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With Sequence

This example shows how to generate and parallelize generated sequences.

with_sequence takes a Sequence object and works similarly to Python’s range function.

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from hera.workflows import DAG, Workflow, script
from hera.workflows.models import Sequence


@script()
def gen_num():
    import random

    print(random.randint(4, 6))


@script()
def say(message: str):
    print(message)


with Workflow(generate_name="with-sequence-", entrypoint="d") as w:
    with DAG(name="d"):
        t1 = gen_num(name="t1")

        # This Sequence counts up from 0 to the number
        # generated by the first task
        t2 = say(
            name="t2",
            with_sequence=Sequence(count=t1.result, start="0"),
            arguments={"message": "{{item}}"},
        )

        # This Sequence counts down to 1 from the number generated
        # by the first task, and uses a formatting string to give
        # the value of `{{item}}`
        t3 = say(
            name="t3",
            with_sequence=Sequence(
                start=t1.result,
                end="1",
                format="2020-05-%02X",
            ),
            arguments={"message": "{{item}}"},
        )
        t1 >> [t2, t3]

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apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: with-sequence-
spec:
  entrypoint: d
  templates:
  - name: d
    dag:
      tasks:
      - name: t1
        template: gen-num
      - name: t2
        depends: t1
        template: say
        arguments:
          parameters:
          - name: message
            value: '{{item}}'
        withSequence:
          count: '{{tasks.t1.outputs.result}}'
          start: '0'
      - name: t3
        depends: t1
        template: say
        arguments:
          parameters:
          - name: message
            value: '{{item}}'
        withSequence:
          end: '1'
          format: 2020-05-%02X
          start: '{{tasks.t1.outputs.result}}'
  - name: gen-num
    script:
      image: python:3.10
      source: |-
        import os
        import sys
        sys.path.append(os.getcwd())
        import random
        print(random.randint(4, 6))
      command:
      - python
  - name: say
    inputs:
      parameters:
      - name: message
    script:
      image: python:3.10
      source: |-
        import os
        import sys
        sys.path.append(os.getcwd())
        import json
        try: message = json.loads(r'''{{inputs.parameters.message}}''')
        except: message = r'''{{inputs.parameters.message}}'''

        print(message)
      command:
      - python

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