Fix: Grid and Graph Rendering Issues in Airflow 3.0 for Dynamic DAGs

[arunangshu01]

Related Issues -

1. closes: Airflow 3.0.2: Airflow Grid UI not rendering. #51955
2. closes: Airflow 3.0.2: Airflow Graph UI not rendering task state colors. #51954

This PR addresses a consistent issue observed during recent tests involving dynamic DAGs in Airflow 3.0. Specifically, when a variable is updated within an ongoing task, the DAG version used for rendering the graph view incorrectly falls back to the initial DAG version instead of the latest one.

As a result, the graph colors are not properly rendered, making it difficult to trace the current state and flow across different stages of the DAG run. This fix ensures that both the grid and graph views correctly reference the latest DAG version (in descending order), improving visibility and debugging during pipeline execution.

Contributors are welcome to review, test, and suggest improvements.

Thank you!

[boring-cyborg]

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[bugraoz93]

Are these related? Maybe we can prevent duplicate work
#53087

[arunangshu01]

@bugraoz93 - Thanks for the comment. I’ll review the PR, pull the changes, and check if the issue I raised has been resolved.

[arunangshu01]

@bugraoz93 - Thank you for resolving the grid issue - I have reviewed the latest main branch as well as your PR, and things are looking good on that front.

I also tested the 3.0.3rc5 pre-release for my dynamic DAG use case. While the grid view now renders properly, I’m still noticing issues with task instance colors in the graph view - they don’t reflect the expected states.

I would be happy to test a newer pre-release once those fixes are in, especially to verify whether the grid and graph color rendering are fully resolved.

If helpful, I’m available for a quick 1:1 call to walk you through the issue (though I won’t be able to share actual code due to organizational confidentiality policies). :)

Thanks again for the prompt fix and ongoing support !

[mpunch1]

Are these related? Maybe we can prevent duplicate work #53087

@bugraoz93 One of the issue is related to that, but for the dynamic DAG when the version changes while the DAG is in running state the new graph is being generated but the state Colour are not rendering as the api is failing

[pierrejeambrun]

@mpunch1 @arunangshu01 can you double check on latest RC (rc5), also can you provide a minimal dummy DAG that reproduces the problem?

[arunangshu01]

from airflow.sdk import DAG
from airflow.providers.standard.operators.python import PythonOperator
from airflow.sdk import Variable
import pendulum
from datetime import timedelta
import time
import ast

default_args = {
    'owner': 'airflow',
    'retries': 5,
    'retry_delay': timedelta(minutes=1),
}

def set_list_variable(**kwargs):
    Variable.set('sample_list', str(list(range(1, 1500))))

def get_list():
    val = Variable.get('sample_list', default='[1]')
    return ast.literal_eval(val) if isinstance(val, str) else val

def iterator_task(i, **kwargs):
    print(f"Processing item {i}, sleeping for 2 seconds")
    time.sleep(2)

def iterator_task1(i, **kwargs):
    print(f"Processing item {i}, sleeping for 2 seconds")
    if isinstance(i, str):
        raise Exception
    time.sleep(2)

def final_task(**kwargs):
    print("All iterator tasks are done.")

with DAG(
    'dynamic_sequential_dag',
    default_args=default_args,
    description='DAG with variable-driven dynamic tasks (classic loop)',
    schedule=None,
    start_date=pendulum.datetime(2023, 1, 1, tz="UTC"),
    catchup=False,
    tags=['example'],
) as dag:

    t1 = PythonOperator(
        task_id='set_list_variable',
        python_callable=set_list_variable,
    )

    t2 = PythonOperator(
        task_id='task_2',
        python_callable=iterator_task,
        op_args=[2],
    )

    tasks = []
    for i in eval(Variable.get('sample_list', default='["dummy"]')):
        task = PythonOperator(
            task_id=f'iterator_task_{i}',
            python_callable=iterator_task1,
            op_args=[i],
            retries=5,
        )
        tasks.append(task)

    t3 = PythonOperator(
        task_id='final_task',
        python_callable=final_task,
    )

    t1 >> t2 >> tasks >> t3

@bugraoz93, @pierrejeambrun - Here you go with a sample dag code.

[bugraoz93]

Are these related? Maybe we can prevent duplicate work #53087

@bugraoz93 One of the issue is related to that, but for the dynamic DAG when the version changes while the DAG is in running state the new graph is being generated but the state Colour are not rendering as the api is failing

I just followed up. Thanks to Pierre! :) Also, thanks for your PR!

@bugraoz93 - Thank you for resolving the grid issue - I have reviewed the latest main branch as well as your PR, and things are looking good on that front.

Thanks for example!

[bugraoz93]

Is this DAG failing?

[mpunch1]

Is this DAG failing?

yes the DAG either fails(even after the retries) or it get parsed before reaching the task and the new DAG is graph is rendered but the task state colors are not reflected because the api fails.
The error i have mentioned in the #53087
I see that the routes have been restructured and there is significant change in grid routes queries will give it a try with latest main code.

Thanks @bugraoz93

[bugraoz93]

Is this DAG failing?

yes the DAG either fails(even after the retries) or it get parsed before reaching the task and the new DAG is graph is rendered but the task state colors are not reflected because the api fails.
The error i have mentioned in the #53087
I see that the routes have been restructured and there is significant change in grid routes queries will give it a try with latest main code.

Thanks @bugraoz93

Thanks that would be amazing @mpunch1!

[pierrejeambrun]

Thanks @arunangshu01 for the reproducible example.

cc: @dstandish This might be related to the recent grid optimization / refactoring.

[pierrejeambrun]

I see that the routes have been restructured and there is significant change in grid routes queries will give it a try with latest main code.

Let us know your findings, thanks