TaskFlow DAGs don't register implicitly

[BasPH]

Apache Airflow version

2.5.0

What happened

TaskFlow @dags don't register without explicitly calling the function that defines it.

What you think should happen instead

My understanding is that since Airflow 2.4 DAGs don't require explicit registration as a global object anymore (this is also mentioned in https://airflow.apache.org/docs/apache-airflow/stable/tutorial/taskflow.html#instantiate-a-dag). However, this seems to only be true for the classic style and not for taskflow style DAGs.

How to reproduce

import datetime

from airflow import DAG
from airflow.decorators import dag, task
from airflow.operators.empty import EmptyOperator

with DAG(dag_id="no_global_dag_registration", start_date=datetime.datetime(2023, 1, 1), schedule=None):
    EmptyOperator(task_id="test")


@dag(start_date=datetime.datetime(2023, 1, 1), schedule=None)
def no_global_dag_registration_taskflow():
    @task
    def test():
        pass

My understanding both styles should register the DAG, however only DAG "no_global_dag_registration" does. For the taskflow-style DAG I have to call no_global_dag_registration_taskflow() for it to register.

Operating System

varying

Versions of Apache Airflow Providers

No response

Deployment

Other

Deployment details

No response

Anything else

No response

Are you willing to submit PR?

• Yes I am willing to submit a PR!

Code of Conduct

• I agree to follow this project's Code of Conduct

[Taragolis]

Maybe doc has not clear description, but it actually mentioned how it work.

Changed in version 2.4: It’s no longer required to “register” the DAG
into a global variable for Airflow to be able to detect the dag if that DAG 
is used inside a with block, or if it is the result of a @dag decorated function.

My understanding of differences

# Before Airflow 2.4
dag = decorated_function()
# or
_ = decorated_function()

with DAG(...) as daaaag:
    ...


# Since Airflow 2.4
decorated_function()

with DAG(...):
    ...

[BasPH]

Doh! I'll make a PR for the docs to clarify this.