Permissionless Chainlink Feeds

Powered by Hyperlane, easily bring any Chainlink price feed to your EVM compatible blockchain.

How does it work?

By deploying a slightly simplified version of the Chainlink OffchainAggregator, we can replay transactions from any chain Chainlink operates on to your chain. Crucially, and what makes this useful, is we only need to rely on the security of Chainlink oracles themselves to secure these updates.

A full diff of the changes to the OffchainAggregator used for this integration and the official ones deployed by Chainlink can be found by running the following from the root of the repository.

git diff --no-index ./apps/contracts/chainlink-ocr-original/ ./apps/contracts/contracts/chainlink-ocr/

Deployment

A convenient frontend for deploying a Chainlink feed to your chain can be found here. If you'd prefer to run commands yourself or are deploying to a chain that only recently had Hyperlane deployed to it, the following guide will help you get up and running.

This guide assumes we'll be deploying the ETH/USD feed from Goerli to Mumbai, but feel free to alter these variables as you see fit (here).

We'll first get your dependencies installed by running,

➜  pnpm install

API

The API handles querying Chainlink specific data either from the chain itself or via an indexing provider like Etherscan or Moralis.

First, setup your environment variables,

➜  cd apps/frontend
➜  cd .env.example .env

And then run the service,

➜  pnpm dev

If you'd prefer to not run this service, you can rely on an already live one at https://permissionless-chainlink-feeds-frontend.vercel.app/api. Just make sure to replace the API_ENDPOINT variable in apps/contracts/scripts/utils.ts with this live URL.

Smart contracts

Again we need to first we need to setup our environment variables,

➜  cd app/contracts
➜  cp .env.example .env

Then we can deploy the ChainlinkAggregator. This script will query initialisation variables from the API server you ran in the previous step, so make sure you've got that running before deploying this.

➜  pnpm hardhat run ./scripts/deploy-aggregator.ts --network mumbai

To test everything is working, we can manually relay the latest round data from Goerli to Mumbai,

➜  pnpm hardhat run ./scripts/update-answer.ts --network goerli

And finally query the latest round data on Mumbai,

➜  pnpm hardhat run ./scripts/get-answer.ts --network mumbai
[
  BigNumber { value: "1" },
  BigNumber { value: "188363730000" },
  BigNumber { value: "1687787078" },
  BigNumber { value: "1687787078" },
  BigNumber { value: "1" },
  roundId: BigNumber { value: "1" },
  answer: BigNumber { value: "188363730000" },
  startedAt: BigNumber { value: "1687787078" },
  updatedAt: BigNumber { value: "1687787078" },
  answeredInRound: BigNumber { value: "1" }
]

Automation

Triggering round updates manually as we've just done is great, but even better would be some kind of automated process to relay new round data as soon as its submitted on chain. There are of course many options available to us to automate these round updates, a few ideas that spring to mind include,

• Running a lightweight indexer that upon finding NewTransmission events, sends the origin chain message
• Setup a CRON job that queries for the latest round ID and upon finding a new one, sends the origin chain message
• Configure an onchain messaging system like Gelato or Keeper to periodically post the round data.

Configuring Gelato is one of the simplest ways to get started with on chain automation and they support many of the same networks that Hyperlane does. Running the following command,

➜  pnpm hardhat run ./scripts/deploy-gelato.ts --network goerli

Will deploy an instance of the GelatoAutomate contract and fund it with 1 GoerliETH. There will also be additional logging similar to this,

[gelato] deploying...
[gelato] deployed to: 0xF19C411808288e78Bb7C7DeC2b782217B0666838
[gelato] funded for interchain gas payments
Creating Task...
Task created, taskId: 0x630181458d62d420bfde1303320f15e931c7fbf0f4e26b3da42c8e9a01e4667a (tx hash: 0xe43fa116ac1e471d893d0f6ed1a57daef5854d8ddf18015855f4db344e1e627a)
> https://app.gelato.network/task/0x630181458d62d420bfde1303320f15e931c7fbf0f4e26b3da42c8e9a01e4667a?chainId=5

So you can navigate to the Gelato dashboard and monitor the automations status yourself.