Plugin for turning off a light via MQTT when the printer starts / finishes printing - depends on the MQTT plugin

mqtt-lights-plugin.py

import octoprint.plugin

class MqttLightsPlugin(octoprint.plugin.StartupPlugin, octoprint.plugin.EventHandlerPlugin):

    def __init__(self):
        self.mqtt_publish = lambda *args, **kwargs: None

    def on_after_startup(self):
        helpers = self._plugin_manager.get_helpers("mqtt", "mqtt_publish")
        if helpers:
            if "mqtt_publish" in helpers:
                self.mqtt_publish = helpers["mqtt_publish"]

    def on_event(self, event, payload):
        if event == 'PrintStarted':
            self.mqtt_publish("homie/printerlight/switch/on/set", "true")    
        if event in ['PrintFailed', 'PrintDone', 'PrintCancelled']:
            self.mqtt_publish("homie/printerlight/switch/on/set", "false")

__plugin_implementations__ = [MqttLightsPlugin()]