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Event notifications

  • Also referred to as "Event stream subscriptions"
  • Asynchronous events
  • Allow a plugin to subscribe to event topics such that CLN will send the plugin a push notification whenever events corresponding to such topics occur.
  • For events where it doesn’t matter how many plugins are listening to the event or in what order the event is processed.
  • Topics include:
    • channel_opened
    • connect
    • sendpay_success
    • block_added

For the full list of topics, see the official docs.

Exercise: Add an event stream subscription to your plugin

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

@plugin.subscribe("connect")
def on_connect(plugin, id, address, **kwargs):
    plugin.log("Received connect event for peer {}".format(id))


@plugin.subscribe("disconnect")
def on_disconnect(plugin, id, **kwargs):
    plugin.log("Received disconnect event for peer {}".format(id))

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

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

Grab Node 1’s pubkey and listening address:

l1-cli getinfo

Now paste the connection info for Node 1 into this connect command from Node 2:

l2-cli connect <Node 1’s pubkey>@<hostname>:<port>

Now check Node 1's logs to make sure your callback ran.

Try the same thing with your disconnect subscription:

l2-cli disconnect <Node 1’s pubkey>
  • Add an event stream subscription
  • Test that it works as expected