feat(plugins): plugin controller deletion lifecycle

[Zaggy21]

Description

Fixes the plugin deletion lifecycle where the greenhouse.sap/cleanup finalizer was removed before Flux had finished running helm uninstall, potentially leaving orphaned Helm resources on the target cluster.

EnsureFluxDeleted now:

• Issues the delete on the HelmRelease and requeues,
• If the HelmRelease is still present, checks Flux's ReleasedCondition: an UninstallFailed reason surfaces as HelmUninstallFailedReason on the Plugin; otherwise sets HelmReleaseUninstallPendingReason and relies on the HelmRelease watch to re-trigger reconciliation,
• Only returns lifecycle.Success (removing the finalizer) once the HelmRelease is gone.

What type of PR is this? (check all applicable)

• 🍕 Feature
• 🐛 Bug Fix
• 📝 Documentation Update
• 🎨 Style
• 🧑‍💻 Code Refactor
• 🔥 Performance Improvements
• ✅ Test
• 🤖 Build
• 🔁 CI
• 📦 Chore (Release)
• ⏩ Revert

Related Tickets & Documents

• Closes [FEAT] - Plugin controller deletion lifecycle #1885

Added tests?

• 👍 yes
• 🙅 no, because they aren't needed
• 🙋 no, because I need help
• Separate ticket for tests # (issue/pr)

Adds unit tests covering the pending and failure paths, and an e2e scenario that injects an uninstall failure via a test finalizer on the HelmRelease and verifies the Plugin surfaces the condition and retains its finalizer until resolved.

Added to documentation?

• 📜 README.md
• 🤝 Documentation pages updated
• 🙅 no documentation needed
• (if applicable) generated OpenAPI docs for CRD changes

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• New and existing unit tests pass locally with my changes

[Copilot]

Pull request overview

This PR improves the Plugin controller’s deletion lifecycle to ensure the greenhouse.sap/cleanup finalizer is not removed until Flux has fully completed the HelmRelease uninstall (and to surface Flux uninstall failures on the Plugin status), preventing orphaned Helm resources.

Changes:

• Update EnsureFluxDeleted to wait for the Flux HelmRelease to be fully removed, requeue while uninstall is pending, and surface UninstallFailed via Plugin conditions.
• Skip Plugin reconciliation when the target Cluster is already being deleted (via DeletionTimestamp) by requeueing and setting a deletion-related condition.
• Add unit + e2e coverage for pending uninstall and uninstall-failure paths during Plugin deletion.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
internal/controller/plugin/util.go	Adds handling to defer reconciliation when the referenced Cluster is already being deleted.
internal/controller/plugin/plugin_controller_flux.go	Holds Plugin finalizer until HelmRelease deletion completes; detects Flux uninstall failure and reports it on Plugin conditions.
internal/controller/plugin/plugin_controller_flux_test.go	Adds unit tests for pending uninstall and uninstall failure condition surfacing.
e2e/plugin/scenarios/flux_controller.go	Adds an e2e scenario that injects HelmRelease uninstall failure and verifies Plugin behavior/finalizer retention.
e2e/plugin/e2e_test.go	Registers the new deletion lifecycle e2e scenario.
api/v1alpha1/plugin_types.go	Introduces HelmReleaseUninstallPendingReason condition reason constant.

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Comments suppressed due to low confidence (1)

internal/controller/plugin/plugin_controller_flux_test.go:456

• This Eventually block appends the Flux finalizer on every retry without checking if it’s already present. If the closure retries after a successful update, the finalizer can be duplicated. Consider guarding the append with a contains-check (or use an idempotent patch) to keep the test stable.

		By("adding the Flux finalizer to simulate a real Flux-managed HelmRelease")
		Eventually(func(g Gomega) {
			err := test.K8sClient.Get(test.Ctx, releaseKey, helmRelease)
			g.Expect(err).ToNot(HaveOccurred())
			helmRelease.Finalizers = append(helmRelease.Finalizers, helmv2.HelmReleaseFinalizer)
			err = test.K8sClient.Update(test.Ctx, helmRelease)
			g.Expect(err).ToNot(HaveOccurred())
		}).Should(Succeed())