A complete list of all available proxy contracts and related utilities, with documentation relevant for low-level use without Upgrades Plugins. Thats it. This guide will walk you through the process of upgrading a smart contract in production secured by a multisig wallet, using Defender Admin as an interface, and Hardhat scripts behind the scenes. Creating and approving upgrade proposals with OpenZeppelin Defender Automating smart contract upgrade proposals with Upgrade Plugins and the Defender API You can watch the video, view the slides, upgrade the example contract. This is because even though we did initialize the state variable correctly, the value of the variable simply isnt stored in the implementation contract. In your migrations you are actually deploying a new contract using deployProxy. Keep in mind that the admin of a proxy can only upgrade it, but not interact with the implementation contract. You just successfully installed and initialized Hardhat. The function __{ContractName}_init_unchained found in every contract is the initializer function minus the calls to parent initializers, and can be used to avoid the double initialization problem, but doing this manually is not recommended. The hardhat-upgrades package is the plugin that allows us to call the function that deploys upgradeable contracts. Kudos if you were able to follow the tutorial up to here. Fortunately, this limitation only affects state variables. If you have any feedback, feel free to reach out to us via Twitter. When we perform an upgrade, we deploy a new implementation contract and point the proxy contract to the new implementation. If you dont know where to start we suggest to start with. Well be using VScode and will continue running our commands in the embedded terminal. To obtain a key, from the Defender menu in the top right corner select Team API Keys and then select Create API Key. In this way we learn about some of the capabilities of the Upgrades Plugins for Hardhat and Truffle, and how they can . Upgrade our Box using the Upgrades Plugins. I see know that OpenZeppelin is at version 3.4.0. In this section, we will create two basic smart contracts. We are now ready to configure our deployment tools. Well, thats because we need to tell the block explorer that the contract indeed is a proxy, even though the explorer usually already suspects it. Only code is stored in the implementation contract itself, while the state is maintained by the TransparentUpgradeableProxy contract. I am worried that I will end up using the old ZOS contract library by accident, and I see that there have been several important fixes, including the now fixed problem of ZOS returning a zero address when an error occurred: After thorough assessment of all submissions, we are happy to share the winners of this years Solidity Underhanded Contest! This would effectively break all contract instances in your project. Since well be working with upgradeable smart contracts, we will need to install two more dependencies. This can be an array of uint256 so that each element reserves a 32 byte slot. Once we transferred control of upgrades (ownership of the ProxyAdmin) to our multisig, we can no longer simply upgrade our contract. As such, it is not allowed to use either selfdestruct or delegatecall in your contracts. Our globally distributed, auto-scaling, multi-cloud network will carry you from MVP all the way to enterprise. Make sure that all initial values are set in an initializer function as shown below; otherwise, any upgradeable instances will not have these fields set. Create another file in the contracts folder, and name it contractV2.sol. Listed below are four patterns. Why Upgrades? To do this add the plugin in your hardhat.config.js file as follows. You can rest with the confidence that, should a bug appear, you have the tools to modify your contract and change it. Change the value of gnosisSafe to your Gnosis Safe address. OpenZeppelin Upgradeable Contracts A variant of the popular OpenZeppelin Contracts library, with all of the necessary changes specific to upgradeable contracts. Sign up below! Both plugins provide functions which take care of managing upgradeable deployments of your contracts. upgradeProxy will create the following transactions: Deploy the implementation contract (our BoxV2 contract). Deploy the ProxyAdmin contract (the admin for our proxy). The package replicates the structure of the main OpenZeppelin Contracts package, but every file and contract has the suffix Upgradeable. Subscribe to our newsletter for more articles and guides on Ethereum. This may be the desired behavior if the new variable is semantically the same as the old one: And if you remove a variable from the end of the contract, note that the storage will not be cleared. How cool is that! And it also allows us to change the code by just having the proxy delegate to a different implementation contract. This means that the implementation contract does not maintain its own state and actually relies on the proxy contract for storage. And this process is the same regardless of whether you are working on a local blockchain, a testnet, or the main network. The US Navy has awarded BAE Systems a $145-million contract to maintain and upgrade the USS Nitze (DDG 94) Arleigh Burke-class guided-missile destroyer. Upgrades Plugins Plugins for Hardhat and Truffle that abstract away the complexities of upgrades, while running automated security checks to ensure successful upgrades. We will use the Truffle console to interact with our upgraded Box contract. Thus, we don't need to build the proxy patterns ourselves. If your contract is going to be deployed with upgradeability, such as using the OpenZeppelin Upgrades Plugins, you will need to use the Upgrade Safe variant of OpenZeppelin Contracts. Run our deploy.js and deploy to the Rinkeby network. Lines 3-5: We then create a function to deploy our V1 smart contract and then print a status message. Read Transparent Proxies and Function Clashes for more info on this restriction. Create and Deploy an Upgradeable Smart Contract, npx hardhat verify --contract "contracts/contractV1.sol:V1" --network mumbai, "Insert your proxy contract address