Pyth SDK Terra

This crate provides utilities for reading price feeds from the pyth.network oracle on the Terra network. The crate includes a library for reading and using Pyth data feeds in Terra.

Usage

:grey_exclamation: Please follow consumer best practices when consuming Pyth data.

Read price

For reading the price you just need to call query_price_feed function within your contract with the id of the price feed.

You can find the contract address and price feed ids in the section Contracts and Price Feeds below.

let price_feed: PriceFeed = query_price_feed(deps.querier, contract_addr, id)?.price_feed;

Example contract

Checkout Example Terra Contract as an example which uses Pyth Terra contract to fetch a price.

Price Feed and Price API

The PriceFeed struct contains several useful functions for working with the price. Some of these functions are described below. For more detailed information, please see the crate documentation.

Get the current price

Read the current price from a PriceFeed:

let current_price: Price = price_feed.get_current_price().ok_or(StdError::not_found("Current Price is not available"))?;
println!("price: ({} +- {}) x 10^{}", current_price.price, current_price.conf, current_price.expo);

The price is returned along with a confidence interval that represents the degree of uncertainty in the price. Both values are represented as fixed-point numbers, a * 10^e. The method will return None if the price is not currently available.

Non-USD prices

Most assets in Pyth are priced in USD. Applications can combine two USD prices to price an asset in a different quote currency:

let btc_usd: Price = ...;
let eth_usd: Price = ...;
// -8 is the desired exponent for the result 
let btc_eth: Price = btc_usd.get_price_in_quote(&eth_usd, -8);
println!("BTC/ETH price: ({} +- {}) x 10^{}", price.price, price.conf, price.expo);

Price a basket of assets

Applications can also compute the value of a basket of multiple assets:

let btc_usd: Price = ...;
let eth_usd: Price = ...;
// Quantity of each asset in fixed-point a * 10^e.
// This represents 0.1 BTC and .05 ETH.
// -8 is desired exponent for result
let basket_price: Price = Price::price_basket(&[
    (btc_usd, 10, -2),
    (eth_usd, 5, -2)
  ], -8);
println!("0.1 BTC and 0.05 ETH are worth: ({} +- {}) x 10^{} USD",
         basket_price.price, basket_price.conf, basket_price.expo);

This function additionally propagates any uncertainty in the price into uncertainty in the value of the basket.

Client-side Usage

You can use the provided schemas in the schema directory to query the terra contract client side.

The query should look like:

{
    "price_feed": {
        "id": [249, 192, 23, ..., 163, 27] // id of the price feed as an array of bytes
    }
}

By going to the contract address in Terra Finder you can try and make a query for a price feed and see the result.

Contracts and Price Feeds

Currently Pyth is only available in testnet network.

Testnet

The contract address is terra1hdc8q4ejy82kd9w7wj389dlul9z5zz9a36jflh.

List of available Price Feeds and their ids:

Notes

• :warning: num_publishers and max_num_publishers in PriceFeed are currrently unavailable and set to 0.