Upgrades Plugins

Integrate upgrades into your existing workflow. Plugins for Hardhat and Foundry to deploy and manage upgradeable contracts on Ethereum.

  • Deploy upgradeable contracts.

  • Upgrade deployed contracts.

  • Manage proxy admin rights.

  • Easily use in tests.

Upgrades Plugins are only a part of a comprehensive set of OpenZeppelin tools for deploying and securing upgradeable smart contracts. Check out the full list of resources.


Installation and Usage

See the documentation for Hardhat Upgrades or Foundry Upgrades.

How the plugins work

The plugins provide functions which take care of managing upgradeable deployments of your contracts.

For example, deployProxy does the following:

  1. Validates that the implementation is upgrade safe.

  2. Deploys the implementation contract. Note that the Hardhat plugin first checks if there is an implementation contract deployed with the same bytecode, and skips this step if one is already deployed.

  3. Creates and initializes the proxy contract, along with a proxy admin (if needed).

And when you call upgradeProxy:

  1. Validates that the new implementation is upgrade safe and is compatible with the previous one.

  2. Deploys the new implementation contract. Note that the Hardhat plugin first checks if there is an implementation contract deployed with the same bytecode, and skips this step if one is already deployed.

  3. Upgrades the proxy to use the new implementation contract.

The Hardhat plugin keeps track of all the implementation contracts you have deployed in an .openzeppelin folder in the project root, as well as the proxy admin. You will find one file per network there. It is advised that you commit to source control the files for all networks except the development ones (you may see them as .openzeppelin/unknown-*.json).

The Foundry plugin does not keep track of implementation contracts, but requires you to define reference contracts in order to validate new versions of implementations for upgrade safety.

Proxy patterns

The plugins support the UUPS, transparent, and beacon proxy patterns. UUPS and transparent proxies are upgraded individually, whereas any number of beacon proxies can be upgraded atomically at the same time by upgrading the beacon that they point to. For more details on the different proxy patterns available, see the documentation for Proxies.

For UUPS and transparent proxies, use deployProxy and upgradeProxy. For beacon proxies, use deployBeacon, deployBeaconProxy, and upgradeBeacon. See the documentation for Hardhat Upgrades and Foundry Upgrades for examples.

Managing ownership

Transparent proxies define an admin address which has the rights to upgrade them. By default, the admin is a proxy admin contract deployed behind the scenes. Keep in mind that the admin of a proxy can only upgrade it, but not interact with the implementation contract. Read Transparent Proxies and Function Clashes for more info on this restriction.

The proxy admin contract also defines an owner address which has the rights to operate it. By default, the proxy admin’s owner is the initialOwner address used during deployment of the transparent proxy if provided, otherwise it is the externally owned account used during deployment. You can change the proxy admin owner by calling the admin.transferProxyAdminOwnership function in the Hardhat plugin, or the transferOwnership function of the proxy admin contract if using Foundry.

Do not reuse an already deployed ProxyAdmin. Before @openzeppelin/contracts version 5.x, the address provided to transparent proxies was an initialAdmin as opposed to an initialOwner of a newly deployed ProxyAdmin. Reusing a ProxyAdmin will disable upgradeability in your contract.

UUPS and beacon proxies do not use admin addresses. UUPS proxies rely on an _authorizeUpgrade function to be overridden to include access restriction to the upgrade mechanism, whereas beacon proxies are upgradable only by the owner of their corresponding beacon.

Once you have transferred the rights to upgrade a proxy or beacon to another address, you can still use your local setup to validate and deploy the implementation contract. The plugins include a prepareUpgrade function that will validate that the new implementation is upgrade-safe and compatible with the previous one, and deploy it using your local Ethereum account. You can then execute the upgrade itself from the admin or owner address. You can also use the defender.proposeUpgrade or defender.proposeUpgradeWithApproval functions to automatically set up the upgrade in OpenZeppelin Defender.