Apache Airflow Sample DAG file

sample_dag.py

from datetime import datetime, timedelta
from textwrap import dedent

from airflow import DAG
from airflow.operators.bash import BashOperator
from airflow.operators.python import PythonOperator
from airflow.decorators import task

# define default arguments for operators.
default_args = {
    "retries": 1,
    "retry_delay": timedelta(minutes=5),
}

# instantiate a DAG.
with DAG(
    "sample_dag",
    default_args=default_args,
    description="A sample DAG",
    schedule_interval=timedelta(days=1),
    start_date=datetime(2022, 6, 1),
    end_date=datetime(2022, 12, 31),
    catchup=False,
    tags=["sample"],
) as dag:

    # add documentation to a DAG.
    dag.doc_md = __doc__
    dag.doc_md = dedent(
        """This is a sample DAG."""
    )

    # task definitions
    # define the task of bash operator.
    bash_task = BashOperator(
        task_id="print_date",
        bash_command="date",
    )
    bash_task.doc_md = dedent(
        """This is a sample bash task: print_date."""
    )

    # define the task of bash operator with jinja template.
    templated_command = dedent(
        """
        {% for i in range(5) %}
            echo "{{ ds }}"
            echo "{{ macros.ds_add(ds, 7)}}"
        {% endfor %}
        """
    )

    bash_task_with_jinja = BashOperator(
        task_id="print_template",
        bash_command=templated_command,
    )
    bash_task_with_jinja.doc_md = dedent(
        """This is a sample bash task: print_template."""
    )

    # define the task of python operator.
    def print_version() -> None:
        import sys
        print(sys.version)
        return None

    python_task = PythonOperator(
        task_id="print_python_version",
        python_callable=print_version,
    )
    python_task.doc_md = dedent(
        """This is a sample python task: print_python_version."""
    )

    # define the task of python operator using decorator.
    @task(task_id="print_arg")
    def print_arg(arg: str) -> None:
        print(arg)
        return None

    python_task_using_decorator = print_arg("sample.")
    python_task_using_decorator.doc_md = dedent(
        """This is a sample python task: print_arg."""
    )

    # setting up dependencies.
    bash_task >> bash_task_with_jinja >> python_task >> python_task_using_decorator  # noqa: E501