src/pydolphinscheduler/examples/tutorial_decorator.py

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r"""
A tutorial example take you to experience pydolphinscheduler.

After tutorial.py file submit to Apache DolphinScheduler server a DAG would be create,
and workflow DAG graph as below:

                  --> task_child_one
                /                    \
task_parent -->                        -->  task_union
                \                    /
                  --> task_child_two

it will instantiate and run all the task it have.
"""

import time

# [start tutorial]
# [start package_import]
# Import Workflow object to define your workflow attributes
from pydolphinscheduler.core.workflow import Workflow

# Import task Shell object cause we would create some shell tasks later
from pydolphinscheduler.tasks.func_wrap import task

# [end package_import]

scope_global = "global-var"


# [start task_declare]
@task
def print_something():
    """First task in this workflow."""
    print("hello python function wrap task")


@task
def depend_import():
    """Depend on import module."""
    time.sleep(2)


@task
def depend_global_var():
    """Depend on global var."""
    print(f"Use global variable {scope_global}")


@task
def depend_local_var():
    """Depend on local variable."""
    scope_global = "local"
    print(f"Use local variable overwrite global {scope_global}")


def foo():
    """Call in other task."""
    print("this is a global function")


@task
def depend_func():
    """Depend on global function."""
    foo()


# [end task_declare]


# [start workflow_declare]
with Workflow(
    name="tutorial_decorator",
    schedule="0 0 0 * * ? *",
    start_time="2021-01-01",
) as workflow:
    # [end workflow_declare]

    # [start task_relation_declare]
    task_group = [depend_import(), depend_global_var()]
    print_something().set_downstream(task_group)

    task_group >> depend_local_var() >> depend_func()
    # [end task_relation_declare]

    # [start submit_or_run]
    workflow.submit()
    # [end submit_or_run]
# [end tutorial]