feat: support inline configurations

[TLDMain]

Relevant issue #1966

[linux-foundation-easycla]

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[stormqueen1990]

Hi there, @TLDMain!

Thanks for your contribution!

This PR is referring to an old issue that was closed before it was triaged. Could you please elaborate on what is the use case you're trying to address here?

/hold

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/lifecycle stale

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[TLDMain]

Hi there, @stormqueen1990!

Thanks for your feedback!

This PR addresses the need to streamline kustomize configurations by allowing inlined configurations directly within the kustomization.yaml file, similar to how patches are currently handled. The use case here is to simplify the sharing and management of kustomize configurations by embedding them within a single file, eliminating the need for separate configuration files. This makes it easier to provide comprehensive and portable examples.

For instance, with this change, configurations can be inlined as follows:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
  - helmrelease.yaml
configMapGenerator:
  - name: helmrelease-values
    files:
      - values.yaml=helmrelease.values.yaml
configurations:
  - |
    nameReference:
      - kind: ConfigMap
        version: v1
        fieldSpecs:
          - path: spec/valuesFrom/name
            kind: HelmRelease

This enhancement allows users to consolidate their configurations, making it more convenient to manage and share kustomize setups.

/remove-lifecycle stale
/label tide/merge-method-squash

[stormqueen1990]

/triage under-consideration

[varshaprasad96]

This looks good to me! Thank you!
/lgtm

I'll wait for approval, still some other maintainer can also take a look.
cc: @stormqueen1990 @antoooks

[TLDMain]

Hi @koba1t.

I suggest two options for checking: either use regex to verify that the string contains a file path, or check if the string contains multiple lines.

Alternatively, you can propose your own method for checking.

[koba1t]

@TLDMain
I am so sorry for the delayed response.

I have one suggestion.
If the contents of the field are a single line, the method is to go looking for the file to which it refers.

regexp would be difficult because different operating systems interpret them in different ways. Perhaps in the future there may be content that can be expressed on a single line, so it would be safer to check if it can be resolved with the file open function.

[k8s-ci-robot]

New changes are detected. LGTM label has been removed.

[TLDMain]

Hi. @koba1t.

Thank you for the suggestion!
I implemented the check for a newline in the configuration content, as you recommended.

However, this led to unexpected behavior: YAML files can be written in a single line, which caused issues with accurately interpreting the variable's content.
For example:

configurations:
  -  '{ images: [ { kind: MyKind, path: spec/container/image } ] }'

The previous approach, which attempted to parse YAML directly into a TransformerConfig structure, provided a better guarantee of correct content recognition.
I would revert to the previous behavior, as it covers more cases without errors.

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/lifecycle stale

[TLDMain]

/remove-lifecycle stale

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The Kubernetes project currently lacks enough contributors to adequately respond to all PRs.

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/lifecycle stale

[TLDMain]

/remove-lifecycle stale

[TLDMain]

Hi, @koba1t! Can you do a review?

[k8s-triage-robot]

The Kubernetes project currently lacks enough contributors to adequately respond to all PRs.

This bot triages PRs according to the following rules:

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/lifecycle stale

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: stormqueen1990, TLDMain
Once this PR has been reviewed and has the lgtm label, please ask for approval from varshaprasad96. For more information see the Code Review Process.

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[TLDMain]

/remove-lifecycle stale

[koba1t]

Hi @TLDMain

Thanks for your contributon!
I think almost good to code fix!

To verify functionality and prevent regressions, I propose adding the following tests:

• When multiple transformer configurations are included in a single configurations block
• When a single transformer configuration appears multiple times as a list within configurations
• When inline configurations are syntactically correct YAML but contain incorrect config keys or other issues preventing proper interpretation by the transformer
• When inline configurations contain invalid YAML syntax

[stormqueen1990]

/uncc