feat: delete clusters when shoot is deleted (#45)

[jellonek]

Closes #45

[Copilot]

Pull request overview

This PR implements cleanup of Greenhouse Cluster resources when the corresponding Gardener Shoot is deleted (404 on previously existing Shoot), and documents the new behavior/events.

Changes:

• Add logic in the Shoot controller to delete an existing Greenhouse Cluster when the Shoot can no longer be fetched due to NotFound.
• Emit a new ClusterDeleted event and document it in the README.
• Add a test intended to validate cluster deletion behavior on Shoot removal.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
README.md	Updates documentation to reflect cluster cleanup behavior and adds the ClusterDeleted event.
controller/shoot/shoot_controller.go	Implements deletion of the Greenhouse Cluster when the Shoot is deleted and emits a ClusterDeleted event.
controller/shoot/shoot_controller_test.go	Adds a new test case intended to cover Shoot removal leading to Cluster cleanup.

Comments suppressed due to low confidence (1)

controller/shoot/shoot_controller.go:120

• existingClusterFound is computed incorrectly and will be false both when the Cluster exists (err == nil) and when it is NotFound, but true for non-NotFound errors. This prevents cluster deletion on Shoot deletion and can also cause an attempted delete of an empty Cluster object when the initial Get fails for transient reasons.

Handle the Cluster Get result explicitly: set existingClusterFound = true only when err == nil, return early on non-NotFound errors, and keep it false on NotFound.

	existingClusterFound := false
	err := r.GreenhouseClient.Get(ctx, client.ObjectKey{Name: req.Name, Namespace: r.CareInstruction.Namespace}, &existingCluster)
	if err == nil {
		// Cluster exists - check ownership
		if ownerLabel, hasLabel := existingCluster.Labels[v1alpha1.CareInstructionLabel]; hasLabel && ownerLabel != r.CareInstruction.Name {

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

[github-actions]

Merging this branch will decrease overall coverage

Impacted Packages	Coverage Δ	🤖
shoot-grafter/controller/shoot	78.83% (-0.26%)	👎

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Coverage by file

Changed files (no unit tests)

Changed File	Coverage Δ	Total	Covered	Missed	🤖
shoot-grafter/controller/shoot/shoot_controller.go	83.69% (-0.93%)	141 (+11)	118 (+8)	23 (+3)	👎

Please note that the "Total", "Covered", and "Missed" counts above refer to code statements instead of lines of code. The value in brackets refers to the test coverage of that file in the old version of the code.

Changed unit test files

• shoot-grafter/controller/shoot/shoot_controller_test.go