What is Hardhat Ignition and how to use it?

Hardhat Ignition is Hardhat's declarative deployment system, providing a more powerful and maintainable deployment approach:

Core Concepts:

1. Modular Deployment

   • Use modules to define deployment logic
   • Support dependencies between modules
   • Declarative configuration instead of imperative scripts

2. Deployment State Management

   • Automatically track deployment state
   • Support incremental deployment
   • Avoid duplicate deployments

Basic Usage:

Create deployment module:

javascript
const { buildModule } = require("@nomicfoundation/hardhat-ignition/modules");

module.exports = buildModule("TokenModule", (m) => {
  const token = m.contract("MyToken", ["MyToken", "MTK", 18]);
  return { token };
});

Advanced Features:

1. Parameterized Deployment

javascript
module.exports = buildModule("TokenModule", (m) => {
  const name = m.getParameter("name", "MyToken");
  const symbol = m.getParameter("symbol", "MTK");
  const token = m.contract("MyToken", [name, symbol, 18]);
  return { token };
});

1. Dependency Management

javascript
module.exports = buildModule("DAppModule", (m) => {
  const token = m.contract("MyToken");
  const sale = m.contract("TokenSale", [token]);
  
  // Call token contract function
  m.call(token, "transferOwnership", [sale]);
  
  return { token, sale };
});

1. Using Existing Contracts

javascript
module.exports = buildModule("Module", (m) => {
  const existingContract = m.contractAt(
    "ExistingContract",
    "0x1234..."
  );
  return { existingContract };
});

Deployment Commands:

bash
# Deploy to local network
npx hardhat ignition deploy ./ignition/modules/Module.js

# Deploy to testnet
npx hardhat ignition deploy ./ignition/modules/Module.js --network sepolia

# Deploy with parameters
npx hardhat ignition deploy ./ignition/modules/Module.js --parameters name:CustomToken,symbol:CTK

# Verify deployment
npx hardhat ignition deploy ./ignition/modules/Module.js --verify

Deployment Plan:

Ignition generates a deployment plan showing the operations to be performed:

bash
npx hardhat ignition plan ./ignition/modules/Module.js

Advantages:

• Declarative configuration is easier to understand
• Automatically handle deployment dependencies
• Support deployment verification
• Better error handling
• Suitable for complex multi-contract deployments
• Facilitates team collaboration