Hi all – are there any known issues with Cron clocks? I'm having some difficulty with porting a job out of our old scheduling tool that my team uses to a new one. We have a job that runs every day, every 8 hours starting at 7am. In moving this job to prefect and setting the flow schedule, I'm using a cron schedule that seems to me like it should achieve what I want, and the Prefect UI tells my in plain english that the flow's schedule is correct (within the flow's Overview pane), but then when I look at the scheduled upcoming flows, it doesn't seem to match.

Hi @Sean Talia - let me see take a few minutes to look into this for you.

ok thanks @Jenny!

Hey @Sean Talia, this looks right. Did you have an old schedule? Did you try toggling the schedule bar?

yeah I had an old one that was missing a leading 0 (so it was being scheduled for every 8 minutes 7 minutes past the hour every hour) but then i reregistered with this new one, let me try toggling

Hi @Sean Talia - do you have any schedules set for the flow in the UI? (I.e. through the settings tab on the flow page.)

Yep that looks right. I have an idea that something in the UI might be adding the timezone twice in the upcoming runs tile. Let me check that and get back to you.

One of the things I've had to play around with is the fact that the cron syntax we use in our old tool (Rundeck) is slightly different from what Prefect / croniter expects, so my old crontab was

0 0 7/8 ? * * *

which isn't valid w/ croniter apparently, but I'm pretty sure the new syntax I'm using without the

?

special character is what I want

@Sean Talia - Sorry I don't think it is the UI. But a difference in cron clocks. Can you try:

CronClock(
    cron="0 7/8 * * *",
start_date=pendulum.datetime(
        2021, 7, 1, 0, 0, 0, tz="America/New_York"
    ),
)])

I think that's what I originally had, I'll take a screenshot once I re-register

Note it's one zero at the beginning instead of two

Okay this worked! Sorry that I didn't try this permutation – the problem with my original schedule was that I had 4 `*`'s; so 1.

0 7/8 * * * *

(bad, I know why) 2.

0 0 7/8 * * *

(bad, although the schedule seemed okay when it was spelled out in plain English) 3.

0 7/8 * * *

good

Great! Glad it worked.

So is there then a bug with whatever generates that statement "At 0 minutes past the hour, every 8 hours, starting at 07:00 AM (EDT)"? That seems to have been identical for both

0 0 7/8 * * *

and

0 7/8 * * *

?

Good question! It had me confused for a while too. I’m going to put a ticket in to check.