DAG Serialization doesn't have mro context for Operators

[bhavaniravi]

Apache Airflow version

2.1.3

Operating System

Debian GNU/Linux 10 (buster)

Versions of Apache Airflow Providers

No response

Deployment

Other

Deployment details

Breeze

What happened

Dag serialization loses the parent class context and MRO for the operators. This was the root cause of #18492
We cannot use isinstance(task, <OperatorClass>) after deserializing DAG

What you expected to happen

No response

How to reproduce

Example DAG

from airflow import DAG
from airflow.operators.python import PythonOperator
from airflow.utils.dates import days_ago
from datetime import datetime

DAG_NAME = 'example_subdag_operator'

args = {
    'owner': 'airflow',
}
with DAG(
    dag_id=DAG_NAME, default_args=args, start_date=days_ago(2), schedule_interval="@once", tags=['example']
) as dag:

    tn = PythonOperator(
            task_id=f'simple_python',
            python_callable=simple_python,  # make sure you don't include the () of the function
            provide_context=True,
    )

Serialization script

import datetime
from airflow.operators.dummy import DummyOperator
from airflow.models import DAG
from airflow.serialization.serialized_objects import SerializedDAG
import rich

from example_subdag import dag, PythonOperator, CustomPythonOperator

task = dag.get_task("simple_python")
print ((isinstance(task, PythonOperator)))


output_dict = SerializedDAG.to_dict(dag)
new_dag = SerializedDAG.from_dict(output_dict)


task = new_dag.get_task("simple_python")
print ((isinstance(task, PythonOperator))) # Returns false

Anything else

Related issues

#18492

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

[mik-laj]

I think it is expected. We don't want to load the user code on the web server.

If we need to do some MRO check, we should do it during serialization. We are already doing something similar for the DummyOperator.

airflow/airflow/serialization/serialized_objects.py

Lines 483 to 484 in b0442f3

	# Used to determine if an Operator is inherited from DummyOperator
	serialize_op['_is_dummy'] = op.inherits_from_dummy_operator

[ashb]

Yeah -- this is by design. A serialized DAG is not the same as a real dag.

[ashb]

(The fix is as mik-laj suggests, but we don't need this issue as we already have #18492 )