@core-ln/plugin

This package allows you to build plugins with core-ln.

This API is very similar to that of clightningjs.

Usage

Summary

• Methods
• Startup options
• Notifications
• Hooks
• Advanced usage

Methods

A method should take a JSON array as parameter and return either a valid JSON-encodable value:

#!/usr/bin/env bash
Function=Function//; node -m "$0" "$@"; exit

import { Plugin } from "c-lightning.ts";

const helloPlugin = new Plugin();
function sayHello(params) {
  if (!params || params.length === 0) {
    return 'Hello world';
  } else {
    return 'Hello ' + params[0];
  }
}
helloPlugin.addMethod('hello', sayHello, 'name', 'If you launch me, I\'ll great you !');
helloPlugin.start();

Or a promise:

#!/usr/bin/env bash
Function=Function//; node -m "$0" "$@"; exit

import { Plugin } from "c-lightning.ts";

const helloPlugin = new Plugin();
async function sayBye(params) {
  return Promise.resolve('Bye bye');
}
helloPlugin.addMethod('bye', sayBye, '', 'If you launch me, I\'ll say good bye');
helloPlugin.start();

Startup options

You can add a startup option to lightningd and make a method behave depending on it:

#!/usr/bin/env bash
Function=Function//; node -m "$0" "$@"; exit

import { Plugin } from "c-lightning.ts";

const helloPlugin = new Plugin();
async function sayBye(params) {
  return Promise.resolve('Bye bye ' + helloPlugin.options['byename'].value);
}
helloPlugin.addOption('byename', 'continuum', 'The name of whow I should say bye to', 'string');
helloPlugin.addMethod('bye', sayBye, '', 'If you launch me, I\'ll say good bye');
helloPlugin.start();

Notifications subscription

You can subscribe to lightningd notifications, the plugin will emit events upon their reception:

#!/usr/bin/env bash
Function=Function//; node -m "$0" "$@"; exit

import * as fs from 'fs';
import { Plugin } from "c-lightning.ts";

const listenPlugin = new Plugin();
listenPlugin.subscribe('warning');
listenPlugin.notifications.warning.on('warning', (params) => {
  fs.writeFile('log', params.warning.log, () => {});
});
listenPlugin.start();

Hooks subscription

You can subscribe to lightningd hooks:

#!/usr/bin/env bash
Function=Function//; node -m "$0" "$@"; exit

import * as fs from 'fs';
import { Plugin } from "c-lightning.ts";

const dbBackup = new Plugin();
function useLessBackup(params) {
  fs.writeFile('logDb', params.writes, () => {});
  return true;
}
dbBackup.addHook('db_write', useLessBackup);
dbBackup.start();

More

You can restrict RPC control over your plugin with

// myStaticPlugin cannot be stopped by RPC
const myStaticPlugin = new Plugin({ dynamic: false });

You can log to lightningd logs with myPlugin.log(message, logLevel), with the level defaulting to 'info'.

You can do some stuff at initialization (just before responding to the init message):

const myPlugin = new Plugin();
// "params" contains the params passed by `lightningd` along with the `init` message
myPlugin.onInit = function (params) {
	myPlugin.log('I\'m going to be initialized !!');
};

You can return a promise to a hook or a RPC method callback. This allows to not restrain the context of an RPC method or a hook result only to the registered callback. Here is an example from test/hodl.js which, well, hodl an HTLC..

const myWonderfulPlugin = new Plugin({dynamic: true});
myWonderfulPlugin.relasedHtlc = new EventEmitter();
myWonderfulPlugin.addHook('htlc_accepted', () => {
  myWonderfulPlugin.log('Ok, I won\'t release the HTLC, but will return!');
  return new Promise((resolve, reject) => {
    myWonderfulPlugin.relasedHtlc.on('released', () => {
      myWonderfulPlugin.log('Resolved');
      resolve({'result': 'continue'});
    });
  });
});
function releaseHtlc(params) {
  myWonderfulPlugin.log('Ok, finally I will release the HTLC and all the stuck liquidity.');
  myWonderfulPlugin.relasedHtlc.emit('released');
  return "OK";
}
myWonderfulPlugin.addMethod('releasehtlc', releaseHtlc, '', 'release an HTLC', '.');
myWonderfulPlugin.start();

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Check out our other packages

• @core-ln/base - Abstract API type definitions
• @core-ln/core - Connect over an unix socket
• @core-ln/rest - Client for c-lightning-REST