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Recursive Steps

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

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from hera.workflows import Step, Steps, WorkflowTemplate, script


@script(constructor="inline")
def random_roll():
    import random

    return random.randint(0, 2)


with WorkflowTemplate(name="my-workflow", entrypoint="steps") as w:
    with Steps(name="sub-steps") as sub_steps:
        random_number = random_roll()
        Step(
            name="recurse",
            arguments={"input-num": random_number.result},
            template=sub_steps,
            when=f"{random_number.result} != 0",
        )

    with Steps(name="steps"):
        sub_steps()

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apiVersion: argoproj.io/v1alpha1
kind: WorkflowTemplate
metadata:
  name: my-workflow
spec:
  entrypoint: steps
  templates:
  - name: sub-steps
    steps:
    - - name: random-roll
        template: random-roll
    - - name: recurse
        template: sub-steps
        when: '{{steps.random-roll.outputs.result}} != 0'
        arguments:
          parameters:
          - name: input-num
            value: '{{steps.random-roll.outputs.result}}'
  - name: random-roll
    script:
      image: python:3.10
      source: |-
        import os
        import sys
        sys.path.append(os.getcwd())
        import random
        return random.randint(0, 2)
      command:
      - python
  - name: steps
    steps:
    - - name: sub-steps
        template: sub-steps

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