SLA misses and notifications in Apache Airflow - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding SLA Misses in Airflow

What happens in Airflow when a task misses its SLA?

A Airflow immediately stops the entire DAG run and marks it as failed.

B Airflow triggers an SLA miss callback and logs the event but does not stop the DAG run.

C Airflow retries the task automatically regardless of retry settings.

D Airflow ignores the SLA miss and continues without any notification.

💡 Hint

Think about how Airflow handles SLA misses without interrupting the workflow.

When a task misses its SLA, Airflow triggers an SLA miss callback and logs the event. It does not stop the DAG run or retry the task automatically. This allows the workflow to continue while notifying about the delay.

💻 Command Output

intermediate

SLA Miss Notification Email Content

Given the following SLA miss callback function in Airflow, what will be the subject line of the notification email sent?

def sla_miss_callback(dag, task_list, blocking_task_list, slas, blocking_tis):
    return f"SLA Miss Alert: DAG {dag.dag_id} missed SLA for tasks {', '.join(task_list)}"

# Assume dag.dag_id = 'data_pipeline', task_list = ['task1', 'task2']

A SLA Miss Alert: DAG data_pipeline missed SLA for tasks task1, task2

B Alert: SLA missed for data_pipeline tasks task1 and task2

C SLA Missed: data_pipeline task1 task2

D Notification: SLA miss detected in DAG data_pipeline

💡 Hint

Look carefully at the string formatting in the callback function.

The callback function returns a formatted string with the DAG ID and the list of tasks that missed the SLA, joined by commas. This exact string is used as the email subject.

❓ Configuration

advanced

Configuring SLA Miss Email Notifications

Which Airflow configuration setting must be enabled to send email notifications on SLA misses?

A sla_miss_callback must be set and email backend configured

B send_sla_notifications = True in airflow.cfg

C email_on_sla_miss = True in DAG definition

D enable_sla_miss_email = True in airflow.cfg

💡 Hint

Think about what is required beyond just a config flag to send emails.

Airflow requires a defined sla_miss_callback function and a properly configured email backend to send SLA miss notifications. There is no direct config flag like 'enable_sla_miss_email'.

❓ Troubleshoot

advanced

Troubleshooting Missing SLA Notifications

You configured SLA miss notifications in Airflow, but no emails are received when SLAs are missed. What is the most likely cause?

A The SMTP server settings in airflow.cfg are incorrect or missing.

B The DAG has no SLA defined on any tasks.

C The SLA miss callback function is not defined or not assigned in the DAG.

D All of the above.

💡 Hint

Consider all parts needed for SLA notifications to work.

Missing SLA notifications can be caused by no SLA defined, missing callback function, or incorrect email server settings. All these must be correctly set for notifications to work.

🔀 Workflow

expert

SLA Miss Handling Workflow in Airflow

Order the steps Airflow takes when a task misses its SLA.

A 1,3,2,4

B 1,2,4,3

C 1,2,3,4

D 2,1,3,4

💡 Hint

Think about detection, callback, notification, and workflow continuation order.

First, Airflow detects the SLA miss, then triggers the callback, which sends notifications or logs the event, and finally the DAG run continues without stopping.