Does anyone know how to schedule something in prefect based on an rruleset? According to the docs [1] and source code [2] the

RRuleSchedule

only takes a "rrule string". It seems easy to convert a single rrule to a string, but as far as I can tell there is no standard implementation to convert an rrule set into an rrule string [3]. Any ideas? [1] https://docs.prefect.io/api-ref/orion/schemas/schedules/#prefect.orion.schemas.schedules.RRuleSchedule [2] https://github.com/PrefectHQ/prefect/blob/main/src/prefect/orion/schemas/schedules.py#L322 [3] https://github.com/dateutil/dateutil/issues/856

Hey @David Cupp I haven't tested out the RRuleSchedules too much myself yet but these are some example strings from their docs https://dateutil.readthedocs.io/en/stable/rrule.html#rrulestr-examples

Sure, but

rrulestr()

converts from an "rrule string" to an

rruleset

(as necessary). I need the reverse of that operation. As far as I can tell, there is nothing here that can convert from the rruleset python object to an rrule string.

Here are some examples: https://github.com/anna-geller/prefect-deployment-patterns/blob/main/schedules/rrule.bash

Thanks, but those are examples for people who already have an rrule string. I have an "rrule set" which is a python object in the

dateutil

library: https://dateutil.readthedocs.io/en/stable/rrule.html#rruleset-examples I'm confident I know what do to once I have an rrule string, but getting to the string from the rrule set (without writing code that is too hacky) is the challenge.

@David Cupp what problem are you trying to solve on a high level? can you explain what kind of schedule would you like to attach to your deployment?

At a very high level, I'm trying to integrate our proprietary system (or prorprietary representations of a schedule) with Prefect (or prefects notion of a schedule). We have multiple types of schedule definitions. The one that inspired my question here today is the one that our customers can edit in our UI, and which is stored in a database. Each of these schedules is implemented as a set of

ProprietaryConfig

objects. So this is not a case where I personally have a schedule in mind, and need help manually writing an rrule string for it. This is about writing a robust, stable conversion. We already have code that maps from

List[ProprietaryConfig]

-->

dateutil.rruleset

(our existing scheduler uses the rruleset object directly) so Prefect's

RRuleSchedule

seems like the best fit. But

RRuleSchedule

takes a "rrule string", so as far as I know my options are (from best to worst): 1. find some code that can convert

dateutil.rruleset

--> "rrule string" 2. find some code that can convert

List[dateutil.rrule]

--> "rrule string" 3. implement

List[PrioprietaryConfig]

--> "rrule string" 4. find out that we can use multiple

RRuleSchedule

objects or something else that I'm missing. Any of these solutions is possible, but of course I would prefer to avoid doing anything that involves relying on private fields of a python class, or creating our own rrule implmentation.

interesting, perhaps you could start by scheduling your flows directly from your system? would that be an option?

Sure, that is the likely migration plan (migrate DAG execution first). Eventually, I plan to have Prefect Cloud own the scheduler portion.

it doesn't fully answer my question because I would like to find out why rruleset would be necessary. E.g., could you give me examples of schedules that you cannot generate using the current RRuleSchedule object and that would require us to support rruleset?

could you give me examples of schedules that you cannot generate using the current RRuleSchedule object

I'm not trying to claim that Prefect is in any way inadequate, and I think that by supporting an rrule string it technically can handle any type of schedule that we have. My problem is simply an impedance mismatch with the data types (one that I blame python's

dateutil

library for). I'm feeling around for answers because, just like you don't want to roll your own crypto, I don't want to roll my own calendar logic/RFC implementations (unless I have to).

yeah I understand that, but this doesn't motivate a product feature yet, but more e.g. some utility that could help you make that conversion. Have you seen this workaround?

Yeah that's the issue I linked to in my original post here. That is certainly a possibility. The obvious downside is that the moment we rely on an undocumented private member field, we are going to have to be very careful about upgrades to

dateutil

since each one could break our implementation.

Gotcha. If you would be open to contributing something like RRuleSetSchedule, we would certainly review your PR -- might be easier than I think. We just don't have the bandwidth atm to implement this, but this shouldn't stop you from opening a PR -- doesn't hurt for sure

Thanks I will keep that in mind.