examples/conditionals.yaml

# Conditionals provide a way to affect the control flow of a
# workflow at runtime, depending on parameters. In this example
# the 'print-hello' template may or may not be executed depending
# on the input parameter, 'should-print'. When submitted with:
#   argo submit examples/conditionals.yaml
# the step will be skipped since 'should-print' will evaluate false.
# When submitted with:
#   argo submit examples/conditionals.yaml -p should-print=true
# the step will be executed since 'should-print' will evaluate true.
apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: conditional-
spec:
  entrypoint: conditional-example
  arguments:
    parameters:
    - name: should-print
      value: "true"

  templates:
  - name: conditional-example
    inputs:
      parameters:
      - name: should-print
    steps:
    - - name: print-hello-govaluate
        template: argosay
        when: "{{inputs.parameters.should-print}} == true" # govaluate form
      - name: print-hello-expr
        template: argosay
        when: "{{= inputs.parameters[\"should-print\"] == 'true'}}" # expr form; note: a dash in the name requires the use of brackets and quotes for expr to handle
      - name: print-hello-expr-json
        template: argosay
        when: "{{=jsonpath(workflow.parameters.json, '$[0].value') == 'true'}}" # expr form

  - name: argosay
    container:
      image: argoproj/argosay:v1
      command: [sh, -c]
      args: ["cowsay hello"]