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https://github.com/udaysingh131105/raffle-lottery-smartcontract-vrf-v2_5

This Raffle Contract helps us to implement the ChainLink VRF and ChainLink Keepers to pick random players as the winners for the lottery
https://github.com/udaysingh131105/raffle-lottery-smartcontract-vrf-v2_5

block blockchain chainlink chainlink-keepers chainlink-vrf ethereum hardhat sepolia sepoliatestnetwork smart-contracts solidity

Last synced: 14 days ago
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This Raffle Contract helps us to implement the ChainLink VRF and ChainLink Keepers to pick random players as the winners for the lottery

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README 

        
# Hardhat Smartcontract Lottery (Raffle)



This project was created by Uday Singh and this contract is for creating an untamperable decentralized smart contract where users can deposit a minimum amount of ETH and win more back in a fair winning play.



# Getting Started



## Requirements



- [git](https://git-scm.com/book/en/v2/Getting-Started-Installing-Git)

  - You'll know you did it right if you can run `git --version` and you see a response like `git version x.x.x`

- [Nodejs](https://nodejs.org/en/)

  - You'll know you've installed nodejs right if you can run:

    - `node --version` and get an ouput like: `vx.x.x`

- [Yarn](https://yarnpkg.com/getting-started/install) instead of `npm`

  - You'll know you've installed yarn right if you can run:

    - `yarn --version` and get an output like: `x.x.x`

    - You might need to [install it with `npm`](https://classic.yarnpkg.com/lang/en/docs/install/) or `corepack`



## Quickstart



```

git clone https://github.com/UdaySingh131105/Raffle-Lottery-SmartContract-VRF-V2_5.git

cd Raffle-Lottery-SmartContract-VRF-V2_5

yarn

```



# Usage



Deploy:



```

yarn hardhat deploy

```



## Testing



```

yarn hardhat test

```



### Test Coverage



```

yarn hardhat coverage

```



# Deployment to a testnet or mainnet



1. Setup environment variabltes



You'll want to set your `SEPOLIA_RPC_URL` and `PRIVATE_KEY` as environment variables. You can add them to a `.env` file, similar to what you see in `.env.example`.



- `PRIVATE_KEY`: The private key of your account (like from [metamask](https://metamask.io/)). **NOTE:** FOR DEVELOPMENT, PLEASE USE A KEY THAT DOESN'T HAVE ANY REAL FUNDS ASSOCIATED WITH IT.

  - You can [learn how to export it here](https://metamask.zendesk.com/hc/en-us/articles/360015289632-How-to-Export-an-Account-Private-Key).

- `SEPOLIA_RPC_URL`: This is url of the sepolia testnet node you're working with. You can get setup with one for free from [Alchemy](https://alchemy.com/?a=673c802981)



2. Get testnet ETH



Head over to [faucets.chain.link](https://faucets.chain.link/) and get some tesnet ETH & LINK. You should see the ETH and LINK show up in your metamask. [You can read more on setting up your wallet with LINK.](https://docs.chain.link/docs/deploy-your-first-contract/#install-and-fund-your-metamask-wallet)



3. Setup a Chainlink VRF Subscription ID



Head over to [vrf.chain.link](https://vrf.chain.link/) and setup a new subscription, and get a subscriptionId. You can reuse an old subscription if you already have one. 



[You can follow the instructions](https://docs.chain.link/docs/get-a-random-number/) if you get lost. You should leave this step with:



1. A subscription ID

2. Your subscription should be funded with LINK



3. Deploy



In your `helper-hardhat-config.js` add your `subscriptionId` under the section of the chainId you're using (aka, if you're deploying to sepolia, add your `subscriptionId` in the `subscriptionId` field under the `11155111` section.)



Then run:

```

yarn hardhat deploy --network sepolia

```



And copy / remember the contract address. 



4. Add your contract address as a Chainlink VRF Consumer



Go back to [vrf.chain.link](https://vrf.chain.link) and under your subscription add `Add consumer` and add your contract address. You should also fund the contract with a minimum of 1 LINK. 



5. Register a Chainlink Keepers Upkeep



[You can follow the documentation if you get lost.](https://docs.chain.link/docs/chainlink-keepers/compatible-contracts/)



Go to [keepers.chain.link](https://keepers.chain.link/new) and register a new upkeep. Choose `Custom logic` as your trigger mechanism for automation. Your UI will look something like this once completed:



![Keepers](./img/keepers.png)



6. Enter your raffle!



You're contract is now setup to be a tamper proof autonomous verifiably random lottery. Enter the lottery by running:



```

yarn hardhat run scripts/enter.js --network sepolia

```



### Estimate gas cost in USD



To get a USD estimation of gas cost, you'll need a `COINMARKETCAP_API_KEY` environment variable. You can get one for free from [CoinMarketCap](https://pro.coinmarketcap.com/signup). 



Then, uncomment the line `coinmarketcap: COINMARKETCAP_API_KEY,` in `hardhat.config.js` to get the USD estimation. Just note, everytime you run your tests it will use an API call, so it might make sense to have using coinmarketcap disabled until you need it. You can disable it by just commenting the line back out. 



## Verify on etherscan



If you deploy to a testnet or mainnet, you can verify it if you get an [API Key](https://etherscan.io/myapikey) from Etherscan and set it as an environemnt variable named `ETHERSCAN_API_KEY`. You can pop it into your `.env` file as seen in the `.env.example`.



In it's current state, if you have your api key set, it will auto verify sepolia contracts!



However, you can manual verify with:



```

yarn hardhat verify --constructor-args arguments.js DEPLOYED_CONTRACT_ADDRESS

```



# Linting



To check linting / code formatting:

```

yarn lint

```

or, to fix: 

```

yarn lint:fix

```



# Thank you!