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Plugin Options

  • Command line options passthrough allows plugins to register their own command line options that are exposed through lightningd so that only the main process needs to be configured.
  • Options can also be passed from the config file.
  • Option values are not remembered when a plugin is stopped or killed, but can be passed as parameters to plugin start.

Exercise: Add an option to your plugin

Add this code to your main.rs file (hint: insert this before .dynamic()):

.option(options::ConfigOption::new(
    "name",
    options::Value::String("World".to_string()),
    "Recipient of the greeting. Defaults to 'World'",
))

Next, add a new method testmethod_option RPC method to use your option in that call.

.rpcmethod("testmethod_option", "This is a test", testmethod_option)
async fn testmethod_option(p: Plugin<()>, _v: serde_json::Value) -> Result<serde_json::Value, Error> {
    Ok(json!(format!("Hello, {:?}", p.option("name").unwrap())))
}

Note we renamed _p to p because we are actually using the plugin state, which was previously ignored. The plugin state p contains our options.

Now let's test!

Rebuild your plugin:

cargo build

Now go to the shell and stop your plugin:

l1-cli plugin stop rust-plugin

Now start your plugin, inserting a value for your new option:

l1-cli -k plugin subcommand=start plugin=$(pwd)/target/debug/rust-plugin name='<insert name here>'

Now invoke the new testmethod_option RPC method:

l1-cli testmethod_option

Try it with various arguments, and see what happens.

  • Add an option
  • Test that it works as expected