Run Your Own Ethereum Oracle

Run your own simple Ethereum oracle implementation, fetching off-chain data from external APIs.

This project is mostly based on CryptoZombies oracle series, modified and ported to hardhat/ether.js.

Here is the architecture of the system.

Requirements

1. node js (tested on v16.13.1)
2. npx

Installation

npm install

Usage

Deploy DataOracle and OracleCaller contracts to hardhat local network.

# run local network
npx hardhat node
# deploy to local network
npx hardhat run --network localhost scripts/deploy.js

IMPORTANT: after deploying the contracts, change dataOracleAddress and oracleCallerAddress to the deployed addresses of each contracts in scripts/server.js and scripts/trigger-update-data.js.

Simulate data update

Assuming you have deployed the contracts.

Step 1: run sample server

This script will listen to new request events triggered from oracle caller contract and periodically process them.

node scripts/server.js

Step 2: run trigger update data script

This will tigger will call OracleCaller contract's updateData, emitting ReceivedNewRequestIdEvent event, which will trigger data fetching logic in scripts/server.js.

node scripts/trigget-update-data.js

If you look at scripts/server.js's output, you should be able to see something like this.

NEW EVENT - ReceivedNewRequestIdEvent: BigNumber { _hex: '0x0203', _isBigNumber: true }
NEW EVENT - DataUpdatedEvent: id = BigNumber { _hex: '0x0203', _isBigNumber: true } data = https://cdn.shibe.online/shibes/55a6c07e7965f3ca93ff64bcbcc6a4a7a62645de.jpg

Which shows that the request was listened by the server and the server triggered a data update to the contract.

Run tests

npx hardhat test