[Hero & Hertz] 'bitshares-pricefeed' referencing bitUSD | BTS_Tools referencing BTC:USD (bitUSD|BTC:USD)

[grctest]

Summarized snippets of Wackou's price feed script:

btc_price = feeds_bts_btc.price()

feeds_btc_usd = get_multi_feeds('get', [('BTC', 'USD')],
                                active_providers_bts({providers.BitcoinAverage,
                                                      providers.CoinMarketCap,
                                                      providers.Bitfinex,
                                                      providers.Bitstamp}))
btc_usd = feeds_btc_usd.price()
usd_price = btc_price * btc_usd
feeds['HERO'] = usd_price / (1.05 ** ((pendulum.today() - pendulum.Pendulum(1913, 12, 23)).in_days() / 365.2425))

Current Hero&Hertz Yaml USD reference:

# ... namely "USD" a.k.a. "bitUSD"
ref_asset: USD

There's a difference in price BTS:USD reference between the two Bitshares price feed libraries. @xeroc's scripts reference bitUSD (decentralized, reliant on bitUSD functioning properly, less volatile?) meanwhile @wackou's price feed scripts reference external BTC:USD price feeds (Reliant on centralized exchanges, potentially vulnerable to manipulation, potentially avoid following bitUSD into a blackswan).

What's the appropriate USD reference for Hero (and consequentially Hertz) bitUSD:BTS and/or BTC:USD?

Cheers

[Zapata]

From what I understand from the code, @xeroc's script use bitUSD market price. There is usually a 10% spread between the market price and the settlement price.

Another approach could be to use bitUSD settlement price/current feed (= the median price of all the feeds).
This way you rely on Bitshares decentralization of the price feed to get a proper price.

I think if you already publish the price of USD:BTS it's better to use your computed price (this way USD and HERTZ price will be consistent), but if you publish only HERTZ, the best it's to get bitUSD settlement price.

I have added BitsharesFeed source for this purpose in my repo.

[grctest]

BSIP 76 (bitshares/bsips#221) has now set fixed (fake) price feeds for bitUSD.

Since this price feed script uses bitUSD as the price feed reference it's now producing inaccurate Hertz price feeds.

Can an alternative to bitUSD be provided for Hertz to become accurate again?

[Zapata]

Note that using my fork (which is used by most of the witnesses), the USD price used depends of the configuration file.
All three sources are possible:

• Bitshares USD feed:

    hero:
        klass: Hero
    bitshares_usd_feed:
        klass: BitsharesFeed
        assets:
            - USD

• USD/BTS from Dex:

    hero:
        klass: Hero
    bitshares_usd_market:
        klass: Graphene
        quotes:
            - USD
        bases:
            - BTS
        aliases:
            USD: BITUSD

• USD/BTS from CEX, see this sample config