Add ability to clear downstream tis in "List Task Instances" view

airflow/www/views.py

@@ -31,7 +31,16 @@
 from collections import defaultdict
 from functools import cached_property, wraps
 from json import JSONDecodeError
-from typing import TYPE_CHECKING, Any, Callable, Collection, Iterator, Mapping, MutableMapping, Sequence
+from typing import (
+    TYPE_CHECKING,
+    Any,
+    Callable,
+    Collection,
+    Iterator,
+    Mapping,
+    MutableMapping,
+    Sequence,
+)
 from urllib.parse import unquote, urljoin, urlsplit
 
 import configupdater
@@ -5657,6 +5666,7 @@ class TaskInstanceModelView(AirflowPrivilegeVerifierModelView):
         "list": "read",
         "delete": "delete",
         "action_clear": "edit",
+        "action_clear_downstream": "edit",
         "action_muldelete": "delete",
         "action_set_running": "edit",
         "action_set_failed": "edit",
@@ -5793,6 +5803,68 @@ def duration_f(self):
         "duration": duration_f,
     }
 
+    def _clear_task_instances(
+        self, task_instances: list[TaskInstance], session: Session, clear_downstream: bool = False
+    ) -> tuple[int, int]:
+        """
+        Clears task instances, optionally including their downstream dependencies.
+
+        :param task_instances: list of TIs to clear
+        :param clear_downstream: should downstream task instances be cleared as well?
+
+        :return: a tuple with:
+            - count of cleared task instances actually selected by the user
+            - count of downstream task instances that were additionally cleared
+        """
+        cleared_tis_count = 0
+        cleared_downstream_tis_count = 0
+
+        # Group TIs by dag id in order to call `get_dag` only once per dag
+        tis_grouped_by_dag_id = itertools.groupby(task_instances, lambda ti: ti.dag_id)
+
+        for dag_id, dag_tis in tis_grouped_by_dag_id:
+            dag = get_airflow_app().dag_bag.get_dag(dag_id)
+
+            tis_to_clear = list(dag_tis)
+            downstream_tis_to_clear = []
+
+            if clear_downstream:
+                tis_to_clear_grouped_by_dag_run = itertools.groupby(tis_to_clear, lambda ti: ti.dag_run)
+
+                for dag_run, dag_run_tis in tis_to_clear_grouped_by_dag_run:
+                    # Determine tasks that are downstream of the cleared TIs and fetch associated TIs
+                    # This has to be run for each dag run because the user may clear different TIs across runs
+                    task_ids_to_clear = [ti.task_id for ti in dag_run_tis]
+
+                    partial_dag = dag.partial_subset(
+                        task_ids_or_regex=task_ids_to_clear, include_downstream=True, include_upstream=False
+                    )
+
+                    downstream_task_ids_to_clear = [
+                        task_id for task_id in partial_dag.task_dict if task_id not in task_ids_to_clear
+                    ]
+
+                    # dag.clear returns TIs when in dry run mode
+                    downstream_tis_to_clear.extend(
+                        dag.clear(
+                            start_date=dag_run.execution_date,
+                            end_date=dag_run.execution_date,
+                            task_ids=downstream_task_ids_to_clear,
+                            include_subdags=False,
+                            include_parentdag=False,
+                            session=session,
+                            dry_run=True,
+                        )
+                    )
+
+            # Once all TIs are fetched, perform the actual clearing
+            models.clear_task_instances(tis=tis_to_clear + downstream_tis_to_clear, session=session, dag=dag)
+
+            cleared_tis_count += len(tis_to_clear)
+            cleared_downstream_tis_count += len(downstream_tis_to_clear)
+
+        return cleared_tis_count, cleared_downstream_tis_count
+
     @action(
         "clear",
         lazy_gettext("Clear"),
@@ -5806,21 +5878,45 @@ def duration_f(self):
     @provide_session
     @action_logging
     def action_clear(self, task_instances, session: Session = NEW_SESSION):
-        """Clears the action."""
+        """Clears an arbitrary number of task instances."""
         try:
-            dag_to_tis = collections.defaultdict(list)
-
-            for ti in task_instances:
-                dag = get_airflow_app().dag_bag.get_dag(ti.dag_id)
-                dag_to_tis[dag].append(ti)
+            count, _ = self._clear_task_instances(
+                task_instances=task_instances, session=session, clear_downstream=False
+            )
+            session.commit()
+            flash(f"{count} task instance{'s have' if count > 1 else ' has'} been cleared")
+        except Exception as e:
+            flash(f'Failed to clear task instances: "{e}"', "error")
 
-            for dag, task_instances_list in dag_to_tis.items():
-                models.clear_task_instances(task_instances_list, session, dag=dag)
+        self.update_redirect()
+        return redirect(self.get_redirect())
 
