I have a DAG with Task A, Task B, and Task C running one after another.
Is there a way that I can trigger to run just Task B and C from the UI?
From this question: Triggering a task in Airflow with the CLI run command, I know that we can trigger task from CLI.
But I dont know how to do so via the UI
Click on Task B and click CLEAR, this will start running from TASK B and TASK C
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In Apache Airflow, let's say I want to set up a DAG that has 3 tasks.
Task A
Task B
Task C
When the DAG gets scheduled, I want task A to run, followed by Task B (when A completes).
However, I want task C to only run when some external code triggers it (and it shouldn't poll and wait for an external condition to be satisfied; I want it to wait until it receives an external request to start execution, but only if A and B are completed).
I also don't want to create another DAG for task C.
Is this possible? How to set up please? Will it require another task between B and C?
Thanks for any advice on how this can be achieved.
The best way to achieve this is to have two tasks leading into task C, so for example:
A >> [B, x] >> C
Where x is a new task. Then you can set x to be your other trigger condition from somewhere external.
For example if you're waiting for a certain file to be delivered for C to execute, create x as a BranchOperator, and only return C from it if the file exists.
I have 3 dags A, B and C. Dag C should get triggered only after tasks in dag A and B completes. Is there a way to implement this in airflow? I am able to set dependency between dag A and C using Triggerdagrun Operator. But when I try to set dependency between dag B and C, C is getting triggered when either A or B completes.
Can someone please help me in solving this?
I understand that explains external task sensor Operator can be used. But it continuously polls if task in dag A and B is complete which might create performance hit over a period of time.
You could set two more wait-task in your dagc,
then startop >> [wait-daga, wait-dagb] >> dagc.
Below is the link to airflow doc:
https://airflow.apache.org/docs/stable/concepts.html
I have three task in one dag.
Task A run first. Task B runs if task A is successful.
I have Task C which has run after Task B but it is not depend up Task B or Task A success or failure.
Task C needs to no matter what happen to task A and B. However, it needs to run after task A and B is completed.
Any idea ?
To have a task run after other tasks are done, but regardless of the outcome of their execution, set the trigger_rule parameter to all_done like so:
my_task = MyOperator(task_id='my_task',
trigger_rule='all_done'
See the trigger rule documentation for more options
Currently I have a task that run every 5 minute.
what I want is to have that task rerun every time it is completed with 1 minute delay.
what I have in mind is to create multiple task, task A and task B. task B will run after task A complete and vice versa. But not sure how to execute that.
I have found a workaround for my situation. what I do is create loop for task A to run followed by task B with delay in between.
We have many DAGs scheduled to run daily using Airflow. Dependencies has been enabled using ExternalTaskSensor, TriggerDagRunOperator and custom operators
Sample:
Task 1 in DAG A are dependent on task 2 in DAG B
Task 3 in DAG A are dependent on task 4 in DAG C
Task 5 in DAG A are dependent on task 6 in DAG D
...
Task 2 in DAG B are dependent on task 7 in DAG E
Task 4 in DAG B are dependent on task 8 in DAG F
...
While checking Task Instance details in UI, only downstream_task_ids and upstream_task_ids belonging to the same dag are displayed.
How can we see the full lineage of a single task across multiple DAGs to the last available level?
Airflow does not currently (v 1.8.1) have a mechanism for viewing cross-dag dependencies.
At this time if you need a visualization of relationships between tasks, they have to be in the same dag. Potentially a view in a custom plugin could show these dependencies, but the stock UI does not do this.