Relayer

The relayer is the middle man connecting the smart contracts to the PDC canister, it is powered by gelato functions. The relayer mechanism serves as an indexer which queries events from the blockchain and publishes it to a logstore stream which via https. Logstore serves as a time series database, that can then be queried by the PDC via http to get the latest events published by the locker smart contract.

Running the relayer

The relayer can be run locally by running the command npm run run-relayer:goerli

Deploying the relayer

The relayer can be deployed by running npm run deploy-relayer

More on Web3 Function

Use this template to write, test and deploy Web3 Functions.

What are Web3 Functions?

Web3 Functions are decentralized cloud functions that work similarly to AWS Lambda or Google Cloud, just for web3. They enable developers to execute on-chain transactions based on arbitrary off-chain data (APIs / subgraphs, etc) & computation. These functions are written in Typescript, stored on IPFS and run by Gelato.

Documentation

You can find the official Web3 Functions documentation here.

Private Beta Restriction

Web3 Functions are currently in private Beta and can only be used by whitelisted users. If you would like to be added to the waitlist, please reach out to the team on Discord or apply using this form.

Table of Content

• Relayer
  • Running the relayer
  • Deploying the relayer
  • What are Web3 Functions?
  • Documentation
  • Private Beta Restriction
  • Table of Content
  • Project Setup
  • Hardhat Config
  • Write a Web3 Function
  • Test your web3 function
    • Calling your web3 function

Project Setup

1. Install project dependencies

yarn install

2. Configure your local environment:

• Copy .env.example to init your own .env file

cp .env.example .env

• Complete your .env file with your private settings

ALCHEMY_ID=
PRIVATE_KEY=

Hardhat Config

In hardhat.config.ts, you can set up configurations for your Web3 Function runtime.

• rootDir: Directory which contains all web3 functions directories.
• debug: Run your web3 functions with debug mode on.
• networks: Provider of these networks will be injected into web3 function's multi chain provider.

  w3f: {
    rootDir: "./web3-functions",
    debug: false,
    networks: ["mumbai", "goerli", "baseGoerli"],
  },

Write a Web3 Function

• Go to web3-functions/index.ts
• Write your Web3 Function logic within the Web3Function.onRun function.
• Example:

import {
  Web3Function,
  Web3FunctionContext,
} from "@gelatonetwork/web3-functions-sdk";
import { Contract } from "@ethersproject/contracts";
import ky from "ky"; // we recommend using ky as axios doesn't support fetch by default

const ORACLE_ABI = [
  "function lastUpdated() external view returns(uint256)",
  "function updatePrice(uint256)",
];

Web3Function.onRun(async (context: Web3FunctionContext) => {
  const { userArgs, gelatoArgs, multiChainProvider } = context;

  const provider = multiChainProvider.default();

  // Retrieve Last oracle update time
  const oracleAddress = "0x71B9B0F6C999CBbB0FeF9c92B80D54e4973214da";
  const oracle = new Contract(oracleAddress, ORACLE_ABI, provider);
  const lastUpdated = parseInt(await oracle.lastUpdated());
  console.log(`Last oracle update: ${lastUpdated}`);

  // Check if it's ready for a new update
  const nextUpdateTime = lastUpdated + 300; // 5 min
  const timestamp = (await provider.getBlock("latest")).timestamp;
  console.log(`Next oracle update: ${nextUpdateTime}`);
  if (timestamp < nextUpdateTime) {
    return { canExec: false, message: `Time not elapsed` };
  }

  // Get current price on coingecko
  const currency = "ethereum";
  const priceData: any = await ky
    .get(
      `https://api.coingecko.com/api/v3/simple/price?ids=${currency}&vs_currencies=usd`,
      { timeout: 5_000, retry: 0 }
    )
    .json();
  price = Math.floor(priceData[currency].usd);
  console.log(`Updating price: ${price}`);

  // Return execution call data
  return {
    canExec: true,
    callData: [{to: oracleAddress, data: oracle.interface.encodeFunctionData("updatePrice", [price])}],
  };
});

• Each Web3 Function has a schema.json file to specify the runtime configuration. In later versions you will have more optionality to define what resources your Web3 Function requires.

{
  "web3FunctionVersion": "2.0.0",
  "runtime": "js-1.0",
  "memory": 128,
  "timeout": 30,
  "userArgs": {}
}

Test your web3 function

Calling your web3 function

• Use npx hardhat w3f-run W3FNAME command to test your function (replace W3FNAME with the folder name containing your web3 function)

• Options:

  • --logs Show internal Web3 Function logs
  • --debug Show Runtime debug messages
  • --network [NETWORK] Set the default runtime network & provider.

If your web3 function has arguments, you can define them in hardhat.config.ts.

Example:
npx hardhat w3f-run oracle --logs

Output:

Web3Function building...

Web3Function Build result:
✓ Schema: web3-functions/examples/oracle/schema.json
✓ Built file: ./.tmp/index.js
✓ File size: 2.46mb
✓ Build time: 255.66ms

Web3Function user args validation:
✓ currency: ethereum
✓ oracle: 0x71B9B0F6C999CBbB0FeF9c92B80D54e4973214da

Web3Function running...

Web3Function Result:
✓ Return value: { canExec: false, message: 'Rpc call failed' }

Web3Function Runtime stats:
✓ Duration: 0.41s
✓ Memory: 65.65mb
✓ Rpc calls: 2