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Deploying smart contract using Private Network

Introduction ​

In this guide, we will walk you through the process of deploying a Greeter contract on a private Kaia network using Kaia Hardhat Utils. By following this guide, you'll learn how to:

  • Set up a Hardhat project.
  • Launch a private network simulating the Kairos Testnet.
  • Utilize Hardhat utils to deploy smart contracts on this private network.

Prerequisite ​

To follow this tutorial, the following are the prerequisites:

  • Code editor: a source-code editor such as VS Code.
  • Docker: if you don’t have docker installed, kindly install using this link
  • Node.js and npm: Node version 18 and above.

Setting Up your Development Environment ​

In this section, we will install hardhat, Kaia hardhat utils and other necessary dependencies needed for bootstrapping our project.

Step 1: Create a project directory


mkdir $HOME/kaia-greeter
cd kaia-greeter

Step 2: Initialize an npm project


npm init -y

Step 3: Install hardhat, hardhat-utils and other dependencies

  • Copy and paste the code below in your terminal to install hardhat and hardhat-utils

npm i hardhat @klaytn/hardhat-utils

  • Copy and paste the code below to install other dependencies

npm install @nomiclabs/hardhat-ethers hardhat-deploy dotenv

note

The hardhat-utils plugin depends on hardhat-ethers and hardhat-deploy plugin. Make sure to require or import them in your hardhat.config.js or hardhat.config.ts.

info

(Recommended) Install hardhat shorthand. But you can still use the tasks with npx hardhat.


npm install hardhat-shorthand --save

Step 4: Initialize a hardhat project

Run the command below to initiate an hardhat project:


npx hardhat init

For this guide, you'll be selecting "create an empty hardhat.config.js" project as seen below:


888 888 888 888 888
888 888 888 888 888
8888888888 8888b. 888d888 .d88888 88888b. 8888b. 888888
888 888 "88b 888P" d88" 888 888 "88b "88b 888
888 888 .d888888 888 888 888 888 888 .d888888 888
888 888 888 888 888 Y88b 888 888 888 888 888 Y88b.
888 888 "Y888888 888 "Y88888 888 888 "Y888888 "Y888
👷 Welcome to Hardhat v2.22.9 👷‍
? What do you want to do? …
Create a JavaScript project
Create a TypeScript project
Create a TypeScript project (with Viem)
❯ Create an empty hardhat.config.js
Quit

Step 5: Create a .env file

Now create your .env file in the project folder. This file helps us load environment variables from an .env file into process.env.

Copy and paste this command in your terminal to create a .env file


touch .env

Configure your .env file to look like this:


PRIVATE_KEY="COPY & PASTE ANY OF THE PRIVATE KEY PROVIDED BY LOCAL PRIVATE NETWORK"

note

When you launch the private network in the next section, you will be able to access the private key provided by the local network.

Step 6: Setup Hardhat Configs

Modify your hardhat.config.js with the following configurations:


require("@nomiclabs/hardhat-ethers");
require("hardhat-deploy");
require("@klaytn/hardhat-utils");
require('dotenv').config()
const accounts = [
process.env.PRIVATE_KEY
];
/** @type import('hardhat/config').HardhatUserConfig */
module.exports = {
solidity: "0.8.24",
networks: {
localhost: {
url: process.env.RPC_URL || "http://localhost:8545",
accounts: accounts,
},
kairos: {
url: process.env.RPC_URL || "https://public-en-kairos.node.kaia.io",
accounts: accounts,
},
kaia: {
url: process.env.RPC_URL || "https://public-en.node.kaia.io",
accounts: accounts,
}
},
namedAccounts: {
deployer: {
default: 0, // here this will by default take the first account as deployer
},
},
};

Launching the Private Network ​

To launch a private network, the hardhat utils plugin provides us a task to easily launch one viz:


hh klaytn-node

Attaching Console ​

The private network comes with a JavaScript console. From the console command line, you can initiate part of Kaia API calls to your network. To attach to the JavaScript console, execute the following command:


hh klaytn-node --attach

Result

Welcome to the Kaia JavaScript console!
instance: Klaytn/v0.9.2/linux-amd64/go1.22.1
datadir: /klaytn
modules: admin:1.0 debug:1.0 eth:1.0 governance:1.0 istanbul:1.0 kaia:1.0 net:1.0 personal:1.0 rpc:1.0 txpool:1.0 web3:1.0

note

Type kaia or personal to get the list of available functions.

Checking the Balance in your account ​

When we launched the private network, it provided us with a list of accounts, private key and pre-funded values for each account.

To see the balance of the account, execute the following command.


kaia.getBalance("0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266")

Configuring hardhat network environment ​

Now that we are running a stand alone local network, which external clients (wallets, dApp) can connect to, we need to configure hardhat to use this network by running this command:


export HARDHAT_NETWORK=localhost
hh accounts


hh --network localhost accounts

Creating KaiaGreeter Smart Contract ​

In this section, you will create a KaiaGreeter smart contract.

