无法运行 Airflow 中的任务

Question

每当我尝试运行我的 DAG 时，它都会获得成功状态，但它无法运行任务。虽然运行ning 第一次完美运行

trigger_controller_dag.py:

def conditionally_trigger(context, dag_run_obj):
    c_p = context['params']['condition_param']
    if context['params']['condition_param']:
        dag_run_obj.payload = {'message': context['params']['message']}
        pp.pprint(dag_run_obj.payload)
        return dag_run_obj

dag = DAG(
    dag_id='example_trigger_controller_dag',
    default_args={
        "owner": "airflow",
        "start_date": datetime.utcnow(),
    },
    schedule_interval='@once',
)

trigger = TriggerDagRunOperator(
    task_id='test_trigger_dagrun',
    trigger_dag_id="example_trigger_target_dag",
    python_callable=conditionally_trigger,
    params={'condition_param': True, 'message': 'Hello World'},
    dag=dag,
)

trigger_target_dag.py:

args = {
    'start_date': datetime.utcnow(),
    'owner': 'airflow',
}

dag = DAG(
    dag_id='example_trigger_target_dag',
    default_args=args,
    schedule_interval=None,
)


def run_this_func(ds, **kwargs):
    print("Remotely received value of {} for key=message".
          format(kwargs['dag_run'].conf['message']))


run_this = PythonOperator(
    task_id='run_this',
    provide_context=True,
    python_callable=run_this_func,
    dag=dag,
)

在运行处理 DAG 时出现以下错误， dependency 'Task Instance State' FAILED：任务处于 'success' 状态，这不是执行的有效状态。必须清除任务才能运行

Answer 1

而不是 schedule_interval='@once' 试试 schedule_interval=None.

@once表示只会运行一次。

Answer 2

您的 start_date 两个 DAGS 中的变量都是动态的，可能会导致您的问题 'start_date': datetime.utcnow()。不建议将它们设置为动态启动，这会导致错误。

尝试将其设置为静态开始日期，例如 'start_date': datetime(2019, 5, 29) #year month day

取自Airflow FAQ

We recommend against using dynamic values as start_date, especially datetime.now() as it can be quite confusing. The task is triggered once the period closes, and in theory an @hourly DAG would never get to an hour after now as now() moves along.

关于此的另一个 SO 问题：why dynamic start causes issues

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