use of a scripting language

[errordeveloper]

Would maintainers consider supporting a scripting language, e.g. Skylark, as a way to provide user with an ability to implement custom generators and transforms?

Here is an example:

# kustomisations.yaml
resources:
   - deployment.yaml
scripts:
    - include.py
call:
    - doGenerateMyObject(1)
    - doZeroTransform()

# include.py
def doGenerateMyObject(param):
  return {
      'kind': 'MyObject',
      'apiVersion': 'examples.k8s.io/v1',
      'spec': { 'param': param },
  }

def doZeroTransform(input):
  return input

This example is just a simplest thing I could think of, I'm not saying this is essential to a CRD use-case or anything else.

At this point, all wondering about is whether kustomize authors may support these sort of things in the future or it's considered too harmful?

From my point of view, it seems like at one point users will need all sort of things built-in, and having to add any arbitrary thing upstream won't make sense. Ultimately, being able to leverage a full-blown language helps, and as long as the execution environment is sandboxed, it's ought to be possible to provide certain basic guarantees.

[monopole]

skylark, bazel and their Google antecedents are fine tools. bazel is awesome.

kustomize aspires to DAM, and therefore eschews introducing a language into k8s configuration. DAM best practices come from lessons learned running large, complex clusters at G, with lots of staff churn.

Folks that want to take a language-based approach to k8s config might try ksonnet, pulumi or one of others listed in this spreadsheet.

[monopole]

Oh, and thanks. That's an excellent, well-posed question. And a good example of skylark in context.

[errordeveloper]

@monopole thanks, that's kind of what I was assuming, but wasn't sure whether there extensibility is a significant enough benefit to considered in favour of scripting.

[errordeveloper]

#2267 🎉

[irvifa]

I wonder if there's any documentation on how to specify the starlark function and the input value from the kustomize build