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πŸ—οΈŽ Scaffold Balancer v3

A starter kit for building on top of Balancer v3. Accelerate the process of creating custom pools and hooks contracts. Concentrate on mastering the core concepts within a swift and responsive environment augmented by a local fork and a frontend pool operations playground.

intro-to-scaffold-balancer

πŸ” Development Life Cycle

  1. Learn the core concepts for building on top of Balancer v3
  2. Configure and deploy factories, pools, and hooks contracts to a local anvil fork of Sepolia
  3. Interact with pools via a frontend that runs at localhost:3000

πŸͺ§ Table Of Contents

πŸ§‘β€πŸ’» Environment Setup

1. Requirements πŸ“œ

2. Quickstart πŸƒ

  1. Ensure you have the latest version of foundry installed
foundryup
  1. Clone this repo & install dependencies
git clone https://github.com/balancer/scaffold-balancer-v3.git
cd scaffold-balancer-v3
yarn install
  1. Set a SEPOLIA_RPC_URL in the packages/foundry/.env file
SEPOLIA_RPC_URL=...
  1. Start a local anvil fork of the Sepolia testnet
yarn fork
  1. Deploy the mock tokens, pool factories, pool hooks, and custom pools contracts

    By default, the anvil account #0 will be the deployer and recieve the mock tokens and BPT from pool initialization

yarn deploy
  1. Start the nextjs frontend
yarn start
  1. Explore the frontend
  1. Run the Foundry tests
yarn test

3. Scaffold ETH 2 Tips πŸ—οΈ

SE-2 offers a variety of configuration options for connecting an account, choosing networks, and deploying contracts

πŸ”₯ Burner Wallet

If you do not have an active wallet extension connected to your web browser, then scaffold eth will automatically connect to a "burner wallet" that is randomly generated on the frontend and saved to the browser's local storage. When using the burner wallet, transactions will be instantly signed, which is convenient for quick iterative development.

To force the use of burner wallet, disable your browsers wallet extensions and refresh the page. Note that the burner wallet comes with 0 ETH to pay for gas so you will need to click the faucet button in top right corner. Also the mock tokens for the pool are minted to your deployer account set in .env so you will want to navigate to the "Debug Contracts" page to mint your burner wallet some mock tokens to use with the pool.

Burner Wallet

Debug Tab Mint

πŸ‘› Browser Extension Wallet
  • To use your preferred browser extension wallet, ensure that the account you are using matches the PK you previously provided in the foundry/.env file
  • You may need to add a local development network with rpc url http://127.0.0.1:8545/ and chain id 31337. Also, you may need to reset the nonce data for your wallet exension if it gets out of sync.
πŸ› Debug Contracts Page

The Debug Contracts Page can be useful for viewing and interacting with all of the externally avaiable read and write functions of a contract. The page will automatically hot reload with contracts that are deployed via the 01_DeployConstantSumFactory.s.sol script. We use this handy setup to mint mockERC20 tokens to any connected wallet

🌐 Changing The Frontend Network Connection
  • The network the frontend points at is set via targetNetworks in the scaffold.config.ts file using chains from viem.
  • By default, the frontend runs on a local node at http://127.0.0.1:8545
const scaffoldConfig = {
  targetNetworks: [chains.foundry],
🍴 Changing The Forked Network
  • By default, the yarn fork command points at sepolia, but any of the network aliases from the [rpc_endpoints] of foundry.toml can be used to modify the "fork" alias in the packages/foundry/package.json file
	"fork": "anvil --fork-url ${0:-sepolia} --chain-id 31337 --config-out localhost.json",
  • To point the frontend at a different forked network, change the targetFork in scaffold.config.ts
const scaffoldConfig = {
  // The networks the frontend can connect to
  targetNetworks: [chains.foundry],

  // If using chains.foundry as your targetNetwork, you must specify a network to fork
  targetFork: chains.sepolia,

πŸ‘©β€πŸ« Learn Core Concepts

v3-components

πŸ•΅οΈ Explore the Examples

Each of the following examples have turn key deploy scripts that can be found in the foundry/script/ directory