here", npx hardhat run --network mumbai scripts/upgradeV1.js, npx hardhat verify --contract "contracts/contractV2.sol:V2" --network mumbai, Different Ways to Verify Your Smart Contract Code, Call Another Smart Contract From Your Solidity Code, Create a Smart Contract Factory in Solidity using Hardhat, Create and Deploy a Smart Contract With Hardhat, Setup Local Development Environment for Solidity, Create a Secure Smart Contract using Vyper, Write an Ethereum Smart Contract Using Solidity, Write an Ethereum Smart Contract Using Vyper, Integrate Your Svelte App with a Smart Contract, "An Introduction to Upgradeable Smart Contracts", Create an upgradeable smart contract using OpenZeppelins Plug-ins for Hardhat, Compile and deploy the contract on the Mumbai Testnet using Hardhat, Verify the contract using Polygonscan API, Upgrade the contract and verify the results, NPM (Node Package Manager) and Node.js (Version 16.15 recommended), MetaMask with the Polygon Mumbai Testnet selected (you can learn how to add the network to your wallet, MATIC tokens on Mumbai Testnet (you can get some at this, Knowledge of upgradeable smart contracts. 1. These come up when writing both the initial version of contract and the version well upgrade it to. So whats happening here? OpenZeppelin/openzeppelin-contracts-upgradeable, Use with multiple inheritance requires special attention. This means you should not be using these contracts in your OpenZeppelin Upgrades project. In this new file, paste the following code: Look back to contract V1 and see what the initialValue function does. A Hardhat project with Hardhat Upgrades plugin, Hardhat Defender, ethers.js and dotenv installed. We will use the following hardhat.config.js for deploying to Rinkeby. @nomiclabs/hardhat-etherscan is a hardhat plugin that allows us to verify our contracts in the blockchain. OpenZeppelin has released a new set of tools in partnership with Truffle, Nomic Labs and Gnosis Safe to make it easy to deploy and manage upgradeable smart contracts. Using the run command, we can upgrade the Box contract on the development network. How to create an upgradeable smart contract using OpenZeppelin SDK | by Paulina Baszkiewicz | Coinmonks | Medium Write Sign up Sign In 500 Apologies, but something went wrong on our end. Due to technical limitations, when you upgrade a contract to a new version you cannot change the storage layout of that contract. Initializers Using the upgradeable smart contract approach, if there is an error, faulty logic or a missing feature in your contract, a developer has the option to upgrade this smart contract and deploy a new one to be used instead. Thats it! We will create a migration script to deploy our upgradeable Box contract using deployProxy. However, nothing prevents a malicious actor from sending transactions to the logic contract directly. Migrations consist of JavaScript files and a special Migrations contract to track migrations on-chain. We can simply get a free trial node from QuickNode, which is much better than investing time looking at different custom configs to launch your own node. Check if there is an implementation contract deployed with the same bytecode, and deploy one if not. Here you will create an API key that will help you verify your smart contracts on the blockchain. When writing upgradeable contracts we need to use the Upgradeable version of OpenZeppelin Contracts, see: https://docs.openzeppelin.com/contracts/3.x/upgradeable, If you have an existing upgradeable project, then you can migrate from OpenZeppelin CLI to Upgrades Plugins using the following guide: https://docs.openzeppelin.com/upgrades-plugins/1.x/migrate-from-cli. Report by Santiago Palladino, Lead Developer at OpenZeppelin A survey of the different Ethereum smart contract upgrade patterns and strategies from a technical viewpoint, plus a set of good practices and recommendations for upgrades management and governance. Notice how the value of the Box was preserved throughout the upgrade, as well as its address. Its worth mentioning that these restrictions have their roots in how the Ethereum VM works, and apply to all projects that work with upgradeable contracts, not just OpenZeppelin Upgrades. We pass a couple of parameters to the deployProxy. You may have noticed that we included a constructor as well as an initializer. Upgrades Plugins to deploy upgradeable contracts with automated security checks. JavaScript library for the OpenZeppelin smart contract platform Instead, we call the upgradeProxy function. After a period of time, we decide that we want to add functionality to our contract. Paste the following code into the file: After deploying the contract V1, we will be upgrading it to contract V2. Also, I see that the new vehicle for using OpenZeppelin is Truffle plugins. This is often the case, but not always, and that is where the need for upgradeable smart contracts arises. A survey of upgrade patterns, and good practices and recommendations for upgrades management and governance. Storage gaps are a convention for reserving storage slots in a base contract, allowing future versions of that contract to use up those slots without affecting the storage layout of child contracts. One hard rule about developing on the blockchain is that any smart contracts that are deployed cannot be altered. Lets pause and find out. In the three contract addresses that you opened, click on the contract tab on each of their pages. Due to a requirement of the proxy-based upgradeability system, no constructors can be used in upgradeable contracts. For the avoidance of doubt, this is separate from the version of OpenZeppelin Contracts that you use in your implementation contract. We only need Create Admin proposals and contracts capabilities, so select this and set an optional note to describe the key. We will name ours UpgradeableContracts, but you can call it anything you like. Instead, make sure to use @openzeppelin/contracts-upgradeable, which is an official fork of OpenZeppelin Contracts that has been modified to use initializers instead of constructors. Transfer control of upgrades (ownership of the ProxyAdmin) to a multisig. It is very important to work with this file