+    @action(
+        "clear_downstream",
+        lazy_gettext("Clear (including downstream tasks)"),
+        lazy_gettext(
+            "Are you sure you want to clear the state of the selected task"
+            " instance(s) and all their downstream dependencies, and set their dagruns to the QUEUED state?"
+        ),
+        single=False,
+    )
+    @action_has_dag_edit_access
+    @provide_session
+    @action_logging
+    def action_clear_downstream(self, task_instances, session: Session = NEW_SESSION):
+        """Clears an arbitrary number of task instances, including downstream dependencies."""
+        try:
+            selected_ti_count, downstream_ti_count = self._clear_task_instances(
+                task_instances=task_instances, session=session, clear_downstream=True
+            )
             session.commit()
-            flash(f"{len(task_instances)} task instances have been cleared")
+            flash(
+                f"Cleared {selected_ti_count} selected task instance{'s' if selected_ti_count > 1 else ''} "
+                f"and {downstream_ti_count} downstream dependencies"
+            )
         except Exception as e:
             flash(f'Failed to clear task instances: "{e}"', "error")
+
         self.update_redirect()
         return redirect(self.get_redirect())
 

tests/www/views/test_views_tasks.py

@@ -24,6 +24,7 @@
 import urllib.parse
 from getpass import getuser
 
+import pendulum
 import pytest
 import time_machine
 
@@ -32,12 +33,13 @@
 from airflow.models import DAG, DagBag, DagModel, TaskFail, TaskInstance, TaskReschedule, XCom
 from airflow.models.dagcode import DagCode
 from airflow.operators.bash import BashOperator
+from airflow.operators.empty import EmptyOperator
 from airflow.providers.celery.executors.celery_executor import CeleryExecutor
 from airflow.security import permissions
 from airflow.utils import timezone
 from airflow.utils.log.logging_mixin import ExternalLoggingMixin
 from airflow.utils.session import create_session
-from airflow.utils.state import State
+from airflow.utils.state import DagRunState, State
 from airflow.utils.types import DagRunType
 from airflow.www.views import TaskInstanceModelView
 from tests.test_utils.api_connexion_utils import create_user, delete_roles, delete_user
@@ -857,6 +859,63 @@ def test_task_instance_clear(session, request, client_fixture, should_succeed):
     assert state == (State.NONE if should_succeed else initial_state)
 
 
+def test_task_instance_clear_downstream(session, admin_client, dag_maker):
+    """Ensures clearing a task instance clears its downstream dependencies exclusively"""
+    with dag_maker(
+        dag_id="test_dag_id",
+        serialized=True,
+        session=session,
+        start_date=pendulum.DateTime(2023, 1, 1, 0, 0, 0, tzinfo=pendulum.UTC),
+    ):
+        EmptyOperator(task_id="task_1") >> EmptyOperator(task_id="task_2")
+        EmptyOperator(task_id="task_3")
+
+    run1 = dag_maker.create_dagrun(
+        run_id="run_1",
+        state=DagRunState.SUCCESS,
+        run_type=DagRunType.SCHEDULED,
+        execution_date=dag_maker.dag.start_date,
+        start_date=dag_maker.dag.start_date,
+        session=session,
+    )
+
+    run2 = dag_maker.create_dagrun(
+        run_id="run_2",
+        state=DagRunState.SUCCESS,
+        run_type=DagRunType.SCHEDULED,
+        execution_date=dag_maker.dag.start_date.add(days=1),
+        start_date=dag_maker.dag.start_date.add(days=1),
+        session=session,
+    )
+
+    for run in (run1, run2):
+        for ti in run.task_instances:
+            ti.state = State.SUCCESS
+
+    # Clear task_1 from dag run 1
+    run1_ti1 = run1.get_task_instance(task_id="task_1")
+    rowid = _get_appbuilder_pk_string(TaskInstanceModelView, run1_ti1)
+    resp = admin_client.post(
+        "/taskinstance/action_post",
+        data={"action": "clear_downstream", "rowid": rowid},
+        follow_redirects=True,
+    )
+    assert resp.status_code == 200
+
+    # Assert that task_1 and task_2 of dag run 1 are cleared, but task_3 is left untouched
+    run1_ti1.refresh_from_db(session=session)
+    run1_ti2 = run1.get_task_instance(task_id="task_2")
+    run1_ti3 = run1.get_task_instance(task_id="task_3")
+
+    assert run1_ti1.state == State.NONE
+    assert run1_ti2.state == State.NONE
+    assert run1_ti3.state == State.SUCCESS
+
+    # Assert that task_1 of dag run 2 is left untouched
+    run2_ti1 = run2.get_task_instance(task_id="task_1")
+    assert run2_ti1.state == State.SUCCESS
+
+
 def test_task_instance_clear_failure(admin_client):
     rowid = '["12345"]'  # F.A.B. crashes if the rowid is *too* invalid.
     resp = admin_client.post(