Foundry Raffle

A decentralized raffle smart contract using Chainlink VRF for provably fair random winner selection and Chainlink Automation for automated execution

Overview

Automated lottery system that-

• Accepts entries via entrance fee
• Automatically selects random winner using Chainlink VRF
• Distributes entire contract balance to winner
• Uses Chainlink Keepers to trigger winner selection at intervals

States: OPEN (accepting entries) → CALCULATING (selecting winner)

Prerequisites

• Foundry
• For testnet/mainnet: Chainlink VRF subscription at vrf.chain.link, LINK tokens, and ETH

Contract Functions

Main Functions:

• enterRaffle() - Enter raffle (pay entrance fee)
• checkUpkeep() - Check if upkeep needed (Chainlink Keepers)
• performUpkeep() - Trigger VRF request
• fulfillRandomWords() - VRF callback (selects winner)

Getters: getRaffleState(), getRecentWinner(), getNumberOfPlayers(), getEntranceFee(), etc.

Events: RaffleEnter, RequestedRaffleWinner, WinnerPicked

Project Structure

src/Raffle.sol                 # Main contract
script/DeployRaffle.s.sol      # Deployment script
script/HelperConfig.s.sol      # Network config
test/unit/RaffleTest.t.sol     # Unit tests
test/integration/              # Integration tests

Documentation

• Foundry Book
• Chainlink VRF v2.5
• Chainlink Automation

License

MIT

Author

Ohburmaa