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Deploying Upgradeable Contracts using UUPS with Foundry

UUPS (Universal Upgradeable Proxy Standard)​

[Keep the same UUPS explanation section as in the original tutorial...]

Project Setup​

  1. Create a new Foundry project:
forge init uups-proxy-foundry-demo
cd uups-proxy-foundry-demo
  1. Install OpenZeppelin contracts:
forge install OpenZeppelin/openzeppelin-contracts
forge install OpenZeppelin/openzeppelin-contracts-upgradeable
  1. Configure Foundry

Update your foundry.toml:

[profile.default]
src = "src"
out = "out"
libs = ["lib"]
solc = "0.8.24"
remappings = [
    "@openzeppelin/contracts/=lib/openzeppelin-contracts/contracts/",
    "@openzeppelin/contracts-upgradeable/=lib/openzeppelin-contracts-upgradeable/contracts/"
]
  1. Create a .env file:
PRIVATE_KEY=your_private_key_here
RPC_URL=https://evmtestnet.confluxrpc.com

Writing Smart Contracts​

  1. Create the initial Counter contract in src/Counter.sol:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

import "@openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol";
import "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable/proxy/utils/UUPSUpgradeable.sol";

contract Counter is Initializable, OwnableUpgradeable, UUPSUpgradeable {
    uint256 public number;

    /// @custom:oz-upgrades-unsafe-allow constructor
    constructor() {
        _disableInitializers();
    }

    function initialize() public initializer {
        __Ownable_init(msg.sender);
        __UUPSUpgradeable_init();
        number = 0;
    }

    function setNumber(uint256 newNumber) public {
        number = newNumber;
    }

    function increment() public {
        number++;
    }

    function getCount() public view returns (uint256) {
        return number;
    }

    function _authorizeUpgrade(address newImplementation) internal override onlyOwner {}
}

  1. Create CounterV2 in src/CounterV2.sol:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

import "@openzeppelin/contracts-upgradeable/proxy/utils/UUPSUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";

contract CounterV2 is UUPSUpgradeable, OwnableUpgradeable {
    uint256 private count;

    event CountChanged(uint256 count);

    /// @custom:oz-upgrades-unsafe-allow constructor
    constructor() {
        _disableInitializers();
    }

    function initialize() public initializer {
        __Ownable_init(msg.sender);
        __UUPSUpgradeable_init();
    }

    function increment() public {
        count += 1;
        emit CountChanged(count);
    }

    function getCount() public view returns (uint256) {
        return count;
    }

    function reset() public {
        count = 0;
        emit CountChanged(count);
    }

    function _authorizeUpgrade(address newImplementation) internal override onlyOwner {}
}

Deployment Scripts​

  1. Create a deployment script in script/DeployCounter.s.sol:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

import "forge-std/Script.sol";
import "../src/Counter.sol";
import "@openzeppelin/contracts/proxy/ERC1967/ERC1967Proxy.sol";

contract DeployCounter is Script {
    function run() external {
        uint256 deployerPrivateKey = vm.envUint("PRIVATE_KEY");

        vm.startBroadcast(deployerPrivateKey);

        // Deploy implementation
        Counter counter = new Counter();
        console.log("Implementation deployed to:", address(counter));

        // Encode initialize function call
        bytes memory data = abi.encodeWithSelector(Counter.initialize.selector);

        // Deploy proxy
        ERC1967Proxy proxy = new ERC1967Proxy(
            address(counter),
            data
        );
        console.log("Proxy deployed to:", address(proxy));

        // Verify deployment
        Counter proxiedCounter = Counter(address(proxy));
        console.log("Initial count:", proxiedCounter.getCount());

        vm.stopBroadcast();
    }
}
  1. Create an upgrade script in script/UpgradeCounter.s.sol:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

import "forge-std/Script.sol";
import "../src/Counter.sol";
import "../src/CounterV2.sol";

contract UpgradeCounter is Script {
    function run() external {
        uint256 deployerPrivateKey = vm.envUint("PRIVATE_KEY");
        address proxyAddress = vm.envAddress("PROXY_ADDRESS");

        // Test before upgrade
        console.log("============ Before Upgrade ============");
        Counter counter = Counter(proxyAddress);
        uint256 valueBefore = counter.getCount();
        console.log("Current count:", valueBefore);

        vm.startBroadcast(deployerPrivateKey);

