Help with Plugins

[DerEwige]

Hello everyone,

I'm currently trying to write a plugin for eclair.

The plugin is in Java and I've managed to setup the project with all the dependencies.
I've so far only implemented a small par in the onSetup function to read the datadir form the Setup and then load the plugin config.
I wanted to test if the plugin could be loaded and read the config.
But as I don’t want to boot up a real node every time I want to do some small tests. I’ve tried to make a test class that calls the functions defined of the interface to check if they work.
But the parameters that get passed into those functions (e.g. the Setup object) are not trivial and I am not familiar with scala.

So I really struggle to create a proper Setup object to pass into the first function for testing.

I’ve looked through the source of the project if there are any mokup node setups for testing, but did not find it.

I would appreciate some pointers on how to test my plugin without loading it by a real node.

[dpad85]

Regarding the Setup parameters, it's often painful to use Scala objects from Java, but it can be done. Options and collections must be converted, and implicits must be provided. For example, with the Setup object:

final File datadir = new File(System.getProperty("user.home"), "foobar");
final Set<PluginParams> params = new HashSet<>();
final Option none = None$.MODULE$;
final ActorSystem system = ActorSystem.apply("system");

final Setup setup = new Setup(
  datadir,
  JavaConverters.asScala(params).toSeq(),
  none, // you'll get type check warnings there, but it should work
  none,
  system
);
...

Though AFAICT creating a Setup object will actually start a node, which is not what you wanted.

[dpad85]

What version of Java are you using? If you are using JDK17, you may have issues such as this. If so, try using OpenJDK 11 which is the recommended version.

[DerEwige]

I'm using Microsoft OpenJDK 11.0.15 LTS as I run the whole thing on windows.
Which makes my hole setup a bit more complicated.

But the good news is:
I gave up on trying to build up my own mokup node class and instead loaded my plugin into the real node and it worked.

    2022-07-05 12:38:12,300 INFO  fr.acinq.eclair.Plugin - loading 1 plugins
    2022-07-05 12:38:12,305 INFO  fr.acinq.eclair.Boot - loaded plugin ChannelDBPlugin
    2022-07-05 12:38:13,138 INFO  a.e.slf4j.Slf4jLogger - Slf4jLogger started
    2022-07-05 12:38:15,879 INFO  fr.acinq.eclair.Setup - hello!
    2022-07-05 12:38:15,883 INFO  fr.acinq.eclair.Setup - version=0.7.0 commit=a804905
    2022-07-05 12:38:15,885 INFO  fr.acinq.eclair.Setup - datadir=C:\Users\*******\.eclair
    2022-07-05 12:38:15,886 INFO  fr.acinq.eclair.Setup - initializing secure random generator
    2022-07-05 12:38:15,951 INFO  f.a.eclair.NodeParams - use seed file: C:\Users\********\.eclair\node_seed.dat
    2022-07-05 12:38:15,953 INFO  f.a.eclair.NodeParams - use seed file: C:\Users\*******\.eclair\channel_seed.dat
    2022-07-05 12:38:16,041 INFO  f.a.secp256k1.Secp256k1 - secp256k1 library successfully loaded
    2022-07-05 12:38:16,105 INFO  fr.acinq.eclair.Setup - instanceid=**********************************
    2022-07-05 12:38:16,959 INFO  f.a.e.t.TorProtocolHandler - Tor version 0.4.7.7
    2022-07-05 12:38:17,287 INFO  fr.acinq.eclair.Setup - Tor address Tor3(***********************************,9735)
    2022-07-05 12:38:17,368 INFO  fr.acinq.eclair.Setup - using plugin=ChannelDB

So my project setup should be ok now.
Jar file generetated is in the correct format.
The node successfully loads the jar and the plugin from within.

Next step is to figure out how to write to the same loggerfrom the pugin as the node.
Gotta read up on slf4j.

After that I can actually start with the real plugin :D

Thanks again for your support

[DerEwige]

Ok. Now I understand how the logging works.
I successfully logged into the eclair log with my own class name.

Next step: figure out on how to subscribe to the info my plugin needs.
Afaik that is done via onKit(Kit kit)?

[dpad85]

Once you got access to the kit, you know the node has been bootstrapped, and you have access to internal actors and data if you need them.

To subscribe to events in Java, here's an example:

• Java code creating a custom actor and subscribing that actor to various events here;
• the code for that actor here, with the method processing the incoming events.

The code linked above is not from a plugin but from an app that uses eclair as a library. So the context is different, but having the syntax may be helpful.

For an example of an actual plugin (written in Scala but it's quite readable), you can check this repository. In particular, you can see that this plugin provides the kit to a WatchdogSync actor when onKit is called.

[DerEwige]

Yeah I was using the eclair-alarmbot-plugin as reference for my plugin.
But as I never used akka before I really had problems to translate the akka specific parts into java.

I was eliminating one error after another just to get another one for hours.

But the examples from the app really helped.

I fially got it running:

2022-07-05 19:43:48,584 INFO  f.a.e.b.b.zmq.ZMQActor - connected to tcp://127.0.0.1:29000
2022-07-05 19:43:48,584 INFO  f.a.c.WatchdogSync - received unknown message

The second line is my plugin handling the ZMQ event with the default handler

[DerEwige]

Thanks again for helping me out @dpad85

The first part of what I wanted to do is working just fine.
I'm writing all information regarding failed and sent payments to a custom database.
This information is then used to analyse all nodes and channels in the neighbourhood of my node.
As a result I get probability values for each channel of the entire lightning network.
(Channels not in the database just get the average probability of the channels in the database)

I would now like to use this channel probability in rout finding.
From what I’ve seen, this is not possible with just a plugin and I have to do further changes to the node software.

I guess this would be the simplest solution:

• Create new Interface ProbabilityProvider with one function taking a channel and returning the probability.
• Use the same mechanism to load Classes for Plugin interface, to Load ProbabilityProvider from JAR.
• Add a field to the config to define the class of a custom probability provider. And a switch to turn it on.
• In the Graph.scala check for the switch. Get the class. Use the custom probability function on the edge.
• Define an experiment to use failure cost (with the custom probability)
• Use the experiment when finding route

If you have any suggestions on how to make it simpler, it would be appreciated

[t-bast]

This would require a lot of internal changes to eclair without clear benefits, so it's quite unlikely that it will be done.

I think a better first step is to have your plugin implement a completely separate path-finding and expose a custom API to use this path-finding algorithm instead of eclair's path-finding?

[DerEwige]

@t-bast
Hey I've already used a different approach.

I enabled this setting in the conf file:
randomize-route-selection = true

Now instead of one route I get 3.
Then I just calculate my fitness function for all the different routes I get and choose the best one.

I’ve also tested other values instead of 3 by changing the constant in the source and recompiling the node. But it was to much of a resource burden for the added benefit. So I went back to 3.

This method of getting multiple routes, than evaluating them according to my fitness function and then selecting the winner works fine for me.