Lottery contract with Chainlink VRFv2 and Automation. The contract is using Chainlink VRFv2 for generating random numbers and Chainlink Automation to pick a winner periodically.

Therefore, for the correct operation of the contract, it is necessary to:

• create subscription on > https://vrf.chain.link/sepolia for sepolia testnet, replenish the balance of LINK and add contract address as a consumer
• create time-based upkeep on > https://automation.chain.link/sepolia for sepolia testnet, replenish the balance of LINK, add contract address, specify target function and schedule to be triggered.

• General Info
• Technologies Used
• Features
• Requirements For Initial Setup
• Setup
• Contact

• The lottery is start right after the contract is deployed
• Every user can participate with 0.01 ETH
• After the scheduler (Upkeep) end a lottery round, the winner will be picked using randomness from Chainlink VRFv2 Coordinator
• Then, new lottery round start again

• Chainlink VRFv2
• Chainlink Automation
• solhint
• docgen
• hardhat-deploy
• trailofbits/eth-security-toolbox

• Trully random contract(Ideally for lottery)
• Fully autonomous contract without human intervention

• Install NodeJS, should work with any node version above 16.16.0
• Install Yarn, if yarn version >1.22.19 is installed, set it to version 1.22.19

  yarn set version 1.22.19

• Install Hardhat

$ cd eth-solidity-hardhat-lottery
$ yarn install

Create a .env file inside the project directory by making a copy of .env.sample file and filling in the required variables.

• You can get your ethereum or testnet URL here, here or any other service that allow you to connect to the nodes
• You can get your private key from your wallet (Don't share your private key with untrusted parties)
• Subscription id can be obtained here after creation of subscription here
• Gas Lane/Key Hash and address of vrf coordinator can be obtained from here here Just choose network and copy. :)
• You can get your etherscan API key here.
• You can get your coinmarketcap API key here if you want the gas cost reported in USD.

SEPOLIA_RPC_URL = <URL to connect to sepolia testnet>
PRIVATE_KEY = <Private key of your wallet u want to deploy contracts from, make sure it didn't has real money>
ETHERSCAN_API_KEY = <Etherscan API key in order to verify your contracts>
REPORT_GAS = <true or false to enabled or disabled gas reporting>
COINMARKETCAP_API_KEY = <Coinmarketcap API key in order to get the current price of ETH used by gas reporter>
VRF_COORDINATOR_V2 = <VRF coordinator address(depends on network)>
SUBSCRIPTION_ID = <VRFv2 subscription id.>
GAS_LANE = <Gas lane or key hash(depends on network)>
CALLBACK_GAS_LIMIT = <The gas limit to use for the VRFv2 callback function>
UPKEEP_PERFORM_IN_SECONDS = <Interval between lottery rounds>
LOTTERY_ENTRANCE_FEE = <Entrance fee of the lottery>

The .env.ci file is used by GitHub Actions (.github/workflows/hardhat.yml) to run unit test, display gas report and run code coverage on every git push and pull request.

$ yarn test

$ yarn coverage

$ yarn deploy:sepolia

01-deploy-lottery.ts implements the verification script and you don't need to complete any additional steps in order to verify the contract.

Created by @limcheekin - feel free to contact me!