carefully. Installation Done! We cannot make arbitrary changes to our contract, see, To test our upgrade we should create unit tests for the new implementation contract, along with creating higher level tests for testing interaction via the proxy, checking that state is maintained across upgrades. So, create Atm.sol. If you wish to test, your test file should be similar to this. OpenZeppelin Hardhat Upgrades API Both deployProxy and upgradeProxy functions will return instances of ethers.js contracts, and require ethers.js contract factories as arguments. Feel free to use the original terminal window youve initialized your project in. An attacker who gets hold of your upgrade admin account can change any upgradeable contract in your project! For example, deployProxy does the following: Validate that the implementation is upgrade safe. Before we upgrade our contract, remember to paste your proxy contract address (e.g, TransparentUpgradeableProxy address) in the variable UPGRADEABLE_PROXY above. It should look similar to this. Create scripts/upgrade-atmV2.js. As explained before, the state of the implementation contract is meaningless, as it does not change. You will also need to have a few Mumbai Testnet MATIC in your account to deploy your contracts. Upgradeable contracts cannot have a constructor. Learning new technology trends,applying them to solve problems is fascinating to me. Hardhat users will be able to write scripts that use the plugin to deploy or upgrade a contract, and manage proxy admin rights. This means that if the caller is not an admin, the proxy contract will not even consider executing any sort of upgrade function. Confirm that you are in the project directory (e.g, UpgradeableContracts) and then run this command in your terminal: If you did everything correctly, the terminal should tell you that it has compiled two solidity files successfully. My old environment consisted of using Truffle for development along with the zos-cli environment and Basil. You can use your Solidity contracts with OpenZeppelin Upgrades without any modifications, except for their constructors. However, for some scenarios, it is desirable to be able to modify them. You just deployed a smart contract to the Polygon Mumbai Testnet using Openzeppelins Transparent Upgradeable proxy. We need to specify the address of our proxy contract from when we deployed our Box contract. How do I get the latest 3.4.0 version of OpenZeppelin running on my PC? This variant is available as a separate package called @openzeppelin/contracts-upgradeable, which is hosted in the repository OpenZeppelin/openzeppelin-contracts-upgradeable. We are getting closer to that Solidity 1.0 release (unless of course after 0.9 comes 0.10). OpenZeppelin Upgradeable Contracts use the proxy pattern for upgradeability. Go into the contracts folder, and delete the pre-existing Greeter.sol file. Since these are internal, you must always define your own public initializer function and call the parent initializer of the contract you extend. If you want to use the Upgrades Plugins for an existing OpenZeppelin CLI project, you can migrate using the guide. Hardhat doesnt currently have a native deployment system, instead we use scripts to deploy contracts. Give yourselves a pat on the back. Now, run the following command in your terminal to start Hardhat: If everything is installed correctly, your terminal will look like this: Congratulations! Upgrades Plugins to deploy upgradeable contracts with automated security checks. To confirm everything runs correctly, save all your files and compile the contracts once more by running the command: If you followed all the steps correctly, Hardhat will compile your contracts again and give you a confirmation message. This means that if you have an initial contract that looks like this: Then you cannot change the type of a variable: Or change the order in which they are declared: Or introduce a new variable before existing ones: If you need to introduce a new variable, make sure you always do so at the end: Keep in mind that if you rename a variable, then it will keep the same value as before after upgrading. * {ERC1967Proxy}, when this contract is set as the implementation behind such a proxy. !Important: In order to be able to upgrade the Atm contract, we need to first deploy it as an upgradeable contract. Now that we have a blank canvas to work on, let us get down to painting it. Lets deploy our newly added contract with additional feature, we use the run command and deploy the AtmV2 contract to dev network. When you create a new upgradeable contract instance, the OpenZeppelin Upgrades Plugins actually deploys three contracts: The contract you have written, which is known as the implementation contract containing the logic. I was thinking about transferOwnership() to be included in the Migrations.sol so the ownership can be transferred to the Gnosis Safe.. After the transaction is successful, check out the value of number again. Transparent proxies include the upgrade and admin logic in the proxy itself. Deployment consists of implementation contract, ProxyAdmin and the proxy contract using OpenZeppelin Upgrades Plugins for Hardhat with a developer controlled private key. To propose the upgrade we use the Defender plugin for Hardhat. Defender Admin to manage upgrades in production and automate operations. We will save this file as scripts/deploy_upgradeable_box.js. Create transfer-ownership.js in the scripts directory with the following JavaScript. To create a storage gap, declare a fixed-size array in the base contract with an initial number of slots. Initializer functions are not linearized by the compiler like constructors. Truffle Tests (in javascript, with Web3.js, Moralis.io and other test helper libraries). (After a period of time) Create a new version of our implementation. In order to create Defender Admin proposals via the API we need a Team API key. There is, however, an exception. This will validate that the implementation is upgrade safe, deploy our new implementation contract and propose an upgrade. Events. To get started, youll need the following: A Defender account. 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