[GitHub] [airflow] XD-DENG commented on a change in pull request #4291: [AIRFLOW-1488] Add the TriggeredDagRunSensor operator

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

XD-DENG commented on a change in pull request #4291: [AIRFLOW-1488] Add the TriggeredDagRunSensor operator
URL: https://github.com/apache/airflow/pull/4291#discussion_r300197351
 
 

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 File path: airflow/contrib/sensors/triggered_dagrun_sensor.py
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 @@ -0,0 +1,72 @@
+# -*- coding: utf-8 -*-
+#
+# Licensed 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.
+from airflow.exceptions import AirflowException
+from airflow.utils import db
+from airflow.utils.state import State
+from airflow.utils.decorators import apply_defaults
+from airflow.utils.trigger_rule import TriggerRule
+from airflow.models import DagRun
+from airflow.sensors.base_sensor_operator import BaseSensorOperator
+
+
+class TriggeredDagRunSensor(BaseSensorOperator):
+    """
+    Waits for triggered DAG run(s) to complete and checks status.
+
+    :param trigger_task_id: The id of the task that triggered the dags
+        and returns a list of dagrun ids to monitor.
+    :type trigger_task_id: str
+    :param sensor_rule: criteria for success after dagruns complete.
+        Default is ``TriggerRule.ONE_SUCCESS``
+    :type sensor_rule: str
+    """
+    @apply_defaults
+    def __init__(
+            self,
+            trigger_task_id,
+            sensor_rule=None,
+            *args, **kwargs):
+        super(TriggeredDagRunSensor, self).__init__(*args, **kwargs)
+        self.sensor_rule = sensor_rule or TriggerRule.ONE_SUCCESS
+        self.trigger_task_id = trigger_task_id
+
+    def poke(self, context):
+        with db.create_session() as session:
+            runcount = 0
+            ti = context['ti']
+            dagrun_ids = ti.xcom_pull(task_ids=self.trigger_task_id)
+            if dagrun_ids:
+                ids = dagrun_ids[:2]
+                ids = ids + ['...'] if len(dagrun_ids) > 2 else ids
+                self.log.info('Poking for %s', ','.join(ids))
+                runcount = session.query(DagRun).filter(
+                    DagRun.run_id.in_(dagrun_ids),
+                    DagRun.state == State.RUNNING,
+                ).count()
+            else:
+                raise AirflowException("No dagrun ids returned by '{}'".format(
+                    self.trigger_task_id))
+            self.log.info('runcount=%s', runcount)
+            if runcount == 0:
+                successcount = session.query(DagRun).filter(
+                    DagRun.run_id.in_(dagrun_ids),
+                    DagRun.state == State.SUCCESS,
+                ).count()
+                if self.sensor_rule == TriggerRule.ONE_SUCCESS:
+                    if successcount == 0:
+                        raise AirflowException('No dagruns completed successfully.')
+                else:
+                    raise AirflowException("sensor rule '{}' is not supported".format(
+                        self.sensor_rule))
 
 Review comment:
   Thanks. I would like to invite other committers to shed some light on this, and leave the decision to them, in case I missed/misunderstood any of your points.
   
   @ashb @mik-laj @kaxil @feng-tao May you guys have a look at this and advise? Thanks.

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