Input Parameter Validation

[FloSchick]

Summary

I would like to propose a new feature for Argo Workflows that enhances user experience by adding input parameter validation directly within the UI.

The idea is to enable real-time validation of input parameters against predefined patterns (such as regular expressions) directly in the UI. If a user inputs a parameter that does not match the specified regex pattern, an error message should be immediately displayed, preventing the workflow from being submitted until the input is corrected.

This feature would be particularly useful for workflows that require strict input formats. By validating input parameters in real time, users can avoid common mistakes and ensure that their workflows are submitted with correct and valid data. This could significantly reduce errors and the need for re-runs, improving overall efficiency.

Use Cases

Imagine a scenario where non-technical users are responsible for initiating Argo Workflows. These users may not be familiar with the exact formatting requirements for input parameters. Without validation, they might input data that causes the workflow to fail, leading to additional manual effort to diagnose the issue and rerun the workflow. With input parameter validation directly in the UI, these users receive immediate feedback if their input is incorrect, preventing the workflow from failing. This ensures that the workflow runs smoothly the first time, reducing errors and saving time.

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[agilgur5]

I've mentioned doing this before too on Slack and probably elsewhere too.

I was thinking to validate input params everywhere, and not just in the UI.
Re-using expr expressions would be preferable for validation, but they're only supported in the back-end right now and not in the UI, so I was thinking maybe we just do regex validation, which can be implemented everywhere.

[MasonM]

This could be done using validating admission policy without any changes to Argo. The main problem right now is they require using the full CRDs, which are currently broken, so I entered I entered #14044 to fix them. See #14045 for an example ValidatingAdmissionPolicy.

[FloSchick]

Thanks, @MasonM for sharing this! It’s a very clever solution, and I’ll definitely give it a try once the PR is merged. That said, I still hope to see native support from Argo in the future. My request is more focused on user-friendliness rather than security.

For example, a non-technical user submitting a workflow via the UI, as described in my scenario, could still be confused if the workflow is blocked by the validation admission policy. In such cases, it would be helpful to know how the UI will handle this scenario. Will it display a 401 error, or will there be another user-friendly way to communicate the rejection?