Plugin CLI options not bound until after register is called

[antonydenyer]

Description

As a plugin developer, I want access to the cli options that are pertinent to my plugin during the registration phase. The reason for this is that I may not wish to register my plugin if it's not enabled/configured correctly. The problem is that we have a catch 22 with regards to registering PicoCLIOptions. The only place you can register PicoCLIOptions is in the register method, this is, obviously, too late if you are expecting those parameters to be bound at that point in time.

@AutoService(BesuPlugin.class)
public class MyMetricsPlugin implements BesuPlugin {

  @Option(
      names = {"--plugin-metrics-enabled"},
      description = "Enable Metrics plugin")
  private boolean enabled;

  @Override
  public void register(final BesuContext context) {
    final PicoCLIOptions cmdlineOptions = context.getService(PicoCLIOptions.class).get();
    cmdlineOptions.addPicoCLIOptions("metrics", this);
   
    if (enabled) {
      // register metrics category
      ...
    }

  }
  ... 
}

Obviously, this will not work because enabled will always equal false.

We need a better way of allowing plugin developers to configure command-line arguments.

Options

Add an optional method to the BesuPlugin interface

Something like

  void initialize(PicoCLIOptions options);

would allow a plugin developer to call addPicoCLIOptions before register is called.

Always mixin BesuPlugin classes

Another option is to always 'mixin' the plugin class. This would mean that a plugin implementor would only be able to register options in a class that implements BesuPlugin. But would not need to explicitly call addPicoCLIOptions anywhere.

Backwards compatibility

Either option, or both, could be added whilst maintaining the current behaviour.

[macfarla]

@jflo @Gabriel-Trintinalia is this issue still relevant?

[jflo]

Yes, this is an important plugin lifecycle adjustment.