气流电子邮件操作员成功/失败

Question

I'm currently working on a DAG that will email a list of users whether the DAG has completed successfully or has failed. I am trying to have the flow of the DAG look like the example here:

from datetime import datetime
from airflow import DAG
from airflow.operators.python_operator import PythonOperator
from airflow.operators.email_operator import EmailOperator

def print_hello():
    return 'Hello world!'

default_args = {
        'owner': 'peter',
        'start_date':datetime(2018,8,11),
}

dag = DAG('hello_world', description='Simple tutorial DAG',
          schedule_interval='* * * * *',
          default_args = default_args, catchup=False)

hello_operator = PythonOperator(task_id='hello_task', python_callable=print_hello, dag=dag)

email_success = EmailOperator(
        task_id='send_email',
        to='to@gmail.com',
        subject='Airflow Alert Success',
        html_content=""" <h3>Email Test Success</h3> """,
        dag=dag
)

email_failure = EmailOperator(
        task_id='send_email',
        to='to@gmail.com',
        subject='Airflow Alert Failure',
        html_content=""" <h3>Email Test Failed</h3> """,
        dag=dag
)

hello_operator.set_downstream(email_success,email_failure)

Is there a built in operator that I can use with airflow to decide whether the email_success operator is sent when the DAG completes or if email_failure operator is executed when the DAG fails for any reason?

Thank you

Answer 1

I ran into this question while searching for how to get Airflow to email me upon success.

Airflow is able to email on failure or retry with the following in default_args.

default_args = {
    'email': ['some_email@gmail.com'],
    'email_on_failure': True,
    'email_on_retry': True,
    'retries': 1,
    'retry_delay': timedelta(minutes=5)
 }

This should help with part of your question regarding failure, and you could use your 'email_success' EmailOperator as the last task in your sequence.

Answer 2

I think you can can use the BranchOperator to decide to send an email on Failure or Success. I have the same scenario whereas I send an email on failure and just ran a DummyOperator if success.

You can check this related question about branchOperator How does Airflow's BranchPythonOperator work?

Answer 3

I guess what you are looking for are Trigger Rules

You could set the trigger rule for the email that should be sent when nothing fails to all_success (default) and the trigger rule for the email that should be sent on failure to all_failed .