World
Upgrading

Upgrading worlds

The Systems can be upgraded without changing the underlying World code. However, if the World was deployed behind a proxy it is also possible to upgrade the World itself. This allows you to upgrade to a future version of MUD, but adds some gas overhead for all calls (due to one more level of indirection).

Are upgrades possible?

As per ERC-1967 (opens in a new tab), the storage slot 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc stores the address of the World implementation in a proxy. So to identify if a World is deployed behind a proxy run these commands:

WORLD_ADDRESS=0xbe6b85dc88f969e45d8d8ae128c5a9c9744d6464
cast implementation $WORLD_ADDRESS

If the answer is anything other than zero, the World is behind a proxy and can be upgraded.

Performing an upgrade

To upgrade the World use these steps in a package/contracts directory:

  1. Edit .env to add WORLD_ADDRESS with the address displayed by MUD Dev Tools. For example, you might want to use this file:

    .env
    # This .env file is for demonstration purposes only.
#
# This should usually be excluded via .gitignore and the env vars attached to
# your deployment environment, but we're including this here for ease of local
# development. Please do not commit changes to this file!
#
# Enable debug logs for MUD CLI
DEBUG=mud:*
#
# Anvil default private key:
PRIVATE_KEY=0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80
WORLD_ADDRESS=0xbe6b85dc88f969e45d8d8ae128c5a9c9744d6464

  2. Create this script in scripts/UpgradeWorld.s.sol.

    UpgradeWorld.s.sol
    // SPDX-License-Identifier: MIT
pragma solidity >=0.8.24;
 
import { Script } from "forge-std/Script.sol";
import { console } from "forge-std/console.sol";
 
import { World } from "@latticexyz/world/src/World.sol";
import { WorldProxy } from "@latticexyz/world/src/WorldProxy.sol";
 
contract SetImplementation is Script {
  function run() external {
    uint256 deployerPrivateKey = vm.envUint("PRIVATE_KEY");
    vm.startBroadcast(deployerPrivateKey);
 
    address proxyAddress = vm.envAddress("WORLD_ADDRESS");
 
    // Deploy new world implementation
    World newWorld = new World();
 
    console.log("proxy:", proxyAddress);
    console.log("new World:", address(newWorld));
 
    WorldProxy(payable(proxyAddress)).setImplementation(address(newWorld));
 
    vm.stopBroadcast();
  }
}

  3. Run the script.

    forge script script/UpgradeWorld.s.sol --rpc-url http://localhost:8545 --broadcast

  4. See the new address.

    source .env
cast implementation $WORLD_ADDRESS
Batch CallsModules