Skip to content

Loops Arbitrary Sequential Steps

Note

This example is a replication of an Argo Workflow example in Hera. The upstream example can be found here.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
from hera.expr import g
from hera.workflows import Container, Parameter, Step, Steps, Workflow

with Workflow(
    generate_name="loop-arbitrary-sequential-steps-",
    entrypoint="loop-arbitrary-sequential-steps-example",
    arguments={  # Serialized json string used to match upstream example. You can directly use a list here instead
        "step_params": """[
  { "exit_code": 0, "message": "succeeds 1" },
  { "exit_code": 0, "message": "succeeds 2" },
  { "exit_code": 0, "message": "succeeds 3" },
  { "exit_code": 1, "message": "will fail and stop here" },
  { "exit_code": 0, "message": "will not run" },
  { "exit_code": 0, "message": "will not run" }
]
"""
    },
) as w:
    unit_step_template = Container(
        name="unit-step-template",
        image="alpine",
        command=["/bin/sh", "-c"],
        args=["echo {{inputs.parameters.message}}; exit {{inputs.parameters.exit_code}}"],
        inputs=[
            Parameter(name="exit_code"),
            Parameter(name="message"),
        ],
    )
    with Steps(
        name="loop-arbitrary-sequential-steps-example",
        inputs=[Parameter(name="step_params")],
        parallelism=1,
        fail_fast=True,
    ) as s:
        Step(
            name="unit-step",
            template=unit_step_template,
            arguments={
                "exit_code": f"{g.item.exit_code:$}",
                "message": f"{g.item.message:$}",
            },
            with_param=s.get_parameter("step_params"),
        )

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: loop-arbitrary-sequential-steps-
spec:
  arguments:
    parameters:
    - name: step_params
      value: |
        [
          { "exit_code": 0, "message": "succeeds 1" },
          { "exit_code": 0, "message": "succeeds 2" },
          { "exit_code": 0, "message": "succeeds 3" },
          { "exit_code": 1, "message": "will fail and stop here" },
          { "exit_code": 0, "message": "will not run" },
          { "exit_code": 0, "message": "will not run" }
        ]
  entrypoint: loop-arbitrary-sequential-steps-example
  templates:
  - container:
      args:
      - echo {{inputs.parameters.message}}; exit {{inputs.parameters.exit_code}}
      command:
      - /bin/sh
      - -c
      image: alpine
    inputs:
      parameters:
      - name: exit_code
      - name: message
    name: unit-step-template
  - failFast: true
    inputs:
      parameters:
      - name: step_params
    name: loop-arbitrary-sequential-steps-example
    parallelism: 1
    steps:
    - - arguments:
          parameters:
          - name: exit_code
            value: '{{item.exit_code}}'
          - name: message
            value: '{{item.message}}'
        name: unit-step
        template: unit-step-template
        withParam: '{{inputs.parameters.step_params}}'

Comments