Use HttpSensor to pause an Airflow DAG until a website is available

This article is a part of my "100 data engineering tutorials in 100 days" challenge. (58/100)

What should I do if I wanted to pause an Airflow DAG until one of my articles gets publishes?

Let’s assume that I have already scheduled publication of the text you are reading right now, and I know the article URL. It is going to be https://mikulskibartosz.name/use-httpsensor-to-wait-for-website

Now, I have to define an HTTP connection in my Airflow connections settings. The connection should point to the root address of my website: https://mikulskibartosz.name.

After that, I add a HttpSensor to my DAG. It is going to use the connection defined earlier and wait until the resource is available:

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sensor = HttpSensor(
    task_id='http_sensor_check',
    http_conn_id='mikulskibartosz_name',
    endpoint='use-httpsensor-to-wait-for-website',
    poke_interval=60,
    dag=dag)

The Airflow DAG will wait until the website returns a status code, which indicates success. When you look at this sensor’s code, you will see that it returns False only when the failure was due to 404 Not Found status. In a case of any other failure, it propagates the exception to Airflow.

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Bartosz Mikulski

Bartosz Mikulski

  • Data/MLOps engineer by day
  • DevRel/copywriter by night
  • Python and data engineering trainer
  • Conference speaker
  • Contributed a chapter to the book "97 Things Every Data Engineer Should Know"
  • Twitter: @mikulskibartosz
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