Dev-iL commented on code in PR #55743: URL: https://github.com/apache/airflow/pull/55743#discussion_r2354229301
########## airflow-core/docs/howto/sla-to-deadlines.rst: ########## @@ -0,0 +1,89 @@ + .. 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. + +Migrating from SLA to Deadline Alerts +===================================== + +Two different paradigms +----------------------- + +While the goal of the **SLA** and **Deadlines** features are very similar, they use two very different approaches +which makes it difficult to present a universal migration guide. Instead, this guide will lay out the major +differences and help you decide on the best approach for your use case. + +To begin with, we'll start by explaining the two approaches then go into how to find the right Deadline for your use case. + +SLA +^^^ + +When the dag run **finishes**, check the current time. If the time is greater than (logical_date + sla) then +execute ``sla_miss_callback``. If the Dag run never finishes, the SLA is never checked. + +Deadlines +^^^^^^^^^ + +When a Dag run **starts**, calculate and store (:ref:`DeadlineReference <built-in-deadline-references>` + interval). +Every pass of the scheduler loop (default 5 seconds, set by ``scheduler_heartbeat_sec``) if any of those times have +passed then execute ``callback(**kwargs)``. + +The most direct migration path would be to use the ``DeadlineReference.DAGRUN_LOGICAL_DATE`` reference, but note that +the major change is that the Deadline's callback will execute "immediately" (within ``scheduler_heartbeat_sec`` of the +calculated expiation time) and not wait until the Dag finishes first. + +Equivalent Example Dags +----------------------- + +Below is a Dag using a 1-hour SLA, followed by an equivalent Dag using Deadline Alerts. + +SLA Example +^^^^^^^^^^^ + +.. code-block:: python + + with DAG( + "minimal_sla_example", + default_args={"sla": timedelta(hours=1)}, + sla_miss_callback=SlackWebhookNotifier( + text="SLA missed for {{ dag.dag_id }}", + ), + ): + BashOperator(task_id="long_task", bash_command="sleep 3600") + +Deadlines Example +^^^^^^^^^^^^^^^^^ + +.. code-block:: python + + with DAG( + "minimal_deadline_example", + deadline=DeadlineAlert( + reference=DeadlineReference.DAGRUN_LOGICAL_DATE, + interval=timedelta(hours=1), + callback=AsyncCallback( + SlackWebhookNotifier, + kwargs={ + text: "Deadline missed for {{ dag.dag_id }}", + }, + ), + ), + ): + BashOperator(task_id="long_task", bash_command="sleep 3600") + + +## Further Reading Review Comment: This didn't render correctly as a heading -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: commits-unsubscr...@airflow.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
