max_active_runs ignored with externally triggered DAGs

[easthy-alterpost]

Apache Airflow version

2.1.4

Operating System

Amazon Linux 2 AMI

Versions of Apache Airflow Providers

No response

Deployment

Other

Deployment details

Cloudformation template based on https://github.com/villasv/aws-airflow-stack/blob/v2/aws/cloud-formation-template.yml

What happened

DAG can have multiple active runs despite of max_active_runs set to 1 when it is triggered externally from TriggerDagRunOperator

What you expected to happen

If DAG has max_active_runs = 1 it should never be started more than once

How to reproduce

DAG #1

with DAG('dag_1',
                default_args=default_args,
                max_active_runs=1,
                start_date=datetime(2021, 11, 1),
                schedule_interval="* * * * *",
                dagrun_timeout=timedelta(minutes=1),
                catchup=False) as dag:

    TriggerDagRunOperator(task_id='trigger_dag_2',
                                                          trigger_dag_id='dag_2')

DAG #2

from airflow.operators.bash import BashOperator

with DAG('dag_2',
                default_args=default_args,
                max_active_runs=1,
                start_date=datetime(2021, 11, 1),
                schedule_interval=None,
                dagrun_timeout=timedelta(minutes=10),
                catchup=False) as dag:

    BashOperator(
        task_id="dag_keeper",
        bash_command="sleep 5m"
    )

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

[bhavaniravi]

Duplicate of #18583
This PR #18226 have fixed this