Who should tell client where to connect for blockchain data

[dpc]

For things like deposits and withdrawals and some other stuff the client needs data from L1. Unfortunately most clients can't be expected to have a bitcoind around, and needs to know where to alternatively connect.

The settings here is: backend kind and url. E.g. electrum + https://sometrustedelectrum:53234.

Currently we kind of hack around it in unexpected ways.

Who client/user can trust with providing correct data and privacy?

We probably should obsolete the wallet-module bitcoin rpc config (cfg.default_bitcoin_rpc), as being part of consensus makes it unchangeable and meta seems like the right place for it.

Possible reasonable ways to pass to client bitcoin rpc configuration, in order of preference (IMO):

• by the user, e.g. in the App UI, passed to the client via env var or direct configuration passed to the client/module
• defaults(?) by the integrator app, passsed the same way
• by the Federation, via meta
• some built-in defaults

[m1sterc001guy]

If I recall correctly, we also have an issue using bitcoind for RPCs on the client: https://github.com/fedimint/fedimint/issues/2955. So the lack of configurability here is also hiding a bug :/

The fix for this will hopefully be unblocked after we upgrade to bitcoin 0.30