Allow for scheduling flows every nth business day

Current behavior

We would like to schedule a flow to run every fourth business day - as @jcrist has already confirmed, there is no way right to now to implement this currently using the available prefect scheduling utilities (Interval clocks + filters + adjustments … ).

Our use-case is we need to consume certain financial reports that get published on a 4th business day lag every month, I would assume others working in the financial industry might face a similar problem, where they need to act on the data as soon as it is made available …

Proposed behavior

The simple workaround is to have a custom is_nth_business_day filter which should resolve this.

Example

        flow.schedule = Schedule(
            # fire every day
            clocks=[IntervalClock(days=1)],
            # but only on the 4th business day
            filters=[
                is_nth_business_day(4),
            ],
        )

[marwan116]

Sorry @jcrist - just reading this, I was asking for the 4th business day of every month … so I suppose I could make use of DatesClock as @cicdw is suggesting … (I am sorry I wasn’t aware of this option - should have read the documentation)

[madkinsz]

There is a lightweight way of achieving this today, and a way we could make it more configurable in the future:

I don’t see how this gets every 4th business day, but maybe I’m misunderstanding the request. If the request was for the 4th business day of every month or of every week, I see how that would work, but not every 4th business day.

Just to jot down the thought while I have it, you could probably use the pandas time series handling to generate the list of dates to pass into the DatesClock which offloads the complex date handling to something built for it but prevents us from having to require it.