topic Alert scheduling - cron expression not working as expected in Alerting

Alert scheduling - cron expression not working as expected

mattbg — Tue, 17 Nov 2020 13:41:23 GMT

I'm trying to schedule a particular alert to run on the first Monday of each fiscal quarter using this cron expression:

0 9 1-7 2,5,8,11 1

My reading of this is "9:00am on the first Monday of Feb, May, Aug, and Nov".

However, with this month being November (11) for some reason it is running it every Monday. It unexpectedly ran this past Mon Nov 16th and has a "next scheduled time" of Mon Nov 23rd. Given the day-of-month restriction (3rd field) of 1-7 I would not have expected this to happen.

Any advice appreciated. Splunk Enterprise 8.0.6. Thanks.

Re: Alert scheduling - cron expression not working as expected

richgalloway — Tue, 17 Nov 2020 14:28:40 GMT

According to crontab.guru, that cron expression means "At 09:00 on every day-of-month from 1 through 7 and on Monday in February, May, August, and November.” (https://crontab.guru/#0_9_1-7_2,5,8,11_1)

That the alert ran on the 16th seems like a bug to me. I suggest opening a support request with Splunk.

Re: Alert scheduling - cron expression not working as expected

teunlaan — Fri, 20 Nov 2020 08:22:14 GMT

It's not a bug, crontab.guru gives the correct explenation.

"At 09:00 on every day-of-month from 1 through 7 and on Monday in February, May, August, and November.”

the 16th was a Monday

Re: Alert scheduling - cron expression not working as expected

mattbg — Tue, 24 Nov 2020 17:23:33 GMT

I ended up using this cron expression to run on monthdays 1-7 regardless of the weekday:

0 9 1-7 2,5,8,11 *

...and then filtering my results so that I only got results on Mondays:

… | eval today_weekday=strftime(now(), “%w”) | where today_weekday=1

I couldn't use a time range filter because the underlying data can be generated at any time and the alert just sends the most recent results that exist at the start of the quarter.