean

The yarn clean command removes the folder containing the compiled artifacts:

yarn clean

Recompile

If the artifacts folder is not empty, the contract will not be recompiled. Always run the yarn clean followed by yarn compile to recompile:

yarn clean && yarn compile

Credits

This example is based on the zkSync Era Documentation, extends it and makes it easier to get started.