How to set trigger_rule on specific tasks in Airflow

Question

I would like to set trigger rules on specific tasks.

For instance, if i have the following dependencies in my dag:

task_init >> task_1 >> task_2

• task_init needs to be ok to run task_1
• task_2 can run only if task_init is ok but does not pay attention to task_2

How can i do it?

Answer 1

You don't need trigger rules for what you're describing:

task_init >> [task_1, task_2]

By default, tasks in Airflow run if the previous task completed successfully. So in this code, task_init starts, and tasks task_1 and task_2 only start after task_init completed successfully. A list ( [] ) can be used to group tasks together and dependencies can be set between a single task and a list of tasks.

You can also view this in the Airflow Graph View:

Read more about task dependencies here:

• https://airflow.apache.org/docs/apache-airflow/stable/concepts/dags.html#task-dependencies
• https://www.astronomer.io/guides/managing-dependencies

Answer 2

task_init >> task_1 >> task_2
task_init >> task_2

This will resolve the problem. More information can be found here https://stackoverflow.com/a/66866925