Expose json rpc config to plugins through JsonRpcConfigurationService

[antonydenyer]

PR description

Expose json rpc config to plugins through JsonRpcConfigurationService.
This is instead of exposing generic untyped arguments as explored in #2661

[atoulme]

Do you also need cors host and allowlist?

[antonydenyer]

I did ponder that, would you need it? If you're inside the plugin running on the same machine I think all you need to know is what address it's bound to.

Now, you might need all the tls info, but then we're down the path of exposing all the cert stuff too, at that point you may as well just pass over JsonRpcConfiguration. The difficulty with this is that it's built and validated after the register method is called in the plugins.

I think the root cause is #2703 and the bootstrapping process of besu should be something like:

• load besu config
• load plugin config
• clean/normalise config (cast to types etc)
• validate options (e.g miner-enabled with no coinbase address)
• make normalised config available to besu and plugins
  ...

but, this addresses what I immediately need.

[vmichalik]

btw if you hadn't seen it already, #1317 requests this functionality

[antonydenyer]

I ended up working around the issue in the end by getting what I wanted from picocli. It's a hack and relies on us continuing to use picocli.

@Option(
      names = {"--plugin-permissioning-rpc-http-port"},
      defaultValue = "--rpc-http-port",
      hidden = true,
      preprocessor = BesuPreprocessor.class)
  private Integer port;


public static class BesuPreprocessor implements CommandLine.IParameterPreprocessor {
    @Override
    public boolean preprocess(
        final Stack<String> args,
        final CommandLine.Model.CommandSpec commandSpec,
        final CommandLine.Model.ArgSpec argSpec,
        final Map<String, Object> info) {
      argSpec.setValue(commandSpec.findOption(argSpec.defaultValue()).getValue());
      return true;
    }
  }

I don't think we should document this as 'the way to do it' but leaving here for reference until an agreement can be reached on how to expose config to plugins.