[GitHub] [airflow] jhtimmins commented on a change in pull request #17552: AIP 39: Documentation

[GitBox <gi...@apache.org>]

jhtimmins commented on a change in pull request #17552:
URL: https://github.com/apache/airflow/pull/17552#discussion_r697792179



##########
File path: airflow/example_dags/example_workday_timetable.py
##########
@@ -0,0 +1,92 @@
+#
+# 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.
+
+"""Example DAG demostrating how to implement a custom timetable for a DAG."""
+
+# [START howto_timetable]
+from datetime import timedelta
+from typing import Optional
+
+from pendulum import Date, DateTime, Time, timezone
+
+from airflow import DAG
+from airflow.operators.dummy import DummyOperator
+from airflow.timetables.base import DagRunInfo, DataInterval, TimeRestriction, Timetable
+
+UTC = timezone("UTC")
+
+
+class AfterWorkdayTimetable(Timetable):
+
+    # [START howto_timetable_infer_data_interval]
+    def infer_data_interval(self, run_after: DateTime) -> DataInterval:
+        weekday = run_after.weekday()
+        if weekday in (0, 6):  # Monday and Sunday -- interval is last Friday.
+            days_since_friday = (run_after.weekday() - 4) % 7
+            delta = timedelta(days=days_since_friday)
+        else:  # Otherwise the interval is yesterday.
+            delta = timedelta(days=1)
+        start = DateTime.combine((run_after - delta).date(), Time.min).replace(tzinfo=UTC)
+        return DataInterval(start=start, end=(start + timedelta(days=1)))
+
+    # [END howto_timetable_infer_data_interval]
+
+    # [START howto_timetable_next_dagrun_info]
+    def next_dagrun_info(
+        self,
+        last_automated_dagrun: Optional[DateTime],
+        restriction: TimeRestriction,
+    ) -> Optional[DagRunInfo]:
+        if last_automated_dagrun is not None:
+            # There was a previous run on the regular schedule.
+            # last_automated_dagrun os the last run's logical date.
+            weekday = last_automated_dagrun.weekday()
+            if 0 <= weekday < 4:  # Monday through Thursday -- next is tomorrow.
+                delta = timedelta(days=1)
+            else:  # Week is ending -- skip to next Monday.
+                delta = timedelta(days=(7 - weekday))
+            start = DateTime.combine((last_automated_dagrun + delta).date(), Time.min)

Review comment:
       Reminder @uranusjr that there is a bug in this example. The next interval should start at a delta from the start of the incoming dagrun, not the dagrun execution time.




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