Write the DAGs

In this chapter, we will learn how to write the DAGs. We will use some of the fundamental Airflow concepts we learned to create these pipelines.

Basics of writing a DAG

Airflow uses Python to define DAGs. A DAG file is nothing but a standard Python file.

To define a DAG, typically, there are five steps:

1. Import Python modules
2. Define default args
   • These args will get passed on to each Operator/Sensor
   • Args can be overridden on a per-task basis during Operator/Sensor initialization
3. Instantiate DAG / Create a DAG object
4. Define tasks
   • A task can be an instance of an Operator or a Sensor
5. Define task sequence and dependencies

Let's continue and write our first DAG.