Make sampleexternalplugin a Valid Reference Implementation

[camilamacedo86]

Problem

The current sampleexternalplugin is outdated and fails to reflect real-world plugin development practices:

• Does not align with the internal plugin architecture
• Lacks use of the PROJECT config for inputs like domain/layout/version
• Fails on standard commands like create webhook or create api
• Contains mock scaffolding logic that isn’t meaningful for operators
• Hard to test locally — imports Kubebuilder from a release module, not the working source

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Suggested Improvements

• Match internal plugin architecture

  • Use config.Config and read/write from PROJECT using the same APIs as native plugins
  • Generate scaffolding through the Universe pattern as expected

• Replace mock scaffolding with real integration
  If create api or create webhook are kept, the plugin should scaffold real config, or invoke go.kubebuilder.io/v4 properly.
  Preferred: make the plugin useful by integrating a config-generation workflow —

  • e.g., kubebuilder edit --generate-bundle for OLM/operator distribution
  • OR generate a Prometheus monitor setup, which is currently embedded in golang/v4 but could be optional and moved into an external plugin.
  • Any config that makes sense to be optional (and not in the default scaffold) would be a good candidate.

• Support config-driven workflows
  Use values from PROJECT instead of hardcoded values or CLI-only inputs

• Use the local Kubebuilder repo code
  Switch the go.mod to:

  replace sigs.k8s.io/kubebuilder/v4 => ../../../../../

  This ensures contributors can test the plugin in PRs and local workflows.

• Add a go.mod file
  Supports proper CI/testability and makes plugin development easier.

• Update documentation
  The example shown in the book should be updated to reflect these changes — particularly if we drop create api in favor of a more realistic integration path like edit.

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Goal

Turn the sample plugin into a realistic, working, and testable reference:

• Based on how real Kubebuilder plugins work
• Produces meaningful project output (e.g., operator bundles, optional configs like Prometheus monitors or CRD dashboards)
• Helps plugin developers test against local changes and internal APIs
• Keeps docs and examples in sync with real expected usage
• We might start to release this external plugin with Kubebuilder, for example.

We need a full, valid implementation.