Chainlink Integration

This document explains how to consume Chainlink oracles (opens new window) 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 (opens new window) can initiate a job on a single oracle and return its results

We have tested these features with actual Chainlink oracle software (opens new window).

Note: Chainlink has not yet (as of 2020-11-16) 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 (opens new window) 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 (opens new window).