Improving currencyrate plugin by enaples · Pull Request #9011 · ElementsProject/lightning

enaples · 2026-03-31T15:10:59Z

Important

26.04 FREEZE March 11th: Non-bugfix PRs not ready by this date will wait for 26.06.

RC1 is scheduled on March 23rd

The final release is scheduled for April 15th.

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The changelog has been updated in the relevant commit(s) according to the guidelines.
Tests have been added or modified to reflect the changes.
Documentation has been reviewed and updated as needed.
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Currencyrate plugin changes

As mentioned in #9010,

Check on RPC argument number added
Show max three decimal digits
Added source argument to the currencyrate RPC call
Added "Example" on RPC documentation

Info Needed

I would personally suggest to add a README.md file in the currencyrate plugin folder reporting how to configure new sources in the config file, plus some best practice using reckless to add and disable sources without restarting the node.

Lagrang3 · 2026-04-01T13:25:41Z

plugins/currencyrate-plugin/src/main.rs

 const MSAT_PER_BTC: f64 = 1e11;

+fn round_to_3dp(price: f64) -> f64 {
+    format!("{:.3}", price).parse::<f64>().unwrap_or(price)


Instead of moving from f64 to a string and then back again to f64, it would be better to do some purely mathematical operation.
eg. output = (input*1000.0).round() / 1000.0;

to always get 3 decimal places you must return a String:

fn round_to_3dp(price: f64) -> String { format!("{:.3}", (price * 1000.0).round() / 1000.0) }

This method is not that reliable. See here the comment for very large number. That's why I opted for the f64 --> String --> f64 solution.

I need to return again f64 since the price is used to compute the median, so it is better to return f64 again in my opinion.

Oh, the linked issue said to always have 3 decimal places not at most 3. So this is fine then if we can live with always rounding toward 0.

…cyrate` command

contrib/msggen/msggen/schema.json

Changelog-None

daywalker90 · 2026-04-02T09:22:49Z

I would personally suggest to add a README.md file in the currencyrate plugin folder reporting how to configure new sources in the config file

We can do that, but personally i go to https://docs.corelightning.org/reference/lightningd-config first to see documentation on config options and we have the currencyrate options with instructions on how they need to be written included there.

, plus some best practice using reckless to add and disable sources without restarting the node.

No sure if it can be done with reckless but it can be done with just the plugin command e.g.:

lightning-cli plugin stop cln-currencyrate

then to add a source:

lightning-cli plugin -k subcommand=start plugin=/media/addonssd/dev/lightning/plugins/cln-currencyrate currencyrate-add-source="test,https://test.com/{currency},rate"

But keep in mind that afaik any events happening while the plugin is stopped will have their currencyrate missing.

daywalker90 · 2026-04-02T11:26:59Z

plugins/currencyrate-plugin/src/main.rs

        Value::Array(values) => {
+            if values.len() > 2 {
+                return Err(anyhow!(
+                    "Too many arguments: expected at most 2 (amount currency), got {}",


nit: change this to expected 2.

daywalker90 · 2026-04-02T11:27:32Z

plugins/currencyrate-plugin/src/main.rs

                .to_owned();
            (amount, currency.to_uppercase())
        }
        Value::Object(map) => {


We should then also do the same check for object based queries here aswell.

daywalker90 · 2026-04-02T11:27:51Z

plugins/currencyrate-plugin/src/main.rs

+            let source = values.get(1).and_then(|v| v.as_str()).map(str::to_owned);
+            (currency, source)
        }
        Value::Object(map) => {


We should then also do the same check for object based queries here aswell.

daywalker90 · 2026-04-02T11:30:07Z

plugins/currencyrate-plugin/src/main.rs

        Value::Array(values) => {
+            if values.len() > 1 {
+                return Err(anyhow!(
+                    "Too many arguments: expected at most 1 (currency), got {}",


nit: "expected 1"

daywalker90 · 2026-04-02T11:30:24Z

plugins/currencyrate-plugin/src/main.rs

                .to_owned();
            currency.to_uppercase()
        }
        Value::Object(map) => {


We should then also do the same check for object based queries here aswell.

daywalker90 · 2026-04-02T12:14:25Z

plugins/currencyrate-plugin/src/main.rs

-                .to_owned();
-            currency.to_uppercase()
+                .to_uppercase();
+            let source = values.get(1).and_then(|v| v.as_str()).map(str::to_owned);


We do allow sources to be named as numbers only and this would then cause currencyrate to silently ignore the sourrce and return a median result. I suggest changing this to:

let source = values.get(1).and_then(|v| { v.as_str() .map(str::to_owned) .or_else(|| v.as_number().map(std::string::ToString::to_string)) });

daywalker90 · 2026-04-02T12:14:52Z

plugins/currencyrate-plugin/src/main.rs

-                .to_owned();
-            currency.to_uppercase()
+                .to_uppercase();
+            let source = map.get("source").and_then(|v| v.as_str()).map(str::to_owned);


Same as above:

let source = map.get("source").and_then(|v| { v.as_str() .map(str::to_owned) .or_else(|| v.as_number().map(std::string::ToString::to_string)) });

daywalker90 · 2026-04-02T12:20:27Z

Usually we would use setconfig to change options dynamically but since here we have multi options it's not possible until something like #8751. Then we could change sources without restarting the plugin or node or extra rpc methods(yikes).

enaples requested a review from daywalker90 March 31, 2026 15:11

enaples added this to the 26.06 milestone Mar 31, 2026

enaples changed the title ~~plugin: round to the tird digit and adding source argument to `curren…~~ Improving currencyrate plugin Mar 31, 2026

enaples linked an issue Mar 31, 2026 that may be closed by this pull request

currencyrate plugin UI improvement proposals #9010

Open

madelinevibes added the 26.04 RC This PR needs to go into the next release candidate for 26.04 label Mar 31, 2026

madelinevibes requested a review from rustyrussell March 31, 2026 16:19

sangbida removed the 26.04 RC This PR needs to go into the next release candidate for 26.04 label Apr 1, 2026

Lagrang3 reviewed Apr 1, 2026

View reviewed changes

daywalker90 force-pushed the improve-currencyrate-plugin branch from 1f75db1 to 3ef67e3 Compare April 2, 2026 08:15

daywalker90 requested a review from cdecker as a code owner April 2, 2026 08:15

enaples added 3 commits April 2, 2026 10:16

plugin: round to the tird digit and adding source argument to `curren…

29306bb

…cyrate` command

plugin: add control on RPC arguments

388a5b6

docs: update currencyrate docs

203a71f

daywalker90 force-pushed the improve-currencyrate-plugin branch from 3ef67e3 to d945873 Compare April 2, 2026 08:16

daywalker90 reviewed Apr 2, 2026

View reviewed changes

contrib/msggen/msggen/schema.json Show resolved Hide resolved

enaples and others added 2 commits April 2, 2026 10:27

pytest: test new features and improvements of currencyrate plugin

2dab5a3

msggen: add source argument for currencyrate

1a74aaa

Changelog-None

daywalker90 force-pushed the improve-currencyrate-plugin branch from d945873 to 1a74aaa Compare April 2, 2026 08:27

daywalker90 requested changes Apr 2, 2026

View reviewed changes

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enaples commented Mar 31, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Currencyrate plugin changes

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daywalker90 commented Apr 2, 2026

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daywalker90 commented Apr 2, 2026

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enaples commented Mar 31, 2026 •

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