Step 1: Create a new folder named contracts folder in the Explorer pane, click the New File button and create a new file named KaiaGreeter.sol

Step 2: Open the file and paste the following code:


// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.0;
import "hardhat/console.sol";
contract KaiaGreeter {
uint256 totalGreetings;
constructor() {
console.log("Yo yo, Welcome to Kaia");
}
function greet() public {
totalGreetings += 1;
console.log(msg.sender, "says hello kaia!");
}
function getTotalGreetings() public view returns (uint256) {
console.log("We have %d total waves!", totalGreetings);
return totalGreetings;
}
}

Deploying KaiaGreeter ​

In this section we will use the hardhat-deploy plugin to deploy our contracts.

Step 1: In the Explorer pane, Create a new folder called deploy and click the New File button to create a new file named deploy.js.

Step 2: Copy and paste the following code inside the file.


module.exports = async ({getNamedAccounts, deployments}) => {
const {deploy} = deployments;
const {deployer} = await getNamedAccounts();
await deploy('KaiaGreeter', {
from: deployer,
args: [],
log: true,
});
};
module.exports.tags = ['KaiaGreeter'];

Step 3: In the terminal, run the following command which tells Hardhat to deploy your KaiaGreeter contract on the private network.


hh deploy

Verifying transaction using Block Explorer ​

Step 1: To verify our transactions using a local blockscout explorer, run the command below in a new terminal:


hh explorer --network localhost


[+] Using env: {
DOCKER_RPC_HTTP_URL: 'http://host.docker.internal:8545/',
DOCKER_LISTEN: '0.0.0.0:4000',
DOCKER_DISABLE_TRACER: 'false',
DOCKER_DEBUG: '0'
}
[+] Open in the browser: http://localhost:4000
Network blockscout_default Creating
Network blockscout_default Created
Container blockscout-db-1 Creating
Container blockscout-frontend-1 Creating
Container blockscout-smart-contract-verifier-1 Creating
Container blockscout-redis_db-1 Creating
Container blockscout-smart-contract-verifier-1 Created
Container blockscout-db-1 Created
Container blockscout-frontend-1 Created
Container blockscout-redis_db-1 Created
Container blockscout-backend-1 Creating
Container blockscout-backend-1 Created
Container blockscout-frontend-1 Starting
Container blockscout-redis_db-1 Starting
Container blockscout-smart-contract-verifier-1 Starting
Container blockscout-db-1 Starting
Container blockscout-db-1 Started
Container blockscout-redis_db-1 Started
Container blockscout-smart-contract-verifier-1 Started
Container blockscout-backend-1 Starting
Container blockscout-frontend-1 Started
Container blockscout-backend-1 Started

Step 2: To access this block explorer, open up http://localhost:4000 in your browser.

Step 3: Copy and paste the deployed contract address in the search field and press Enter. You should see the recently deployed contract.

Interacting with deployed contract ​

using hardhat utils contract task​

  1. To call a read-only function of the deployed contract, run the command below:

hh call KaiaGreeter getTotalGreetings

  1. To send a function invoking transaction to the deployed contract, run the command below:

hh send KaiaGreeter greet

Result

sent KaiaGreeter#greet (tx: 0xc0bd25ffb594c13d5ae1f77f7eb02f2978013c69f9f6e22694b76fa26c329e85)...ok (block 2837, gas used: 47457)

using Kaia SDK​

Step 1: To interact with the deployed contract using Kaia SDK, you need to install Kaia SDK by running this command:


npm install --save @kaiachain/ethers-ext

Step 2: In the Explorer pane, Create a new folder called "utils" and click the New File button to create a new file named kaia-sdk.js in the utils folder.

Step 3: Copy and paste the following code inside the file.


const { JsonRpcProvider, Wallet } = require("@kaiachain/ethers-ext");
const { ethers } = require("ethers");
require('dotenv').config()
const provider = new JsonRpcProvider("http://127.0.0.1:8545/")
const privKey = process.env.PRIVATE_KEY;
const signer = new ethers.Wallet(privKey, provider);
const contractAddress = "0x5FbDB2315678afecb367f032d93F642f64180aa3" // PASTE DEPLOYED CONTRACT ADDRESS;
const KaiaGreeterABI = require("../artifacts/contracts/KaiaGreeter.sol/KaiaGreeter.json").abi;
async function getCode(ca) {
const tx = await provider.getCode(ca);
console.log(tx);
}
async function greet(ca) {
const klaytnGreeter = new ethers.Contract(ca, KaiaGreeterABI, signer);
const tx = await klaytnGreeter.greet();
console.log( tx);
}
async function getTotalGreetings(ca) {
const klaytnGreeter = new ethers.Contract(ca, KaiaGreeterABI, provider);
const value = await klaytnGreeter.getTotalGreetings();
console.log(value.toString());
}
// getCode(contractAddress);
getTotalGreetings(contractAddress);
// greet(contractAddress);

Step 4: To execute any of the functions declared in this file, make sure to uncomment them as we did for the getTotalGreetings() function, then run the following command in your terminal.


node utils/kaia-sdk.js

For a more in-depth guide on hardhat-utils, please refer to hardhat-utils github. Also, you can find the full implementation of the code for this guide on GitHub

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