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Recursive Dag

This example shows how you can (carefully!) recurse on a DAG template.

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from hera.workflows import DAG, Task, Workflow, script


@script()
def random_roll():
    import random

    print(random.randint(1, 6))


with Workflow(generate_name="recursive-dag-", entrypoint="dag") as w:
    with DAG(name="dag") as dag:
        random_number = random_roll(name="roll")
        recurse = Task(
            name="recurse-if-not-six",
            template=dag,
            when=f"{random_number.result} != 6",
        )
        random_number >> recurse

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apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: recursive-dag-
spec:
  entrypoint: dag
  templates:
  - name: dag
    dag:
      tasks:
      - name: roll
        template: random-roll
      - name: recurse-if-not-six
        depends: roll
        template: dag
        when: '{{tasks.roll.outputs.result}} != 6'
  - name: random-roll
    script:
      image: python:3.10
      source: |-
        import os
        import sys
        sys.path.append(os.getcwd())
        import random
        print(random.randint(1, 6))
      command:
      - python

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