conditional-parameters.yaml

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: conditional-parameter-
  labels:
    workflows.argoproj.io/test: "true"
  annotations:
    workflows.argoproj.io/description: |
      Conditional parameters provide a way to choose the output parameters based on expression.

      In this example the step template has two steps which will run conditionally on `when`.

      Based on that condition, one of step will not be executed. The step template's output parameter will be
      set from the executed step's output.
    workflows.argoproj.io/version: '>= 3.1.0'
spec:
  entrypoint: main
  templates:
    - name: main
      steps:
        - - name: flip-coin
            template: flip-coin
        - - name: heads
            template: heads
            when: "{{steps.flip-coin.outputs.result}} == heads"
          - name: tails
            template: tails
            when: "{{steps.flip-coin.outputs.result}} == tails"
      outputs:
        parameters:
          - name: stepresult
            valueFrom:
              expression: "steps['flip-coin'].outputs.result == 'heads' ? steps.heads.outputs.result : steps.tails.outputs.result"

    - name: flip-coin
      script:
        image: python:alpine3.6
        command: [ python ]
        source: |
          import random
          print("heads" if random.randint(0,1) == 0 else "tails")

    - name: heads
      script:
        image: python:alpine3.6
        command: [ python ]
        source: |
          print("heads")

    - name: tails
      script:
        image: python:alpine3.6
        command: [ python ]
        source: |
          print("tails")