Deploy Your First Contract

In this module, you will write, compile, deploy, and interact with your first smart contract on the Rootstock Testnet.

Step 1 — Write the Contract

Create: contracts/HelloRootstock.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

contract HelloRootstock {
    string public message;

    constructor(string memory _message) {
        message = _message;
    }

    function updateMessage(string memory _newMessage) public {
        message = _newMessage;
    }
}

Step 2 — Configure Hardhat

Edit: hardhat.config.js

require("@nomicfoundation/hardhat-toolbox");

module.exports = {
  solidity: "0.8.20",
  networks: {
    rootstock_testnet: {
      url: "https://public-node.testnet.rsk.co",
      chainId: 31,
      accounts: [process.env.PRIVATE_KEY]
    }
  }
};

Add your private key to .env:

PRIVATE_KEY=your_private_key_here

Step 3 — Create Deployment Script

Create: scripts/deploy.js

async function main() {
  const Contract = await ethers.getContractFactory("HelloRootstock");
  const contract = await Contract.deploy("Hello from Rootstock!");

  await contract.waitForDeployment();
  console.log("Contract deployed at:", await contract.getAddress());
}

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

Step 4 — Compile and Deploy

Compile:

npx hardhat compile

Deploy:

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

Expected output:

Compiled successfully
Contract deployed at: 0x1234...abcd

Check contract on the Rootstock Testnet Explorer.

Step 5 — Interact With the Contract

Use Hardhat console:

npx hardhat console --network rootstock_testnet

In console:

const c = await ethers.getContractAt(
  "HelloRootstock",
  "0xYourContractAddress"
);

await c.message(); // read
await c.updateMessage("Updated!"); // write

Summary

You now know how to:

• Write a smart contract
• Configure Hardhat for Rootstock
• Deploy to Testnet
• Interact via terminal

Next: Build Your First dApp