Source code for airflow.operators.latest_only
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"""Contains an operator to run downstream tasks only for the latest scheduled DagRun."""
from __future__ import annotations
from typing import TYPE_CHECKING, Iterable
import pendulum
from airflow.operators.branch import BaseBranchOperator
if TYPE_CHECKING:
from airflow.models import DAG, DagRun
from airflow.utils.context import Context
[docs]class LatestOnlyOperator(BaseBranchOperator):
"""
Skip tasks that are not running during the most recent schedule interval.
If the task is run outside the latest schedule interval (i.e. external_trigger),
all directly downstream tasks will be skipped.
Note that downstream tasks are never skipped if the given DAG_Run is
marked as externally triggered.
"""
[docs] ui_color = "#e9ffdb" # nyanza
[docs] def choose_branch(self, context: Context) -> str | Iterable[str]:
# If the DAG Run is externally triggered, then return without
# skipping downstream tasks
dag_run: DagRun = context["dag_run"] # type: ignore[assignment]
if dag_run.external_trigger:
self.log.info("Externally triggered DAG_Run: allowing execution to proceed.")
return list(context["task"].get_direct_relative_ids(upstream=False))
dag: DAG = context["dag"]
next_info = dag.next_dagrun_info(dag.get_run_data_interval(dag_run), restricted=False)
now = pendulum.now("UTC")
if next_info is None:
self.log.info("Last scheduled execution: allowing execution to proceed.")
return list(context["task"].get_direct_relative_ids(upstream=False))
left_window, right_window = next_info.data_interval
self.log.info(
"Checking latest only with left_window: %s right_window: %s now: %s",
left_window,
right_window,
now,
)
if not left_window < now <= right_window:
self.log.info("Not latest execution, skipping downstream.")
# we return an empty list, thus the parent BaseBranchOperator
# won't exclude any downstream tasks from skipping.
return []
else:
self.log.info("Latest, allowing execution to proceed.")
return list(context["task"].get_direct_relative_ids(upstream=False))