👷 How to deploy smart contracts in Mumbai

.env.example

API_URL="https://matic-mumbai.chainstacklabs.com"
PRIVATE_KEY="0000000000000000000000000000000000000000000000000000000000000000"
POLYGONSCAN_API_KEY="XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
CONTRACT_ADDRESS="0x0000000000000000000000000000000000000000"

deploy.js

main()

async function main () {
  try {
    const HelloWorld = await ethers.getContractFactory('HelloWorld')
    const helloWorld = await HelloWorld.deploy('Hello World!')

    console.info(`Contract deployed to address: ${helloWorld.address}`)
  } catch (err) {
    console.error(err)
  }
}

hardhat.config.js

require('dotenv').config()
require('@nomiclabs/hardhat-ethers')
require('@nomiclabs/hardhat-etherscan')

module.exports = {
  solidity: "0.8.9",
  defaultNetwork: 'maticmum',
  networks: {
    hardhat: {},
    maticmum: {
      url: process.env.API_URL,
      accounts: [`0x${process.env.PRIVATE_KEY}`],
    },
  },
  etherscan: {
    apiKey: process.env.POLYGONSCAN_API_KEY,
  },
}

HelloWorld.sol

// SPDX-License-Identifier: UNLICENSED

pragma solidity >=0.8.9;

contract HelloWorld {
  event UpdatedMessages (string oldMessage, string newMessage);

  string public message;

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

  function update (string memory newMessage) public {
    string memory oldMessage = message;
    message = newMessage;
    emit UpdatedMessages(oldMessage, newMessage);
  }
}

interact.js

const {abi} = require('../artifacts/contracts/HelloWorld.sol/HelloWorld.json')

main()

async function main () {
  try {
    const {API_URL, PRIVATE_KEY, CONTRACT_ADDRESS} = process.env
    const provider = new ethers.providers.JsonRpcProvider(API_URL)
    const wallet = new ethers.Wallet(PRIVATE_KEY, provider)
    const contract = new ethers.Contract(CONTRACT_ADDRESS, abi, wallet)

    const message = await contract.message()
    console.info(`The message is: ${message}`)

    console.info(`Updating the mesaage...`)
    const tx = await contract.update(message + '!')
    await tx.wait()

    const newMessage = await contract.message()
    console.info(`The message is: ${newMessage}`)
  } catch (err) {
    console.error(err)
  }
}

package.json

{
  "name": "mumbai-smart-contract",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "compile": "hardhat compile",
    "deploy": "hardhat run scripts/deploy.js",
    "interact": "hardhat run scripts/interact.js",
    "verify": "source .env && hardhat verify $CONTRACT_ADDRESS \"Hello World!\""
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "@nomiclabs/hardhat-ethers": "^2.1.0",
    "@nomiclabs/hardhat-etherscan": "^3.1.0",
    "ethers": "^5.6.9",
    "hardhat": "^2.10.1"
  },
  "dependencies": {
    "dotenv": "^16.0.1"
  }
}