rookiecol / functions-chainlink

Smart contract calling an off chain API

Chainlink Constellation Hackathon, Fall 2023 - Demonstrating the Power of Chainlink Functions

This workshop demonstrates Chainlink Functions. The key dependency used is the Chainlink Functions Toolkit NPM Package

In this workshop, we will make an on-chain prompt to the OpenAPI ChatGPT API and get a decentralized response delivered back on chain -- all done via a single Smart Contract and some custom JavaScript that we supply that is executed by the Chainlink Decentralized Oracle Network!

The custom JS code that makes HTTP requests can receive dynamic arguments (the prompt we want answered) and access encrypted API keys (a.k.a secrets) to access the OpenAI API.

The source code that will be executed by Chainlink Functions is in ./source.js. This is the code that gets sent on-chain and then onto the Chainlink Decentralized Oracle Network for decentralized execution.

Prerequisites

1. Metamask funded with LINK tokens - fund here.. Also ensure you have enough test Mumbai Matic or Sepolia Eth. Network-specific configs are in ./networks.js but we set the NETWORK variable each of the files in ./scripts so that you can choose which one you want to use.

2. Install NPM and Node > v 17. If you wish to simulate the execution of your Chainlink Functions Locally using the in-built simulator (done in the ./scripts/simulateScript.ts script) you will also need to install Deno.

3. The following environment variables should be readily available (check the networks.js file to see which ones you will need and what name they are given):

The following ENV VARIABLE values
GPT_API_KEY --> get from https://platform.openai.com and then https://platform.openai.com/account/api-keys.
PRIVATE_KEY --> Wallet private key

POLYGON_MUMBAI_RPC_URL
## OR ##
ETHEREUM_SEPOLIA_RPC_URL

Set your environment variables using the env-enc package included.

1. Set password with npx env-enc set-pw. Remember this password otherwise you will have to set the env vars each time!
2. Set the above-mentioned env vars with npx env-enc set...and then follow the prompts.
3. After you set all the env vars, you can view the decrypted, human-readable version by running npx env-enc view

Note each time you open a fresh terminal or restart a terminal session you will need to run npx env-enc set-pw but not the other steps.

Steps

1. Go to the Functions Subscriptions App. This is the subscription management UI for functions. Connect your wallet to Polygon Mumbai/Sepolia on the Functions web app.

   Create your first subscription. This include two transactions:
       - one to accept the Terms of Service that adds your wallet address to the Allowlist, and
       - the other to create your Functions Subscription on-chain.
   
   Take a note of your Subscription Id as you will need it when using Chainlink Functions programmatically.
   
   Once a Functions Subscription is created you can manage it from the UI.
   

   
   

2. Please add at least 3 LINK to your subscription to run this project's code. This can be done from the ACTIONS button when your wallet is connected.
   

3. Follow along on the workshop!

Disclaimer

This tutorial offers educational examples of how to use a Chainlink system, product, or service and is provided to demonstrate how to interact with Chainlink’s systems, products, and services to integrate them into your own. This template is provided “AS IS” and “AS AVAILABLE” without warranties of any kind, it has not been audited, and it may be missing key checks or error handling to make the usage of the system, product, or service more clear. Do not use the code in this example in a production environment without completing your own audits and application of best practices. Neither Chainlink Labs, the Chainlink Foundation, nor Chainlink node operators are responsible for unintended outputs that are generated due to errors in code.