DEPRECATED

With Uniswap moving to v3 which contains built-in price history, this project is no longer necessary for most users. On top of that, there have been a couple open issues on this repository for a while that are important to get addressed but will require a significant amount of work. One is required to make the SDK work with London (EIP-1559), and the other is updating the contracts to work with newer versions of Solidity. Given that I am unlikeley to put in the time to actually address either of these issues, I'm marking this repository as deprecated.

Please note, the code is CC0 licenced, which means you can do whatever you want with it without permission. I encourage anyone who is interested in taking over maintenance to fork this repository and do so. If you show a willingness to maintain it (like fixing the two afformentioned issues) I would be happy to link to your fork in this readme.

uniswap-oracle

A general purpose price feed oracle built on Uniswap v2 that supports arbitrary time windows (up to 256 blocks) and doesn't require any active maintenance.

🎊 Finally, an on-chain trustless and censorship resistant oracle! 🎉

Unlike other Uniswap v2 based oracles, this one does not require regular maintenance by either an altruistic or incentivized party. Anyone with access to an Ethereum node can generate a proof of Uniswap's storage from up to 256 blocks ago and submit it for on-chain validation. You can then use that validated proof to calculate the average price between the current block and the supplied proof's block so you are protected from short-term price manipulation.

Community/Support

In the News

https://medium.com/@epheph/using-uniswap-v2-oracle-with-storage-proofs-3530e699e1d3

Usage

npm install @keydonix/uniswap-oracle-contracts @keydonix/uniswap-oracle-sdk

Optionally:

npm install @keydonix/uniswap-oracle-sdk-adapter

See a fully functional example in demo/contracts/PriceEmitter.sol and demo/source/demo.ts. Documentation here is a bit terse because the example is so small that it is probably easier to just read it!

pragma solidity 0.6.8;
pragma experimental ABIEncoderV2;

import { UniswapOracle } from  "@keydonix/uniswap-oracle-contracts/source/UniswapOracle.sol";
import { IUniswapV2Pair } from "@keydonix/uniswap-oracle-contracts/source/IUniswapV2Pair.sol";

contract PriceEmitter is UniswapOracle {
	event Price(uint256 price);

	function emitPrice(IUniswapV2Pair exchange, address denominationToken, uint8 minBlocksBack, uint8 maxBlocksBack, UniswapOracle.ProofData memory proofData) public returns (uint256 price, uint256 blockNumber) {
		(price, blockNumber) = getPrice(exchange, denominationToken, minBlocksBack, maxBlocksBack, proofData);
		emit Price(price);
	}
}

import * as OracleSdk from '@keydonix/uniswap-oracle-sdk'
import * as OracleSdkAdapter from '@keydonix/uniswap-oracle-sdk-adapter'

// create the getters the SDK needs from an Ethereum instance off the window.  you could use `window.web3.currentProvider` instead of `window.ethereum` if that is what is available
const getStorageAt = OracleSdkAdapter.getStorageAtFactory(window.ethereum)
const getProof = OracleSdkAdapter.getProofFactory(window.ethereum)
const getBlockByNumber = OracleSdkAdapter.getBlockByNumberFactory(window.ethereum)

// estimate the moving average price off-chain for presentation in your UI
const estimatedPrice = OracleSdk.getPrice(getStorageAt, getblockByNumber, uniswapExchangeAddress, denominationTokenAddress, blockNumber)

// get the proof from the SDK
const proof = await OracleSdk.getProof(getStorageAt, getProof, getBlockByNumber, uniswapExchangeAddress, denominationTokenAddress, blockNumber)

// inside this contract call we'll have trustless access to a Uniswap average price between `blockNumber` and `currentBlockNumber`
await priceEmitter.emitPrice(uniswapExchangeAddress, denominationTokenAddress, minBlocksBackAllowed, maxBlocksBackAllowed, proof)

Developing

Tool Requirements

NodeJS, NPM, Docker

Optional

VSCode (life is simpler with this, but not required)

VSCode

If you are using VSCode, you can run npm install in each directory (one time operation) and then Tasks Run Task > all the things to bootstrap everything. From there you can Debug: Select and Start Debugging > run demo or Debug: Select and Start Debugging > run tests.

Building

Contracts

These are published to NPM as-is, demo project compiles and tests them.

SDK

cd sdk
npm install # one time

npm run build

SDK Adapter

cd sdk-adapter
npm install # one time

npm run build

Demo

Depends on Contracts and SDK

cd demo
npm install # one time

npm run build # compiles contracts

Running

cd demo
docker-compose up --force-recreate --always-recreate-deps --abort-on-container-exit --remove-orphans --renew-anon-volumes
npm run demo

Testing

cd demo
docker-compose up --force-recreate --always-recreate-deps --abort-on-container-exit --remove-orphans --renew-anon-volumes
npm run test