How to set a SLA in Airflow?

Question

I would like to set an SLA in a Sensor Operator. The documentation is not too clear about the use of it. So I did a test using the S3KeySensor operator which is looking for a file that does not exist. I set the SLA to 30 seconds, I was hoping to see the record after 30 seconds in the UI - in SLA misses - but it did not happen. What am I doing wrong?

inputsensor = S3KeySensor(
    task_id="check_for_files_in_s3",
    bucket_key="adp/backload/20136585/",
    wildcard_match=True,
    bucket_name="weblogs-raw",
    s3_conn_id="AWS_S3_CENTRAL",
    timeout=120,
    poke_interval=10,
    sla=timedelta(seconds=30),
    dag=dag,
)

inputsensor.set_downstream(next_step)

Answer 1

In hours

"sla": timedelta(hours=2)

In minutes

"sla": timedelta(minutes=120)

Answer 2

According to the documentation SLA represents the timedelta after the schedule period is over. So if your schedule interval is '@daily' and sla=timedelta(hours=1) then Airflow will check for SLA misses at 1:00 AM which is when the schedule period is over plus one hour.