Throw warning for nested @Task functions

[oliverhu]

TL;DR

Address flyteorg/flyte#3734 that nested Tasks/Workflows is not warned.

Type

• Bug Fix
• Feature
• Plugin

Are all requirements met?

• Code completed
• Smoke tested
• Unit tests added
• Code documentation added
• Any pending items have an associated Issue

Complete description

In order to detect entities that are nested inside @task:

1. During local execution, create a new FlyteContext with LOCAL_TASK_EXECUTION for @task,and LOCAL_WORKFLOW_EXECUTION if it is @workflow.
2. If flyte_entity_call_handler is invoked inside LOCAL_TASK_EXECUTION or TASK_EXECUTION, that means it is called inside @task, warn the users of nested @tasks/@workflows.

Created a helper function is_local_execution() to shorthand the checks.

Tracking Issue

flyteorg/flyte#3734

Follow-up issue

The call() function in remote_callable and reference_entity duplicates and can be replaced with flyte_entity_call_handler as well in the future.

[pingsutw]

Others LGTM

[ByronHsu]

Also, i would prefer to throw exceptions instead of merely logging errors because a nested task is illegal when running remotely?

[ByronHsu]

Just checked with @pingsutw. The nested workflow can actually run fine remotely. To keep backward compatibility, let's just stick with logger.

[pingsutw]

merged, thanks @oliverhu @ByronHsu

[welcome]

Congrats on merging your first pull request! 🎉

[fellhorn]

There seems to be a bug in this implementation as it throws a warning for valid dynamic workflows:

from flytekit import workflow, dynamic, task

@task
def my_task():
    print("foo")

@dynamic
def outer():
    my_task()


@workflow
def workflow(
):
    outer()

if __name__ == "__main__":
    workflow()

prints:

{"asctime": "2023-08-29 11:57:57,824", "name": "flytekit", "levelname": "ERROR", "message": "You are not supposed to nest @Task/@Workflow inside a @Task!"}
foo

[fellhorn]

@fg91 and I quickly debugged the promise.py where we log this error message and could not find a simple solution to detect that an @task is called within an @dynamic instead of an @task.

Therefore we created an issue here to continue the discussion: flyteorg/flyte#3995

[oliverhu]

Let's follow up in flyteorg/flyte#3995