wallet: add set tx fee endpoint

[tuxcanfly]

Refs #512

[BluSyn]

Great! Would suggest also adding a GET /fee endpoint, since we are now making /fee a top-level resource, it makes it more "RESTful" + probably useful to see the current fee rate.

[tuxcanfly]

Needs tests. Guess we could top this off with a admin command from bwallet cli as well. Thoughts @BluSyn @bucko13 ?

[codecov-io]

Codecov Report

Merging #518 into master will decrease coverage by 0.02%.
The diff coverage is 13.33%.

@@            Coverage Diff             @@
##           master     #518      +/-   ##
==========================================
- Coverage   52.88%   52.86%   -0.03%     
==========================================
  Files         104      104              
  Lines       27700    27715      +15     
  Branches     4748     4750       +2     
==========================================
+ Hits        14649    14651       +2     
- Misses      13051    13064      +13

Impacted Files	Coverage Δ
lib/wallet/http.js	43.8% <13.33%> (-0.76%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update f24a9b6...d06cb13. Read the comment docs.

[bucko13]

Yeah, I think that would make sense to keep bclient in sync with the server.

[nodech]

Bcoin HTTP API for fees does not use floats. E.g. Create TX -- we are using Satoshis at HTTP level, same for fees.
bclient should do conversion, but not HTTP.

Note: This won't persist.

[tonydspaniard]

This will force a fixed fee for a transaction?

[BluSyn]

This will force a fixed fee for a transaction?

Yes, however as nodar said:

Note: This won't persist.

I think we should add clear documentation about this.

1. By default the fee is 'floating' (uses fee estimation)
2. Setting the fee by http/rpc will make it 'fixed' for all future txs created
3. This setting will not persist between bcoin restarts

@tuxcanfly is it possible to 'reset' the behavior to 'floating' (fee estimation) after setting a fee using http/rpc? Doesn't seem obvious this is possible. Currently when I set it from rpc I always have to restart bcoin to return to using estimation. Perhaps allow null to return to default behavior.

Would also be cool to expose the rpc estimatefee <nblocks> over http, but that's a totally separate feature request.

[braydonf]

A configuration option could be a way to persist such fee rates, albiet it will require a restart.

Also setting the rate when creating each transaction could be another, with less side effects, way to have configuration here, if it's not already.

[nodech]

Probably best way would be to persist it within wallet database, even though it might need migration, I believe it can be implemented without migration as well (Don't crash when field is not there). You will have per wallet fee rates.

You can overwrite fee rates when creating transaction, it's there already.

[tynes]

Any updates on this PR? Seems like a candidate for getting merged

[pinheadmz]

Needs rebase on master. Test would be nice too. And since the client is now integrated into the repo, we could quickly add setfeerate and getfeerate to the CLI.