Feature: work with pruned node

[prusnak]

Since https://github.com/bitcoin/bitcoin/pull/20295 has been merged, it should be possible to run electrs against pruned node. If we encounter a block that is not cached, we can fetch it via the getblockfrompeer RPC call.

[Kixunil]

Note that btc-rpc-proxy should be usable today :) (but didn't try with electrs yet).

Concept ACK as long as it doesn't unconditionally increase minimal required Core version.

[Sjors]

Just note that getblockfrompeer doesn't wait for the block and doesn't fail if a given peer doesn't have it. So you'll have to work around that, or improve the RPC.

[leffw]

ACK

[timaschew]

Any update on this?

[antonilol]

will this getblockfrompeer the entire pruned part of the locally stored chain for the initial index?

for queries this wont improve privacy, if you request a bunch of blocks, simply making an address list and intersecting them can show the query address

[Kixunil]

@antonilol oh, that's a good point! Leaking privacy makes electrs pretty much pointless unless we query over separate Tor circuits which would be very slow.