Trigger rules (all_success, one_success, none_failed) in Apache Airflow - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding all_success trigger rule

In Airflow, what does the all_success trigger rule mean for a task's execution?

A The task runs only if all upstream tasks have succeeded.

B The task runs if at least one upstream task has succeeded.

C The task runs only if no upstream tasks have run.

D The task runs even if some upstream tasks have failed.

💡 Hint

Think about when you want a task to run only after everything before it worked well.

The all_success trigger rule means the task will run only if every upstream task finished successfully. If any upstream task failed or was skipped, this task will not run.

🧠 Conceptual

intermediate

Meaning of one_success trigger rule

What does the one_success trigger rule do in Airflow?

A The task runs only if all upstream tasks have succeeded.

B The task runs if at least one upstream task has succeeded.

C The task runs only if no upstream tasks have succeeded.

D The task runs only if all upstream tasks have failed.

💡 Hint

Imagine you want to continue if any one of the previous tasks worked.

The one_success trigger rule allows the task to run if at least one upstream task succeeded, regardless of others failing or being skipped.

❓ query_result

advanced

Output of task execution with none_failed trigger rule

Given three upstream tasks with statuses: Task A - success, Task B - skipped, Task C - success. If a downstream task uses the none_failed trigger rule, will it run?

A No, because one task was skipped.

B Yes, because all upstream tasks succeeded.

C No, because at least one task succeeded.

D Yes, because no upstream task failed.

💡 Hint

Remember that none_failed means no failures allowed, but skips are okay.

The none_failed trigger rule allows the task to run if no upstream tasks failed. Skipped tasks do not count as failures, so the task will run.

🔧 Debug

advanced

Identify the trigger rule causing a task not to run

A downstream task is set with trigger rule all_success. Upstream tasks have statuses: success, failed, success. Why does the downstream task not run?

A Because <code>all_success</code> ignores failed tasks and runs anyway.

B Because <code>all_success</code> allows running if one task failed.

C Because <code>all_success</code> requires all upstream tasks to succeed, but one failed.

D Because <code>all_success</code> requires at least one task to be skipped.

💡 Hint

Check what all_success means about upstream failures.

The all_success trigger rule means the task runs only if every upstream task succeeded. Since one upstream task failed, the downstream task does not run.

🧠 Conceptual

expert

Choosing the correct trigger rule for conditional continuation

You want a task to run only if none of its upstream tasks failed, but it should run even if some were skipped. Which trigger rule should you use?

A none_failed

B one_success

C all_success

D all_done

💡 Hint

Think about allowing skips but no failures.

The none_failed trigger rule runs the task if no upstream tasks failed. It allows skipped tasks, unlike all_success which requires all to succeed.