I believe this is the current behaviour, the dag must be active when you using event driven and thats what i see at-least event driven meaning. the request your referring is something like new functionality that is like, store the events and process. cc: @vincbeck please correct me. :)

Yeah DAG needs to be active.

thanks for your reponses, if I understand event driven dags should never be paused and if I need to prevent it to run (ex in case of maintenance of a database) I need to block what causes trigger to return event (in case of example_asset_with_watchers I need to stop what create /tmp/test file) ?

Other question, during my tests I guess that one time between the time that dags was paused and the trigger stop whatching for file, the /tmp/test was deleted but no asset event was generated, but since I was not able to find which part of code manage the return of trigger and create the asset event I was not able to push more investigation. Could you tell me where I can find these code ?

I confirm everything that has been said here. example_asset_with_watchers might not be the best example and I might replace with a real world scenario. A paused DAG will never be executed if it receives an event (because it is paused). If you want to emit event -> store event -> process event then you might want to use a queue. It needs to be configured outside of Airflow. You configure you env to be send to a queue of choice and then you, in Airflow, your configure your DAG to be executed whenever a new message lands in the queue. Today only SQS is available (with SqsMessageQueueProvider) as queue provider to be compatible with event driven scheduling but other providers should be soon available.

Other question, during my tests I guess that one time between the time that dags was paused and the trigger stop whatching for file, the /tmp/test was deleted but no asset event was generated, but since I was not able to find which part of code manage the return of trigger and create the asset event I was not able to push more investigation. Could you tell me where I can find these code ?

https://github.com/apache/airflow/blob/main/airflow-core/src/airflow/assets/manager.py#L109

thanks for your response, I've managed to understand what happens when file is delete but no asset_event is created when pausing the dag. In fact, it seems that the asset_trigger link is deleted between the moment trigger yield event and the moment register_asset_change is called due to dag paused.

It may not be considered as a bug since event driven dag should not be paused, but it's limit their usage to handle case when you have the possibility to pause the initial event source or if events doesn't have significant payload and you can wait for the next event/create a dummy event from UI after unpausing

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