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 helloworld.py file (hint: make sure you insert this before plugin.run()):

plugin.add_option('greeting', 'Hello', 'The greeting I should use.')

Next, edit your hello RPC method from the previous step to use your option in that call:

Change the line that says:

greeting = "Hello"

To use your option:

greeting = plugin.get_option('greeting')

Now let's test! Go to the shell and stop your plugin:

l1-cli plugin stop helloworld.py

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

l1-cli -k plugin subcommand=start plugin=$(pwd)/python-plugin/helloworld.py greeting='A crazy'

Now invoke the updated hello RPC method:

l1-cli hello

Try it with various arguments, and see what happens.