Hardhat Chainlink Plugin

Integrates Chainlink into Hardhat projects.

What

This plugin will help you to use the Chainlink protocol inside your tests, scripts & tasks. This is a community initiative, so everyone is welcome to contribute. Start by opening a "Feature Request" issue.

Installation

npm install hardhat-chainlink

# or

yarn add hardhat-chainlink

Import the plugin in your hardhat.config.js:

require("hardhat-chainlink");

Or, if you are using TypeScript, in your hardhat.config.ts:

import "hardhat-chainlink";

Environment extensions

This plugin extends the Hardhat Runtime Environment by adding a chainlink field whose type is ExampleHardhatRuntimeEnvironmentField.

Usage

Full documentation is available at DOCUMENTATION.md. Here are a couple of examples of how to use the plugin.

Example 1 - Get the latest price of ETH

To get the latest price of a given asset, prepare the network field inside hardhat.config file. To add the Goerli Testnet for example, type:

  networks: {
    goerli: {
      url: GOERLI_RPC_URL,
      accounts: [PRIVATE_KEY]
    }
  }

Then import chainlink from hardhat, call the getLatestPrice function and pass it the Aggreagator contract address:

import { chainlink } from "hardhat";

const ethUsdGoerliAggregator: string = `0xD4a33860578De61DBAbDc8BFdb98FD742fA7028e`;
const ethPrice = await chainlink.getLatestPrice(ethUsdGoerliAggregator);

Make sure that your network points to the correct one (Goerli in this example), and double-check that provided aggregator address is correct. For example, if you are writing your tests with the forking feature enabled or developing scripts and tasks on a Goerli network, in which case you will run the above code snippet like this:

npx hardhat run scripts/myScript.ts --network goerli

Example 2 - Create and Manage VRF Subscriptions inside the deployment script

Start by creating VRFv2Consumer.sol contract, which you can get from the Official Chainlink Documentation.

Prepare hardhat.config file for deployment on the Goerli network, for example:

  networks: {
    goerli: {
      url: GOERLI_RPC_URL,
      accounts: [PRIVATE_KEY]
    }
  }

Usually, you will create and manage your subscriptions on the VRF Subscription Management page, but with the plugin, you can automate that process.

Expand your deployment script to include the following:

• Creating new VRF subscriptions
• Funding VRF subscriptions (Make sure to claim LINKs from the faucet)
• Adding new VRF consumers
• And optionally,
  • Getting details about VRF subscriptions
  • Checking if there is a pending outgoing VRF request
  • Removing VRF consumers
  • Canceling VRF subscriptions

// scripts/deploy.ts
import { chainlink, ethers } from "hardhat";

async function main() {
  // NOTE: If you already have an active VRF Subscription, proceed to step 3

  // Step 1: Create a new VRF Subscription
  const vrfCoordinatorAddress = `0x2Ca8E0C643bDe4C2E08ab1fA0da3401AdAD7734D`;
  const { subscriptionId } = await chainlink.createVrfSubscription(
    vrfCoordinatorAddress
  );

  // Step 2: Fund VRF Subscription
  const linkTokenAddress = `0x326C977E6efc84E512bB9C30f76E30c160eD06FB`;
  const amountInJuels = ethers.BigNumber.from(`1000000000000000000`); // 1 LINK
  await chainlink.fundVrfSubscription(
    vrfCoordinatorAddress,
    linkTokenAddress,
    amountInJuels,
    subscriptionId
  );

  // Step 3: Deploy your smart contract
  const VRFv2ConsumerFactory = await ethers.getContractFactory("VRFv2Consumer");
  const VRFv2Consumer = await VRFv2ConsumerFactory.deploy(subscriptionId);
  await VRFv2Consumer.deployed();
  console.log("VRFv2Consumer deployed to:", VRFv2Consumer.address);

  // Step 4: Add VRF Consumer contract to your VRF Subscription
  await chainlink.addVrfConsumer(
    vrfCoordinatorAddress,
    VRFv2Consumer.address,
    subscriptionId
  );
}

main().catch((error) => {
  console.error(error);
  process.exitCode = 1;
});

Run the deployment script by typing:

npx hardhat run scripts/deploy.ts --network goerli

Example 3 - Run Chainlink node on Hardhat network

To run a Chainlink Node on the Hardhat network, you will need to follow a couple of steps.

Step 1

Spin up the Hardhat network by running the following command:

npx hardhat node

Step 2

Open, and if necessary, install Docker Desktop.

Step 3

Spin up a Chainlink node using the following command, which will set up some env variables. Please do not start it from Docker Desktop.

npx hardhat chainlink:run-node

Note

IMPORTANT!

Each time this command runs, it will remove all containers and re-create them (before running docker compose up, we first run docker compose down)

This behavior is analogous to the hardhat EVM node losing all previous history each time it is restarted.

If you want to restart, only pass an additional true parameter (restartOnly) like this npx hardhat chainlink:run-node true

If you visit http://127.0.0.1:6688 in your browser, you should see the Chainlink node login page displayed.

You can use the following credentials to log in to your local Chainlink node:

• username - [email protected]
• password - strongpassword777

To see the available tasks to interact with your node, run:

npx hardhat