Skip to main content

Gearbox SDK and Mainnet Forking

After we've set up Hardhat,

we will import the Gearbox SDK into our codebase. We will then use Hardhat to fork the Ethereum Mainnet.

Gearbox SDK ⚙️🧰​

First of all, we need to import the Gearbox SDK into our project.

bash
npm install --save-dev @gearbox-protocol/sdk
bash
npm install --save-dev @gearbox-protocol/sdk

Next, we'll install some additional dependencies:

bash
npm install --save-dev dotenv hardhat-abi-exporter hardhat-contract-sizer
bash
npm install --save-dev dotenv hardhat-abi-exporter hardhat-contract-sizer

We will replace the content of hardhat.config.ts to set some parameters for using Gearbox SDK and forking mainnet.

info

We are adding the Hardhat network here

hardhat.config.ts
tsx
import * as dotenv from "dotenv";
import { HardhatUserConfig, task } from "hardhat/config";
import "@nomiclabs/hardhat-etherscan";
import "@nomiclabs/hardhat-waffle";
import "@typechain/hardhat";
import "hardhat-gas-reporter";
import "solidity-coverage";
import { LOCAL_NETWORK, MAINNET_NETWORK } from "@gearbox-protocol/sdk";
dotenv.config();
// This is a sample Hardhat task. To learn how to create your own go to
// https://hardhat.org/guides/create-task.html
task("accounts", "Prints the list of accounts", async (taskArgs, hre) => {
  const accounts = await hre.ethers.getSigners();
  for (const account of accounts) {
    console.log(account.address);
  }
});
// You need to export an object to set up your config
// Go to https://hardhat.org/config/ to learn more
const config: HardhatUserConfig = {
  solidity: "0.8.4",
  networks: {
    hardhat: {
      chainId: LOCAL_NETWORK,
      initialBaseFeePerGas: 0,
    },
    mainnet: {
      url: process.env.ETH_MAINNET_PROVIDER,
      accounts: [KOVAN_PRIVATE_KEY],
      chainId: MAINNET_NETWORK,
    },
    ropsten: {
      url: process.env.ROPSTEN_URL || "",
      accounts:
        process.env.PRIVATE_KEY !== undefined ? [process.env.PRIVATE_KEY] : [],
    },
  },
  gasReporter: {
    enabled: process.env.REPORT_GAS !== undefined,
    currency: "USD",
  },
  etherscan: {
    apiKey: process.env.ETHERSCAN_API_KEY,
  },
};
export default config;
hardhat.config.ts
tsx
import * as dotenv from "dotenv";
import { HardhatUserConfig, task } from "hardhat/config";
import "@nomiclabs/hardhat-etherscan";
import "@nomiclabs/hardhat-waffle";
import "@typechain/hardhat";
import "hardhat-gas-reporter";
import "solidity-coverage";
import { LOCAL_NETWORK, MAINNET_NETWORK } from "@gearbox-protocol/sdk";
dotenv.config();
// This is a sample Hardhat task. To learn how to create your own go to
// https://hardhat.org/guides/create-task.html
task("accounts", "Prints the list of accounts", async (taskArgs, hre) => {
  const accounts = await hre.ethers.getSigners();
  for (const account of accounts) {
    console.log(account.address);
  }
});
// You need to export an object to set up your config
// Go to https://hardhat.org/config/ to learn more
const config: HardhatUserConfig = {
  solidity: "0.8.4",
  networks: {
    hardhat: {
      chainId: LOCAL_NETWORK,
      initialBaseFeePerGas: 0,
    },
    mainnet: {
      url: process.env.ETH_MAINNET_PROVIDER,
      accounts: [KOVAN_PRIVATE_KEY],
      chainId: MAINNET_NETWORK,
    },
    ropsten: {
      url: process.env.ROPSTEN_URL || "",
      accounts:
        process.env.PRIVATE_KEY !== undefined ? [process.env.PRIVATE_KEY] : [],
    },
  },
  gasReporter: {
    enabled: process.env.REPORT_GAS !== undefined,
    currency: "USD",
  },
  etherscan: {
    apiKey: process.env.ETHERSCAN_API_KEY,
  },
};
export default config;
info

As we can see, hardhat.config.file will read the .env file. Thus we create a .env file in the root of the project folder. For supporting mainnet forking, we only need ETH_MAINNET_PROVIDER.

  ETH_MAINNET_PROVIDER=https://eth-mainnet.alchemyapi.io/v2/YOUR_MAINNET_API_KEY
  ETH_MAINNET_PROVIDER=https://eth-mainnet.alchemyapi.io/v2/YOUR_MAINNET_API_KEY
note

To use this feature you need to connect to an archive node. We recommend using Alchemy. Please get your mainnet API key from there, once you've created an account.

Mainnet Forking​

We've set up a working environment with our tooling now. We will now move on to forking the Ethereum Mainnet.

We'll set up a script in our script folder.

bash
cd scripts
bash
cd scripts

Then create a script file, let's call it fork.sh. It exports the configuration in .env file and use Hardhat to fork the Ethereum Mainnet.

fork.sh
shell
set -o allexport; source ./.env; set +o allexport;
npx hardhat node --fork $ETH_MAINNET_PROVIDER
fork.sh
shell
set -o allexport; source ./.env; set +o allexport;
npx hardhat node --fork $ETH_MAINNET_PROVIDER

We may want to use yarn or npm to run this fork.sh file, so add the following to the package.json file.

json
"scripts": {
    "fork": "scripts/fork.sh"
}
json
"scripts": {
    "fork": "scripts/fork.sh"
}

Now we can fork mainnet by running

bash
npm run fork
bash
npm run fork