This use case showcases how Chainlink Functions can be used to facilitate a agreement between a project owner and a Key Opinion Leader (KOL), with Chainlink Functions being used to obtain the KOL's tweets.
The CommunityEngine contract represents an on-chain agreement and payment contract between a project owner and the KOL. Chainlink Functions is used to verify the KOL's tweets for the project based on the agreement signed, using Mainline's API. The KOL is paid in USDC. If the KOL fails to meet the agreement requirements, the USDC is then returned to the project owner.
The project owner and the KOL have an agreed payment amount. This payout is part of the smart contract's code and represents a trust-minimized, verifiable, on-chain record of the agreement. For example, the KOL will receive 100 USDC once they tweet using the agreed upon keywords.
If the KOL tweets out using the agreed upon keywords, the Chainlink Functions code will also send out a status showing that the KOL sent out those tweets back to the smart contract so it can be recorded immutably on the blockchain. The returned value is passed through Chainlink's Off-Chain Reporting consensus mechanism - which the nodes in the Decentralized Oracle Network (DON). Once that status is recorded, the KOL is then paid out in USDC or the USDC is returned back to the project owner, and the project is completed.
This project is currently in a closed beta. Request access to send on-chain requests here https://functions.chain.link/
- Node.js version 18
- Clone this repository to your local machine
- Open this directory in your command line, then run
npm installto install all dependencies. - Set the required environment variables.
- Set an encryption password for your environment variables to a secure password by running:
npx env-enc set-pw - Use the command
npx env-enc setto set the required environment variables (see Environment Variable Management):- ETHEREUM_SEPOLIA_RPC_URL for the Sepolia network RPC
- PRIVATE_KEY for your development wallet
- ETHERSCAN_API_KEY for verifying the deployed contracts on Etherscan
- MAINLINE_API_KEY for retrieving a KOL's tweets from a Chainlink Function using Mainline's API
- Set an encryption password for your environment variables to a secure password by running:
- There are two files to notice that the default example will use:
- contracts/app/CommunityEngine.sol contains the smart contract that will receive the data
- app.request.js contains JavaScript code that will be executed by each node of the DON
- Deploy and verify the client contract to an actual blockchain network by running:
npx hardhat functions-deploy-communityengine --network ethereumSepolia --verify true
Note: Make sureETHERSCAN_API_KEYis set if using--verify true. - Create, fund & authorize a new Functions billing subscription by running:
npx hardhat functions-sub-create --network ethereumSepolia --amount <LINK-funding-amount> --contract <deployed-contract-address>
Note: Ensure your wallet has a sufficient LINK balance before running this command. Testnet LINK can be obtained at faucets.chain.link. - Make an on-chain request by running:
npx hardhat functions-request --network ethereumSepolia --gaslimit 300000 --contract <deployed-contract-address> --subid <subscription-id>
This repo uses the NPM package @chainlink/env-enc for keeping environment variables such as wallet private keys, RPC URLs, and other secrets encrypted at rest. This reduces the risk of credential exposure by ensuring credentials are not visible in plaintext.
By default, all encrypted environment variables will be stored in a file named .env.enc in the root directory of this repo.
First, set the encryption password by running the command npx env-enc set-pw.
The password must be set at the beginning of each new session.
If this password is lost, there will be no way to recover the encrypted environment variables.
Run the command npx env-enc set to set and save environment variables.
These variables will be loaded into your environment when the config() method is called at the top of hardhat.config.js.
Use npx env-enc view to view all currently saved environment variables.
When pressing ENTER, the terminal will be cleared to prevent these values from remaining visible.
Running npx env-enc remove VAR_NAME_HERE deletes the specified environment variable.
The command npx env-enc remove-all deletes the entire saved environment variable file.
When running this command on a Windows machine, you may receive a security confirmation prompt. Enter r to proceed.
NOTE: When you finish each work session, close down your terminal to prevent your encryption password from becoming exposes if your machine is compromised.