Chainlink Integration

This document explains how to consume Chainlink oracles when unit testing, integration testing, and actually on-chain.

Overview

Using Chainlink on Agoric provides two main features:

• Price feeds are exposed on Agoric via the on-chain home.priceAuthority. This is an officially-sponsored price authority built from aggregating several Chainlink nodes.
• Chainlink's Any API can initiate a job on a single oracle and return its results

We have tested these features with actual Chainlink oracle software.

Note: Chainlink has not yet (as of Nov 16, 2020) finished setting up an incentivized testnet for established Chainlink node operators to connect to Agoric.

Price Authority

To test your contract against a locally-simulated price authority, just follow the instructions in the Price Authority API.

To use the curated on-chain price authority, see home.priceAuthority. For example, to get a quote for selling 30 Testnet.$LINK in Testnet.$USD:

(Note that this is a mock price until there are actual Chainlink nodes on the testnet).

const linkIssuer = E(home.wallet).getIssuer('Testnet.$LINK');
const linkBrand = await E(linkIssuer).getBrand();
const linkAmount = AmountMath.make(linkBrand, 30 * 10 ** 18);
const usdBrand = await E(E(home.wallet).getIssuer('Testnet.$USD')).getBrand();
const { quoteAmount: { value: [{ amountOut: usdAmount, timestamp }] } } = await E(home.priceAuthority).quoteGiven(linkAmount, usdBrand);

Any API

To use Chainlink's Any API, you need to get an instance of the Low-level Oracle Query Contract and submit a query of the form:

{
  jobId: <Chainlink JobId>,
  params: { ...<job parameters> }
}

The oracle node returns its result, which is a JSONable value such as a string. This is sent as your query's reply.

You can test these queries against a locally-running Chainlink node that you control. Follow the Chainlink integration instructions to set it up.

There is also a more limited local node that emulates part of the Chainlink API without having to run Docker containers. This is the local (mock) builtin oracle.