1. Constant Sum Pool with Dynamic Swap Fee Hook

The swap fee percentage is altered by the hook contract before the pool calculates the amount for the swap

dynamic-fee-hook

2. Constant Product Pool with Lottery Hook

An after swap hook makes a request to an oracle contract for a random number

after-swap-hook

3. Weighted Pool with Exit Fee Hook

An after remove liquidity hook adjusts the amounts before the vault transfers tokens to the user

after-remove-liquidity-hook

🌊 Create a Custom Pool

custom-amm-video

1. Review the Docs πŸ“–

2. Recall the Key Requirements πŸ”‘

  • Must inherit from IBasePool and BalancerPoolToken
  • Must implement onSwap, computeInvariant, and computeBalance
  • Must implement getMaximumSwapFeePercentage and getMinimumSwapFeePercentage

3. Write a Custom Pool Contract πŸ“

  • To get started, edit theConstantSumPool.sol contract directly or make a copy

🏭 Create a Pool Factory

After designing a pool contract, the next step is to prepare a factory contract because Balancer's off-chain infrastructure uses the factory address as a means to identify the type of pool, which is important for integration into the UI, SDK, and external aggregators

1. Review the Docs πŸ“–

2. Recall the Key Requirements πŸ”‘

  • A pool factory contract must inherit from BasePoolFactory
  • Use the internal _create function to deploy a new pool
  • Use the internal _registerPoolWithVault fuction to register a pool immediately after creation

3. Write a Factory Contract πŸ“

  • To get started, edit theConstantSumFactory.sol contract directly or make a copy

πŸͺ Create a Pool Hook

hook-video

1. Review the Docs πŸ“–

2. Recall the Key Requirements πŸ”‘

  • A hooks contract must inherit from BasePoolHooks.sol
  • A hooks contract should also inherit from VaultGuard.sol
  • Must implement onRegister to determine if a pool is allowed to use the hook contract
  • Must implement getHookFlags to define which hooks are supported
  • The onlyVault modifier should be applied to all hooks functions (i.e. onRegister, onBeforeSwap, onAfterSwap ect.)

3. Write a Hook Contract πŸ“

  • To get started, edit the VeBALFeeDiscountHook.sol contract directly or make a copy

🚒 Deploy the Contracts

The deploy scripts are located in the foundry/script/ directory. To better understand the lifecycle of deploying a pool that uses a hooks contract, see the diagram below

pool-deploy-scripts

1. Modifying the Deploy Scripts πŸ› οΈ

For all the scaffold integrations to work properly, each deploy script must be imported into Deploy.s.sol and inherited by the DeployScript contract in Deploy.s.sol

2. Broadcast the Transactions πŸ“‘

Deploy to local fork

  1. Run the following command
yarn deploy

Deploy to a live network

  1. Add a DEPLOYER_PRIVATE_KEY to the packages/foundry/.env file
DEPLOYER_PRIVATE_KEY=0x...
SEPOLIA_RPC_URL=...

The DEPLOYER_PRIVATE_KEY must start with 0x and must hold enough Sepolia ETH to deploy the contracts. This account will receive the BPT from pool initialization

  1. Run the following command
yarn deploy --network sepolia

πŸ§ͺ Test the Contracts

The balancer-v3-monorepo provides testing utility contracts like BasePoolTest and BaseVaultTest. Therefore, the best way to begin writing tests for custom factories, pools, and hooks contracts is to leverage the examples established by the source code.

1. Testing Factories πŸ‘¨β€πŸ”¬

The ConstantSumFactoryTest roughly mirrors the WeightedPool8020FactoryTest

yarn test --match-contract ConstantSumFactoryTest

2. Testing Pools 🏊

The ConstantSumPoolTest roughly mirrors the WeightedPoolTest

yarn test --match-contract ConstantSumPoolTest

3. Testing Hooks 🎣

The VeBALFeeDiscountHookExampleTest mirrors the VeBALFeeDiscountHookExampleTest

yarn test --match-contract VeBALFeeDiscountHookExampleTest

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Starter kit for creating custom pools and hooks contracts on Balancer v3

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