| .. Licensed to the Apache Software Foundation (ASF) under one |
| or more contributor license agreements. See the NOTICE file |
| distributed with this work for additional information |
| regarding copyright ownership. The ASF licenses this file |
| to you under the Apache License, Version 2.0 (the |
| "License"); you may not use this file except in compliance |
| with the License. You may obtain a copy of the License at |
| |
| .. http://www.apache.org/licenses/LICENSE-2.0 |
| |
| .. Unless required by applicable law or agreed to in writing, |
| software distributed under the License is distributed on an |
| "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| KIND, either express or implied. See the License for the |
| specific language governing permissions and limitations |
| under the License. |
| |
| Listeners |
| ========= |
| |
| Airflow gives you an option to be notified of events happening in Airflow |
| by writing listeners. Listeners are powered by `pluggy <https://pluggy.readthedocs.io/en/stable/>`__ |
| |
| Listener API is meant to be called across all dags, and all operators - in contrast to methods like |
| ``on_success_callback``, ``pre_execute`` and related family which are meant to provide callbacks |
| for particular dag authors, or operator creators. There is no possibility to listen on events generated |
| by particular dag. |
| |
| To include listener in your Airflow installation, include it as a part of an :doc:`Airflow Plugin </plugins>` |
| |
| |experimental| |
| |
| Interface |
| --------- |
| |
| To create a listener you will need to derive the |
| create python module, import ``airflow.listeners.hookimpl`` and implement the ``hookimpls`` for |
| events you want to be notified at. |
| |
| Right now Airflow exposes TaskInstance state change events. |
| Their specification is defined as ``hookspec`` in ``airflow/listeners/spec.py`` file. |
