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Using Harmony-JS

This page describes in detail how to deploy a smart contract on to Harmony using an example

The smart contract demo example used in this tutorial can be found in the following repository.

is a Truffle box that will get you quickly up and running deploying smart contracts on Harmony using Truffle & native Ethereum tooling.

Setup

Pre-Requisites

The following tools need to be installed:

NodeJS v12+
Node Package Manager (npm)

Globally Truffle Installation

npm install -g truffle

You might be require to provide super user privileges to install it.

Project Setup

Navigate to the directory where you want to setup you project. For this guide we will be using "demo" as the project name.

truffle init demo
cd demo

Installing Dependencies

npm install --save @harmony-js/core
npm install --save @harmony-js/utils
npm install --save tslib
npm install --save dotenv

(Optional) Install Additional Dependencies if required. We wont be using this for this demo.

npm install openzeppelin-solidity -s

Create a .env file in the project root directory and put your mnemonic code, private key, and rpc url in it. We will be using the following structure for our demo.

//LOCAL
LOCAL_PRIVATE_KEY=<YOUR_PRIVATE_KEY>
LOCAL_MNEMONIC=<YOUR_MNEMONIC_CODE>
LOCAL_0_URL='http://localhost:9500'

//TESTNET
TESTNET_PRIVATE_KEY=<YOUR_PRIVATE_KEY>
TESTNET_MNEMONIC=<YOUR_MNEMONIC_CODE>
TESTNET_0_URL='https://api.s0.b.hmny.io'
TESTNET_1_URL='https://api.s1.b.hmny.io'

//MAINNET
MAINNET_PRIVATE_KEY=<YOUR_PRIVATE_KEY>
MAINNET_MNEMONIC=<YOUR_MNEMONIC_CODE>
MAINNET_0_URL='https://api.s0.t.hmny.io'

GAS_LIMIT=3321900
GAS_PRICE=1000000000

Configuring Truffle

In the project root directory, there is a file truffle-config.js and copy paste the following configuration.

require("dotenv").config();
const { TruffleProvider } = require("@harmony-js/core");

//Local
const local_mnemonic = process.env.LOCAL_MNEMONIC;
const local_private_key = process.env.LOCAL_PRIVATE_KEY;
const local_url = process.env.LOCAL_0_URL;

//Testnet
const testnet_mnemonic = process.env.TESTNET_MNEMONIC;
const testnet_private_key = process.env.TESTNET_PRIVATE_KEY;
const testnet_url = process.env.TESTNET_0_URL;

//Mainnet
const mainnet_mnemonic = process.env.MAINNET_MNEMONIC;
const mainnet_private_key = process.env.MAINNET_PRIVATE_KEY;
const mainnet_url = process.env.MAINNET_0_URL;

//GAS - Currently using same GAS accross all environments
gasLimit = process.env.GAS_LIMIT;
gasPrice = process.env.GAS_PRICE;

module.exports = {
  networks: {
    local: {
      network_id: "2", // Any network (default: none)
      provider: () => {
        const truffleProvider = new TruffleProvider(
          local_url,
          { memonic: local_mnemonic },
          { shardID: 0, chainId: 2 },
          { gasLimit: gasLimit, gasPrice: gasPrice }
        );
        const newAcc = truffleProvider.addByPrivateKey(local_private_key);
        truffleProvider.setSigner(newAcc);
        return truffleProvider;
      },
    },
    testnet: {
      network_id: "2", // Any network (default: none)
      provider: () => {
        const truffleProvider = new TruffleProvider(
          testnet_url,
          { memonic: testnet_mnemonic },
          { shardID: 0, chainId: 2 },
          { gasLimit: gasLimit, gasPrice: gasPrice }
        );
        const newAcc = truffleProvider.addByPrivateKey(testnet_private_key);
        truffleProvider.setSigner(newAcc);
        return truffleProvider;
      },
    },
    mainnet0: {
      network_id: "1", // Any network (default: none)
      provider: () => {
        const truffleProvider = new TruffleProvider(
          mainnet_url,
          { memonic: mainnet_mnemonic },
          { shardID: 0, chainId: 1 },
          { gasLimit: gasLimit, gasPrice: gasPrice }
        );
        const newAcc = truffleProvider.addByPrivateKey(mainnet_private_key);
        truffleProvider.setSigner(newAcc);
        return truffleProvider;
      },
    },
  }
};

Compile & Deploy

This section covers writing a custom smart contract and deploying it on Harmony Testnet.

Writing our first Counter Smart Contract

In the contracts folder create a new file Counter.sol and add the following code block to it:

In the migrations folder create another new file called 2_Counter.js and add the following code block:

Checking the Solidity Smart Contract

If all was done correctly you should see something like this:

Deployment

Demo: Deploying an Ethereum Smart Contract on Harmony

Since Harmony is fully EVM-compatible (Ethereum Virtual Machine), it makes it really easy to port existing contracts to Harmony. Here's a short demo on how to port an existing Ethereum smart contract to the Harmony testnet:

If you have an idea that you'd like to deploy on the Harmony Protocol, you might be interested in learning about the Harmony Grant Program.