OpenZeppelin Hardhat Upgrades

Hardhat plugin for deploying and managing upgradeable contracts. This package adds functions to your Hardhat scripts so you can deploy and upgrade proxies for your contracts. Depends on ethers.js.

Installation

npm install --save-dev @openzeppelin/hardhat-upgrades
npm install --save-dev @nomiclabs/hardhat-ethers ethers # peer dependencies

And register the plugin in your hardhat.config.js:

// Javascript
require('@openzeppelin/hardhat-upgrades');

// Typescript
import '@openzeppelin/hardhat-upgrades';

Usage in scripts

Proxies

You can use this plugin in a Hardhat script to deploy an upgradeable instance of one of your contracts via the deployProxy function:

// scripts/create-box.js
const { ethers, upgrades } = require("hardhat");

async function main() {
  const Box = await ethers.getContractFactory("Box");
  const box = await upgrades.deployProxy(Box, [42]);
  await box.deployed();
  console.log("Box deployed to:", box.address);
}

main();

This will automatically check that the Box contract is upgrade-safe, set up a proxy admin (if needed), deploy an implementation contract for the Box contract (unless there is one already from a previous deployment), create a proxy, and initialize it by calling initialize(42).

Then, in another script, you can use the upgradeProxy function to upgrade the deployed instance to a new version. The new version can be a different contract (such as BoxV2), or you can just modify the existing Box contract and recompile it - the plugin will note it changed.

// scripts/upgrade-box.js
const { ethers, upgrades } = require("hardhat");

async function main() {
  const BoxV2 = await ethers.getContractFactory("BoxV2");
  const box = await upgrades.upgradeProxy(BOX_ADDRESS, BoxV2);
  console.log("Box upgraded");
}

main();

Note: While this plugin keeps track of all the implementation contracts you have deployed per network, in order to reuse them and validate storage compatibilities, it does not keep track of the proxies you have deployed. This means that you will need to manually keep track of each deployment address, to supply those to the upgrade function when needed.

The plugin will take care of comparing BoxV2 to the previous one to ensure they are compatible for the upgrade, deploy the new BoxV2 implementation contract (unless there is one already from a previous deployment), and upgrade the existing proxy to the new implementation.

Beacon proxies

You can also use this plugin to deploy an upgradeable beacon for your contract with the deployBeacon function, then deploy one or more beacon proxies that point to it by using the deployBeaconProxy function.

// scripts/create-box.js
const { ethers, upgrades } = require("hardhat");

async function main() {
  const Box = await ethers.getContractFactory("Box");

  const beacon = await upgrades.deployBeacon(Box);
  await beacon.deployed();
  console.log("Beacon deployed to:", beacon.address);

  const box = await upgrades.deployBeaconProxy(beacon, Box, [42]);
  await box.deployed();
  console.log("Box deployed to:", box.address);
}

main();

Then, in another script, you can use the upgradeBeacon function to upgrade the beacon to a new version. When the beacon is upgraded, all of the beacon proxies that point to it will use the new contract implementation.

// scripts/upgrade-box.js
const { ethers, upgrades } = require("hardhat");

async function main() {
  const BoxV2 = await ethers.getContractFactory("BoxV2");

  await upgrades.upgradeBeacon(BEACON_ADDRESS, BoxV2);
  console.log("Beacon upgraded");

  const box = BoxV2.attach(BOX_ADDRESS);
}

main();

Usage in tests

You can also use the plugin's functions from your Hardhat tests, in case you want to add tests for upgrading your contracts (which you should!). The API is the same as in scripts.

Proxies

const { expect } = require("chai");

describe("Box", function() {
  it('works', async () => {
    const Box = await ethers.getContractFactory("Box");
    const BoxV2 = await ethers.getContractFactory("BoxV2");
  
    const instance = await upgrades.deployProxy(Box, [42]);
    const upgraded = await upgrades.upgradeProxy(instance.address, BoxV2);

    const value = await upgraded.value();
    expect(value.toString()).to.equal('42');
  });
});

Beacon proxies

const { expect } = require("chai");

describe("Box", function() {
  it('works', async () => {
    const Box = await ethers.getContractFactory("Box");
    const BoxV2 = await ethers.getContractFactory("BoxV2");

    const beacon = await upgrades.deployBeacon(Box);
    const instance = await upgrades.deployBeaconProxy(beacon, Box, [42]);
    
    await upgrades.upgradeBeacon(beacon, BoxV2);
    const upgraded = BoxV2.attach(instance.address);

    const value = await upgraded.value();
    expect(value.toString()).to.equal('42');
  });
});

Learn more

• Refer to the API documentation.
• Also see the main documentation for more info.