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RPC Methods

  • You can define custom behavior for any lightning-cli method by registering that method with lightningd in your getmanifest response.
  • Whenever lightning-cli <method> [options] is called, CLN will pass the method and options back to the plugin, which can handle the call and respond however it wants.
  • Can register any number of RPC methods, as long as the method names aren’t already taken.
  • If an RPC method is already taken when the plugin registers the method name, the plugin is killed.

Exercise: Add an RPC method to your plugin

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

@plugin.method("hello")
def hello(plugin, name="world"):
    """This is the documentation string for the hello-function.
    It gets reported as the description when registering the function
    as a method with `lightningd`.
    """
    greeting = "Hello"
    s = '{} {}'.format(greeting, name)
    plugin.log(s)
    return s

Now let's test! Restart your plugin:

l1-cli plugin stop helloworld.py && l1-cli plugin start $(pwd)/python-plugin/helloworld.py

Now invoke your new RPC method:

l1-cli hello

Try it with an argument:

l1-cli hello <your name>

Try causing the rpc call to throw an error:

l1-cli hello too many arguments
  • Add an RPC method
  • Test that it works as expected