Airflow如何从代码本身获取每个dag的环境变量

from airflow import DAG
from airflow.models import Variable

dag = DAG(
    'my_dag',
    description='My Airflow DAG',
    schedule_interval='0 0 * * *',
    default_args={
        'email': Variable.get('email'),
        'email_on_failure': Variable.get('email_on_failure'),
    }
)

# 定义任务1
task1 = BashOperator(
    task_id='task1',
    bash_command='echo "Hello Airflow"',
    dag=dag
)

# 定义任务2
task2 = BashOperator(
    task_id='task2',
    bash_command='echo "Hello World"',
    dag=dag
)

task1 >> task2