Allow dynamic option in python plugin

contrib/pyln-client/pyln/client/plugin.py

@@ -220,7 +220,8 @@ def __init__(self, stdout: Optional[io.TextIOBase] = None,
                  invoice_features: Optional[Union[int, str, bytes]] = None,
                  custom_msgs: Optional[List[int]] = None):
         self.methods = {
-            'init': Method('init', self._init, MethodType.RPCMETHOD)
+            'init': Method('init', self._init, MethodType.RPCMETHOD),
+            'setconfig': Method('setconfig', self._set_config, MethodType.RPCMETHOD)
         }
 
         self.options: Dict[str, Dict[str, Any]] = {}
@@ -389,7 +390,8 @@ def decorator(f: Callable[..., None]) -> Callable[..., None]:
     def add_option(self, name: str, default: Optional[str],
                    description: Optional[str],
                    opt_type: str = "string", deprecated: bool = False,
-                   multi: bool = False) -> None:
+                   multi: bool = False,
+                   dynamic=False) -> None:
         """Add an option that we'd like to register with lightningd.
 
         Needs to be called before `Plugin.run`, otherwise we might not
@@ -414,18 +416,19 @@ def add_option(self, name: str, default: Optional[str],
             'value': None,
             'multi': multi,
             'deprecated': deprecated,
+            "dynamic": dynamic
         }
 
     def add_flag_option(self, name: str, description: str,
-                        deprecated: bool = False) -> None:
+                        deprecated: bool = False, dynamic: bool = False) -> None:
         """Add a flag option that we'd like to register with lightningd.
 
         Needs to be called before `Plugin.run`, otherwise we might not
         end up getting it set.
 
         """
         self.add_option(name, None, description, opt_type="flag",
-                        deprecated=deprecated)
+                        deprecated=deprecated, dynamic=dynamic)
 
     def add_notification_topic(self, topic: str):
         """Announce that the plugin will emit notifications for the topic.
@@ -784,7 +787,7 @@ def print_usage(self):
         """)
 
         for method in self.methods.values():
-            if method.name in ['init', 'getmanifest']:
+            if method.name in ['init', 'getmanifest', 'setconfig']:
                 # Skip internal methods provided by all plugins
                 continue
 
@@ -864,7 +867,7 @@ def _getmanifest(self, **kwargs) -> JSONType:
         hooks = []
         for method in self.methods.values():
             # Skip the builtin ones, they don't get reported
-            if method.name in ['getmanifest', 'init']:
+            if method.name in ['getmanifest', 'init', 'setconfig']:
                 continue
 
             if method.mtype == MethodType.HOOK:
@@ -970,6 +973,12 @@ def verify_bool(d: Dict[str, JSONType], key: str) -> bool:
             return self._exec_func(self.child_init, request)
         return None
 
+    def _set_config(self, **_) -> None:
+        """Called when the value of a dynamic option is changed
+        For now we don't do anything.
+        """
+        pass
+
 
 class PluginStream(object):
     """Sink that turns everything that is written to it into a notification.

tests/plugins/dynamic_option.py

@@ -0,0 +1,12 @@
+#!/usr/bin/env python3
+from pyln.client import Plugin
+
+plugin = Plugin()
+
+plugin.add_option(
+    name="test-dynamic-config",
+    description="A config option which can be changed at run-time",
+    default="initial",
+    dynamic=True)
+
+plugin.run()

tests/test_plugin.py

@@ -4258,6 +4258,17 @@ def test_all_subscription(node_factory, directory):
     assert not l2.daemon.is_in_log(f'.*test_libplugin: all: connect.*')
 
 
+def test_dynamic_option_python_plugin(node_factory):
+    plugin = os.path.join(os.getcwd(), "tests/plugins/dynamic_option.py")
+    ln = node_factory.get_node(options={"plugin": plugin})
+    result = ln.rpc.listconfigs("test-dynamic-config")
+
+    assert result["configs"]["test-dynamic-config"]["value_str"] == "initial"
+
+    result = ln.rpc.setconfig("test-dynamic-config", "changed")
+    assert result["config"]["value_str"] == "changed"
+
+
 def test_renepay_not_important(node_factory):
     # I mean, it's *important*, it's just not "mission-critical" just yet!
     l1 = node_factory.get_node(options={'allow-deprecated-apis': True})