Different behavior on output artifact between Argo v3.4 and Argo 3.6

[carolkao]

Hi team,

I'd like to consult a different behavior between Argo workflow v3.4 and v3.6. I'd like to know what is your expected behavior.

I have a workflowtemplate - script-executor with an optional artifact

piVersion: argoproj.io/v1alpha1
kind: WorkflowTemplate
metadata:
  name: script-executor
spec:
  entrypoint: main
  templates:
    - name: main
      inputs:
        parameters:
          - name: script
        artifacts:
          - name: inputFile
            optional: true
            path: /tmp/inputFile
      outputs:
        artifacts:
          - name: resultFile
            optional: true
            path: '{{inputs.parameters.outputArtifactResultFilePath}}'
      script:
        image: 'debian:9.4'
        command: [ 'bash' ]
        source: '{{inputs.parameters.script}}'

I have an workflow - randomly-output-artifact reference it, and define an output artifact without optional property :

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  name: randomly-output-artifact
spec:
  templates:
    - name: main
      outputs:
        artifacts:
          - name: result
            from: "{{steps.run.outputs.artifacts.resultFile}}"
      steps:
        - - name: run
            templateRef:
              name: script-executor
              template: main
            arguments:
              parameters:
                - name: script
                  value: |
                    if [ "$((RANDOM % 2))" == "0" ]; then
                      echo "put 'hello' to output file"
                      echo "hello" > /tmp/output
                    else
                      echo "just echo hello"
                      echo "hello"
                    fi

The run step will sometimes have no output artifact.

In v3.4, no matter the run step produce output artifact or not, the randomly-output-artifact workflow can completed successfully (with or without output artifact). But in v3.6, it encounter error Unable to resolve: "steps.run.outputs.artifacts.resultFile"

Looks like in the old version, the optional: true characteristic will be auto propagate to the caller Workflow / WorkflowTemplate, but this feature is gone in the new version.

I'd like to know what is your expectation of such behavior.