bug fix: unused arg for batch step --help

[mae5357]

addresses: https://github.com/Netflix/metaflow/issues/1771

issue:

python hello.py batch step --help command was breaking due to wrong type for click.Choice arg.

change:

setting default arg for ubf-context from None to "none" in "batch step" make it compatible with click.Choice()

however, ubf-context is not needed for the "step" function when using aws-batch, so we can safely remove altogether.

[romain-intel]

If you want to keep the functionality, the proper line should read something like:

type=click.Choice(["none", UBF_CONTROL, UBF_TASK]),

I was under the impression that ubf may be used by parallel so may be worth keeping around.

However, no issues either way so feel free to merge when you are happy with it.

[nflx-mf-bot]

Testing[735] @ 4e648627ea6eb6535c0e28e80ce4daf8f1839ee7

[nflx-mf-bot]

Testing[735] @ 4e648627ea6eb6535c0e28e80ce4daf8f1839ee7 had 6 FAILUREs.

[mae5357]

@romain-intel i can revert to if you want https://github.com/Netflix/metaflow/pull/1817/commits/244ff31c9c81ac811ef4b4499c4f819e74a028f3

I was under the impression that ubf may be used by parallel so may be worth keeping around.

fwiw, the step() function this is decorating doesn't take ubf-context as an argument. So there's not a possibility this arg is being used (here).

(edit: i don't have permission to merge)

[saikonen]

Finally had time to test this, and as Romain mentioned, @parallel somewhat depends on the option existing, even if it is not explicitly used. Removing the option completely breaks parallel deco on batch.

Here's a simple test flow for the issue:

from metaflow import step, FlowSpec, parallel

class UBFTest(FlowSpec):
    @step
    def start(self):
        print("Starting 👋")
        self.next(self.process, num_parallel=4)

    @parallel
    @step
    def process(self):
        print(f"processing input: {self.input}")
        self.next(self.join)

    @step
    def join(self, inputs):
        self.next(self.end)

    @step
    def end(self):
        print("Done! 🏁")

if __name__ == "__main__":
    UBFTest()