Pipelines: Referenced Cron format docs misleads

[consideRatio]

Summary

I was led to believe from kubeflow/pipelines frontend that I could and should specify a Cron expression with only five parts, as described here, but in reality six parts should be used.

Investigation

kubeflow/pipelines is currently using robfig/cron (v2) to parse cron specifications provided in ScheduledWorkflows, but not the latest version robfig/cron/v3 that has a breaking change: seconds are now excluded by default in the cron job specification.

In the kubeflow/pipelines frontend though, we reference the latest versions documentation:

https://github.com/kubeflow/pipelines/blob/b72de99f0ed5536f5fb6697d9b8d60db6fc271fe/frontend/src/components/Trigger.tsx#L289-L295

This latest version of the robfig/cron documentation excludes the seconds field that we still use as we still use the old v2 version of robfig/cron to parse the expression.

I don't know how to make a fix to point to the v2 version of robfig/cron though, because GoDoc
doesn't seem to support that.

Related

Issue #2318 suggest the use of the v3 version.

[consideRatio]

I investigated the situation in this Go playground that left me a lot wiser about the issue overall. See https://play.golang.org/p/O6-WnL8343u.

I'd love for someone to suggest a course of action that is suitable for this project. Some preliminary ideas in my mind are:

1. We could update the frontend to not point to the new cron parsing scheme, but the current used cron parsing scheme.
2. We could change the cron expression parsing behavior, for all or for specifically new recurring jobs, by updating to use robfig/cron/v3 and ensuring old jobs behave the same still.
3. Something else

[consideRatio]

/cc: @nikenano

[discordianfish]

I'm quite disappointed that my issue just was closed without discussion..

[shotarok]

I had the same confusion. The link explains the standard format but the default value is for the cron format used by the Quartz Scheduler.

I'm using KFP v0.5.1 with AI Platform Pipeline. It looks like both formats work. So how about changing the default value to follow the standard format? Or how about changing the link to http://www.quartz-scheduler.org/documentation/quartz-2.3.0/tutorials/tutorial-lesson-06.html?

[rmgogogo]

I'm quite disappointed that my issue just was closed without discussion..

Sorry I thought you can reopen it while I missed your reply
https://github.com/kubeflow/pipelines/issues/2318

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[consideRatio]

@NikeNano was this something you worked on btw? Is it resolved and ready for closure?

[NikeNano]

@NikeNano was this something you worked on btw? Is it resolved and ready for closure?

Hi, as far as I know this is not resolved. I am currently working on the CronJobScheduler so will also look in to this! Thanks for the bump!

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[NikeNano]

Will fix this after https://github.com/kubeflow/pipelines/pull/4641 is merged.