        // Deploy new implementation
        CounterV2 counterV2 = new CounterV2();
        console.log("\n============ Deploying New Implementation ============");
        console.log("New implementation:", address(counterV2));

        // Upgrade proxy to new implementation
        Counter(proxyAddress).upgradeToAndCall(
            address(counterV2),
            "" // Empty bytes string since we don't need to call any initialization function
        );

        vm.stopBroadcast();

        // Test after upgrade
        console.log("\n============ After Upgrade ============");
        CounterV2 upgradedCounter = CounterV2(proxyAddress);
        uint256 valueAfter = upgradedCounter.getCount();
        console.log("Count after upgrade:", valueAfter);

        vm.startBroadcast(deployerPrivateKey);
        upgradedCounter.increment();
        vm.stopBroadcast();

        uint256 valueAfterIncrement = upgradedCounter.getCount();
        console.log("Count after increment:", valueAfterIncrement);

        vm.startBroadcast(deployerPrivateKey);
        upgradedCounter.reset();
        vm.stopBroadcast();

        uint256 valueAfterReset = upgradedCounter.getCount();
        console.log("Count after reset:", valueAfterReset);

        // Verify upgrade results
        require(valueAfter == valueBefore, "State verification failed: Value changed during upgrade");
        require(valueAfterIncrement == valueAfter + 1, "Function verification failed: Increment not working");
        require(valueAfterReset == 0, "Function verification failed: Reset not working");

        console.log("\n============ Upgrade Successful ============");
        console.log("1. State preserved: Initial count maintained after upgrade");
        console.log("2. New functions working: Increment and Reset successfully added");
    }
}

Testing​

Create a test file in test/Counter.t.sol:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

import "forge-std/Test.sol";
import "../src/Counter.sol";
import "../src/CounterV2.sol";
import "@openzeppelin/contracts/proxy/ERC1967/ERC1967Proxy.sol";

contract CounterTest is Test {
    Counter public implementation;
    CounterV2 public implementationV2;
    ERC1967Proxy public proxy;
    address owner = address(this);

    function setUp() public {
        // Deploy implementation
        implementation = new Counter();
        
        // Encode initialize function call
        bytes memory data = abi.encodeWithSelector(Counter.initialize.selector);
        
        // Deploy proxy
        proxy = new ERC1967Proxy(
            address(implementation),
            data
        );
    }

    function testIncrement() public {
        Counter(address(proxy)).increment();
        assertEq(Counter(address(proxy)).getCount(), 1);
    }

    function testUpgrade() public {
        // Deploy new implementation
        implementationV2 = new CounterV2();
        
        // Upgrade
        Counter(address(proxy)).upgradeTo(address(implementationV2));
        
        // Test new functionality
        CounterV2(address(proxy)).increment();
        assertEq(CounterV2(address(proxy)).getCount(), 1);
        
        CounterV2(address(proxy)).reset();
        assertEq(CounterV2(address(proxy)).getCount(), 0);
    }
}

Deployment and Upgrade Process​

  1. Deploy the initial implementation and proxy:
source .env
forge script script/DeployCounter.s.sol --rpc-url $RPC_URL --broadcast -g 200

Note: The -g flag sets the gas price multiplier (in percentage). Using -g 200 means the gas price will be 200% of the estimated price, which helps prevent "insufficient gas fee" errors during deployment.

Expected output:

Deploying Counter...
Implementation deployed to: <IMPLEMENTATION_ADDRESS>
Proxy deployed to: <PROXY_ADDRESS>
Initial count: 0
  1. After deployment, save the proxy address in .env:
PROXY_ADDRESS=<PROXY_ADDRESS>
  1. Upgrade to CounterV2:
forge script script/UpgradeCounter.s.sol --rpc-url $RPC_URL --broadcast -g 200

Expected output:

============ Before Upgrade ============
Current count: 0

============ Deploying New Implementation ============
New implementation: <IMPLEMENTATION_V2_ADDRESS>

============ After Upgrade ============
Count after upgrade: 0
Count after increment: 1
Count after reset: 0

============ Upgrade Successful ============
1. State preserved: Initial count maintained after upgrade
2. New functions working: Increment and Reset successfully added

By following these steps, you can deploy and upgrade smart contracts using UUPS proxy pattern on Conflux eSpace with Foundry. This pattern provides a more gas-efficient alternative to the transparent proxy pattern while maintaining upgradeability. The UUPS pattern moves the upgrade logic to the implementation contract, making it more lightweight and cost-effective for users.