CEL for CRD AdditionalPrinterColumns

[sreeram-venkitesh]

Enhancement Description

• One-line enhancement description (can be used as a release note): Provide a more powerful way to express human readable printer columns exposed by CRDs than simple JSON paths.
• Kubernetes Enhancement Proposal: KEP 4595: CEL for CRD AdditionalPrinterColumns #4602
• Discussion Link: https://docs.google.com/document/d/1V8mo6tbApM8o1ZrYcJBms95oVojxCnIi-EomWupEPp8/edit?usp=sharing
• Primary contact (assignee): @sreeram-venkitesh @Priyankasaggu11929
• Responsible SIGs: api-machinery
• Enhancement target (which target equals to which milestone):
  • Alpha release target (x.y): 1.34
  • Beta release target (x.y):
  • Stable release target (x.y):
• Alpha
  • KEP (k/enhancements) update PR(s): KEP 4595: CEL for CRD AdditionalPrinterColumns #4602
  • Code (k/k) update PR(s):
  • Docs (k/website) update PR(s):

Please keep this description up to date. This will help the Enhancement Team to track the evolution of the enhancement efficiently.

[sreeram-venkitesh]

/sig api-machinery

[kannon92]

@sreeram-venkitesh really looking forward to this feature!

We ran into this for JobSet and it would be great to have something like this!

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[msvticket]

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[damsien]

@sreeram-venkitesh When it is accepted, if you need any help about the implementation, I would like to get involved if it is possible!

[sreeram-venkitesh]

Quick update on the status of this KEP: We have implemented a new CEL based expression field for CRD additionalPrinterColumns. With this we are now able to define and print additionalPrinterColumns with CEL expressions. We have tested printing different types of columns (strings, integers, durations, timestamps, lists and maps).

Here's a small example CRD demonstrating CEL expressions which evaluate to lists and uses conditionals to compute column values based on other fields defined in the CRD schema: