Feature flags to trim tekton results EOF newlines

[Tomcli]

Feature request

Related #2936
Some of our users have pre-defined container that doesn't trim the outputs. It is quite troublesome to ask everyone to fix and rebuild their container especially when we are building a pipeline that's depended on each other's work. Is it possible to add a feature flag for Tekton to handle it? Thank you in advance.

Here is an example to reproduce this:

apiVersion: tekton.dev/v1beta1
kind: PipelineRun
metadata:
  name: test-params
spec:
  params:
  - name: project_name
    value: 'a-project'
  - name: notebook_name
    value: 'a-notebook'
  pipelineSpec:
    params:
    - name: project_name
    - name: notebook_name
    tasks:
    - name: find-project
      params:
      - name: project_name
        value: $(params.project_name)
      taskSpec:
        params:
        - name: project_name
        results:
        - description: /tmp/outputs/project/data
          name: project
        steps:
        - command:
          - sh
          - -ex
          - -c
          - "echo \"$0\" > \"$1\""
          - $(inputs.params.project_name)
          - $(results.project.path)
          image: alpine:3.12
          name: main
    - name: find-asset
      params:
      - name: find-project-project
        value: $(tasks.find-project.results.project)
      - name: notebook_name
        value: $(params.notebook_name)
      taskSpec:
        params:
        - name: find-project-project
        - name: notebook_name
        steps:
        - command:
          - sh
          - -ex
          - -c
          - "echo \"'$0'\"\n echo \"'$1'\""
          - $(inputs.params.find-project-project)
          - $(inputs.params.notebook_name)
          image: alpine:3.12
          name: main

Tracking issue on our repo: kubeflow/kfp-tekton#273

/cc @pritidesai @animeshsingh

Use case

Thanks for the issue report. This has also recently come up in the context of stdout / stderr capture (comment thread here).

I agree I think this would be useful. Here's the way it might work:

# in a TaskSpec
results:
- name: my-result
  description: Foo bar result description.
  trimWhitespace: true

I hesitate to add yet more flags to the entrypoint binary so I think right now my preference would be that the Tekton Controller is responsible for performing the trimming after the result is sent back to it but that's an implementation detail. I'll write a TEP for it.

[XinruZhang]

I'm interested in working on it and will work with @sbwsg together :)
/assign @XinruZhang

[tekton-robot]

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Mark the issue as fresh with /remove-lifecycle stale with a justification.
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/lifecycle stale

Send feedback to tektoncd/plumbing.

In summary the feedback on this feature's TEP boiled down to the fact that working around this problem is quite easy for users. Removing trailing spaces can be done in the Task directly or by adding a Task to their pipeline to perform string trimming. Therefore it doesn't seem like this is a feature the Pipelines project should pursue. That doesn't preclude this being something the Pipelines project takes on in future when a clear need presents itself that users are unable to work around, but right now we don't see evidence of that kind of problem.

/close

[tekton-robot]

@sbwsg: Closing this issue.

Details

In response to this:

In summary the feedback on this feature's TEP boiled down to the fact that working around this problem is quite easy for users. Removing trailing spaces can be done in the Task directly or by adding a Task to their pipeline to perform string trimming. Therefore it doesn't seem like this is a feature the Pipelines project should pursue. That doesn't preclude this being something the Pipelines project takes on in future when a clear need presents itself that users are unable to work around, but right now we don't see evidence of that kind of problem.

/close

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