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Deploy Contract ​

The process of deploying a contract to MIDL is similar to deploying on EVM-compatible networks, with the key difference that every deployment and write transaction requires interaction with Bitcoin L1. For the best experience, we recommend using the @midl/hardhat-deploy plugin together with hardhat-deploy.

You can find advanced examples in this repo.

Overview ​

In this guide, you will deploy a simple Solidity smart contract to the MIDL network. The example contract is a basic storage contract that allows you to store and retrieve a value on-chain. This demonstrates the core workflow for deploying and interacting with contracts on MIDL.

The steps covered in this guide are:

  • Project Setup: Initialize a new Hardhat project and install the required dependencies for MIDL.
  • Configuration: Configure Hardhat and the MIDL deploy plugin for your environment.
  • Write the Contract: Create a simple storage contract in Solidity.
  • Deployment Script: Write a script to deploy your contract using the MIDL Hardhat plugin.
  • Deploy the Contract: Run the deployment, which will require confirmation on Bitcoin Layer 1.
  • Verify: Verify your contract on the block explorer after deployment.

Create a New Project ​

First, create a new project using the following commands:

bash
mkdir hardhat-midl
cd hardhat-midl
pnpm init
pnpm add -D hardhat @midl/hardhat-deploy hardhat-deploy @midl/executor

Initialize Hardhat ​

Run the following command to initialize Hardhat:

bash
pnpx hardhat init

Choose Create a TypeScript project:

bash
? 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
  1. Press Enter to confirm the default options in the project root.
  2. Press Enter again to add a .gitignore file.
  3. Press Enter to install the sample's project dependencies.

WARNING

It is important to clean up the default files created by Hardhat as Hardhat ignition is not compatible with MIDL. You can do this by running the following command:

bash
rm -rf ignition test contracts/**

Update hardhat.config.ts ​

The deployment of contracts on MIDL requires Bitcoin account, which is defined by the MNEMONIC variable. This variable should be set to a valid BIP39 mnemonic phrase that will be used to derive the Bitcoin account.

TIP

To define the MNEMONIC variable, you can run the following command:

bash
npx hardhat vars set MNEMONIC

and then paste your mnemonic when prompted.

See the official Hardhat documentation for more details.

Add the following lines to your hardhat.config.ts. For more configuration options, refer to the plugin documentation.

ts
import "@typechain/hardhat";
import "@midl/hardhat-deploy";
import "hardhat-deploy";
import "@nomicfoundation/hardhat-verify";
import { vars, type HardhatUserConfig } from "hardhat/config";
import { midlRegtest } from "@midl/executor";

const config: HardhatUserConfig = {
  solidity: "0.8.28",
  midl: {
    networks: {
      default: {
        mnemonic: vars.get("MNEMONIC"),
        confirmationsRequired: 1,
        btcConfirmationsRequired: 1,
      },
    },
  },
  networks: {
    default: {
      url: midlRegtest.rpcUrls.default.http[0],
      chainId: midlRegtest.id,
    },
  },
  etherscan: {
    apiKey: {
      "midl-regtest": "empty",
    },
    customChains: [
      {
        network: "midl-regtest",
        chainId: 777,
        urls: {
          apiURL: "https://blockscout.regtest.midl.xyz/api",
          browserURL: "https://blockscout.regtest.midl.xyz",
        },
      },
    ],
  },
};

export default config;

Create a New Contract ​

Create a new contract in the contracts directory:

bash
touch contracts/SimpleStorage.sol

Add the following code to contracts/SimpleStorage.sol:

solidity
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract SimpleStorage {
    string private message;

    event MessageUpdated(string newMessage);

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

    function setMessage(string memory newMessage) public {
        message = newMessage;
        emit MessageUpdated(newMessage);
    }

    function getMessage() public view returns (string memory) {
        return message;
    }
}

Create a Deploy Script ​

Create a new deploy script in the deploy directory:

bash
mkdir deploy
touch deploy/00_deploy_SimpleStorage.ts
typescript
import type { DeployFunction } from "hardhat-deploy/types";

const deploy: DeployFunction = async (hre) => {
  /**
   * Initializes the MIDL hardhat deploy SDK
   */
  await hre.midl.initialize();

  /**
   * Add the deploy contract transaction intention
   */
  await hre.midl.deploy("SimpleStorage", {
    args: ["Hello from MIDL!"],
  });

  /**
   * Sends the BTC transaction and EVM transaction to the network
   */
  await hre.midl.execute();
};

deploy.tags = ["main", "TERC20"];

export default deploy;

Deploy the Contract ​

WARNING

Make sure you have Bitcoin on Regtest. You can claim some at the faucet or by contacting us directly on Discord. To get your Bitcoin account address, you can run the following command:

bash
pnpm hardhat midl:address

Output example:

Bitcoin Address: bcrt1qf3r47tdpkn4rq6gq8kkfhw7l60q08lemmahgmf (p2wpkh)
EVM Address: 0x0130ddAA9bEc9552F11F17792b4EEED2b7d5E8Dd

Run the following command to deploy the contract:

bash
pnpm hardhat deploy

After the deployment is complete, you will see a folder named deployments in your project directory. Inside this folder, you will find a JSON file containing the contract address and other information.

Verify source code ​

Now that your contract is deployed, you can verify it's source code on the block explorer using the following command:

bash
pnpm hardhat verify REPLACE_WITH_CONTRACT_ADDRESS "Hello from MIDL" --network default

Successful verification will return the link to the contract on the block explorer.

Advanced Usage ​

Midl's hardhat-deploy offers more functionality than just deploying or writing to contracts. You can find commonly used functions here and examples in this repo.