index.js Implementation

The file index.js that is found in the top-level directory of your unique ID is the main entry point of your lambda function. This file should contain the majority of your JavaScript logic.

Mandatory exports

The file must export in CommonJs format the function register which registers the execution triggers that the lambda function is listening on.

module.exports.register = function(engine) {
  // register all triggers here
}

Importing dependencies

The file may import additional .js and .json dependencies that must be found in the same directory as the file index.js itself (or under a subdirectory next to it).

Importing must use the CommonJs require() syntax.

NPM packages may also be imported, subject to being in the allowed list.

const { ContractAbi } = require("./abi.js");

const Config = require("./config.json");

const BigNumber = require("bignumber.js");

Async await

Asynchronous code can and should use the modern async await syntax directly.

async function doSomething(web3) {
  const contract = new web3.eth.Contract(abi, address);
  const res = await contract.methods.readState();
}

Complete example

The following example monitors an Aave borrowing position every 10 minutes and if the position is close to liquidation, closes it using a contract that was deployed in advance for this lambda.

const BigNumber = require("bignumber.js");

// config
const aaveAbi = [{/* ... */}];
const closingAbi = [{/* ... */}];
const positionAddress = "0xe93C0f419AF19297D320563214Adbb2f28EF4C0c";

// globals
let aaveContract; // the standard Aave contract
let closingContract; // contract for closing Aave positions, deployed for this lambda

async function checkAavePosition(args) {
  if (!aaveContract) aaveContract = new args.web3.eth.Contract(aaveAbi, "0x7d2768dE32b0b80b7a3454c06BdAc94A69DDc7A9");
  if (!closingContract) closingContract = new args.web3.eth.Contract(aaveAbi, "0xBB51bD166d68c3DC5860190844Dfe1056Cea3122");
  const position = await aaveContract.methods.getPositionData(positionAddress).call();
  if (new BigNumber(position.healthFactor).dividedBy("1e18").toNumber() < 1.05) {
    await closingContract.methods.closePosition(positionAddress).send();
  }
}

module.exports.register = function(engine) {
  engine.onInterval(checkAavePosition, {
    interval: "10m", 
    network: "ethereum"
  });
}