WorkflowStep when condition behavior changes after v3.1

[tczhao]

Summary

What happened/what you expected to happen?

With #5115, the when condition is now evaluated as an expr

The below template works prior to v3.1

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: conditional-
  namespace: default
spec:
  entrypoint: conditional-example
  arguments:
    parameters:
    - name: should-print
      value: "2021-01-01-test"

  templates:
  - name: conditional-example
    inputs:
      parameters:
      - name: should-print
    steps:
    - - name: print-hello
        template: whalesay
        when: "{{inputs.parameters.should-print}} != 2021-01-01"

  - name: whalesay
    container:
      image: docker/whalesay:latest
      command: [sh, -c]
      args: ["cowsay hello"]

However, with the expression update, if a value starts with number, it gets interpreted as numeric token

Currently, I put a single quote around to make it work.

when: "'{{inputs.parameters.should-print}}' != '2021-01-01'"

Maybe we need to document this or update the code to make it align with the old behavior?

---

Message from the maintainers:

Impacted by this bug? Give it a 👍. We prioritise the issues with the most 👍.

[sarabala1979]

Expression evaluation is refactored to support Goevaluate and expr v3.x onwards. It expects ' for string comparison.

[sarabala1979]

@alexec I don't think we can fix this. fasttemplate will consider all left and right is a string. But after changed govaluate, it is typed strict evaluator. User has to wrap the ' if the value start with number or date.

[alexec]

I've documented this is the upgrading guide.