| # -*- coding: utf-8 -*- |
| # |
| # 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. |
| |
| import os |
| |
| from airflow.exceptions import AirflowException |
| from airflow.models import TaskInstance, DagBag, DagModel, DagRun |
| from airflow.sensors.base_sensor_operator import BaseSensorOperator |
| from airflow.utils.db import provide_session |
| from airflow.utils.decorators import apply_defaults |
| from airflow.utils.state import State |
| |
| |
| class ExternalTaskSensor(BaseSensorOperator): |
| """ |
| Waits for a different DAG or a task in a different DAG to complete for a |
| specific execution_date |
| |
| :param external_dag_id: The dag_id that contains the task you want to |
| wait for |
| :type external_dag_id: str |
| :param external_task_id: The task_id that contains the task you want to |
| wait for. If ``None`` the sensor waits for the DAG |
| :type external_task_id: str |
| :param allowed_states: list of allowed states, default is ``['success']`` |
| :type allowed_states: list |
| :param execution_delta: time difference with the previous execution to |
| look at, the default is the same execution_date as the current task or DAG. |
| For yesterday, use [positive!] datetime.timedelta(days=1). Either |
| execution_delta or execution_date_fn can be passed to |
| ExternalTaskSensor, but not both. |
| :type execution_delta: datetime.timedelta |
| :param execution_date_fn: function that receives the current execution date |
| and returns the desired execution dates to query. Either execution_delta |
| or execution_date_fn can be passed to ExternalTaskSensor, but not both. |
| :type execution_date_fn: callable |
| :param check_existence: Set to `True` to check if the external task exists (when |
| external_task_id is not None) or check if the DAG to wait for exists (when |
| external_task_id is None), and immediately cease waiting if the external task |
| or DAG does not exist (default value: False). |
| :type check_existence: bool |
| """ |
| template_fields = ['external_dag_id', 'external_task_id'] |
| ui_color = '#19647e' |
| |
| @apply_defaults |
| def __init__(self, |
| external_dag_id, |
| external_task_id, |
| allowed_states=None, |
| execution_delta=None, |
| execution_date_fn=None, |
| check_existence=False, |
| *args, |
| **kwargs): |
| super(ExternalTaskSensor, self).__init__(*args, **kwargs) |
| self.allowed_states = allowed_states or [State.SUCCESS] |
| if external_task_id: |
| if not set(self.allowed_states) <= set(State.task_states): |
| raise ValueError( |
| 'Valid values for `allowed_states` ' |
| 'when `external_task_id` is not `None`: {}'.format(State.task_states) |
| ) |
| else: |
| if not set(self.allowed_states) <= set(State.dag_states): |
| raise ValueError( |
| 'Valid values for `allowed_states` ' |
| 'when `external_task_id` is `None`: {}'.format(State.dag_states) |
| ) |
| |
| if execution_delta is not None and execution_date_fn is not None: |
| raise ValueError( |
| 'Only one of `execution_delta` or `execution_date_fn` may ' |
| 'be provided to ExternalTaskSensor; not both.') |
| |
| self.execution_delta = execution_delta |
| self.execution_date_fn = execution_date_fn |
| self.external_dag_id = external_dag_id |
| self.external_task_id = external_task_id |
| self.check_existence = check_existence |
| |
| @provide_session |
| def poke(self, context, session=None): |
| if self.execution_delta: |
| dttm = context['execution_date'] - self.execution_delta |
| elif self.execution_date_fn: |
| dttm = self.execution_date_fn(context['execution_date']) |
| else: |
| dttm = context['execution_date'] |
| |
| dttm_filter = dttm if isinstance(dttm, list) else [dttm] |
| serialized_dttm_filter = ','.join( |
| [datetime.isoformat() for datetime in dttm_filter]) |
| |
| self.log.info( |
| 'Poking for %s.%s on %s ... ', |
| self.external_dag_id, self.external_task_id, serialized_dttm_filter |
| ) |
| |
| DM = DagModel |
| TI = TaskInstance |
| DR = DagRun |
| if self.check_existence: |
| dag_to_wait = session.query(DM).filter( |
| DM.dag_id == self.external_dag_id |
| ).first() |
| |
| if not dag_to_wait: |
| raise AirflowException('The external DAG ' |
| '{} does not exist.'.format(self.external_dag_id)) |
| else: |
| if not os.path.exists(dag_to_wait.fileloc): |
| raise AirflowException('The external DAG ' |
| '{} was deleted.'.format(self.external_dag_id)) |
| |
| if self.external_task_id: |
| refreshed_dag_info = DagBag(dag_to_wait.fileloc).get_dag(self.external_dag_id) |
| if not refreshed_dag_info.has_task(self.external_task_id): |
| raise AirflowException('The external task' |
| '{} in DAG {} does not exist.'.format(self.external_task_id, |
| self.external_dag_id)) |
| |
| if self.external_task_id: |
| count = session.query(TI).filter( |
| TI.dag_id == self.external_dag_id, |
| TI.task_id == self.external_task_id, |
| TI.state.in_(self.allowed_states), |
| TI.execution_date.in_(dttm_filter), |
| ).count() |
| else: |
| count = session.query(DR).filter( |
| DR.dag_id == self.external_dag_id, |
| DR.state.in_(self.allowed_states), |
| DR.execution_date.in_(dttm_filter), |
| ).count() |
| |
| session.commit() |
| return count == len(dttm_filter) |