refactor: split controller.go into focused files by concern

[bdehamer]

Summary

Splits the 995-line internal/controller/controller.go into four focused files organized by responsibility. Includes one bug fix; otherwise pure structural refactoring.

New file layout

File	Lines	Responsibility
controller.go	~195	Types, interfaces, Controller struct, New(), newAPIClient(), Run()
handlers.go	~205	registerEventHandlers(), runWorker(), processNextItem(), startWorkers()
reconcile.go	~450	processEvent(), recordContainer(), getWorkloadRef(), resolveJobWorkload(), workloadActive(), workload existence checks, getCacheKey()
pod.go	~195	createInformerFactory(), getARDeploymentName(), getContainerDigest(), getDeploymentName(), hasSupportedOwner(), isTerminalPhase(), getJobOwnerName(), getDaemonSetName(), getStatefulSetName(), isNumeric(), podToPartialMetadata()
config.go	42	Unchanged

Key changes

• registerEventHandlers() extracted from New() as a Controller method — the event handler closures now use c.workqueue instead of closing over a local queue variable.
• newAPIClient() extracted as a package-level helper to isolate API client construction from the controller constructor.
• startWorkers() extracted from Run() for clarity.

Bug fix

Fixed a pre-existing bug in DeleteFunc where cache.MetaNamespaceKeyFunc(obj) was called on the original obj, which may be a DeletedFinalStateUnknown tombstone. MetaNamespaceKeyFunc cannot extract the key from a tombstone, so delete events were silently dropped in that case. Now derives the key from the extracted pod instead.

Testing

All existing unit and integration tests pass without modification. No test changes needed since all files remain in the same package.

[Copilot]

Pull request overview

Refactors the Kubernetes deployment-tracker controller by splitting the previous monolithic internal/controller/controller.go into smaller files organized by responsibility, aiming to keep behavior unchanged while improving readability and maintainability.

Changes:

• Extracted event handler registration and worker lifecycle logic into handlers.go.
• Extracted reconciliation / posting logic into reconcile.go.
• Extracted pod/informer helper utilities into pod.go and simplified controller.go to core wiring (New, Run, API client construction).

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
internal/controller/controller.go	Slimmed down to core types + constructor + API client creation + Run(), delegating handlers/workers elsewhere.
internal/controller/handlers.go	New file containing informer event handlers and queue worker processing logic.
internal/controller/reconcile.go	New file containing processEvent/recordContainer and caching logic for posts.
internal/controller/pod.go	New file containing informer factory creation + pod/container helper functions.

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[Copilot]

@bdehamer I've opened a new pull request, #70, to work on those changes. Once the pull request is ready, I'll request review from you.

[ajbeattie]

Heads up, I'm probably about to merge this PR: #72

It adds/updates several functions/methods in controller.go, so it will probably have some conflicts with this refactor. I'm not 100% sure whether/how the new stuff will fit into the concept/file split proposed here, but hopefully it either fits or illuminates some other natural separation of functionality that can be further split out 😅

[piceri]

After the changes to support different "workloads", I wonder if having a workload.go file would make sense with the following:

controller.go

• New()
• Run()
• newAPIClient()
• createInformerFactory()

handlers.go

• registerEventHandlers()
• runWorker()
• startWorkers()
• processNextItem()
• isTerminalPhase()

workload.go

• getWorkloadRef()
• resolveJobWorkload()
• workloadActive()
• deploymentExists()
• jobExists()
• daemonSetExists()
• statefulSetExists()
• cronJobExists()
• getDeploymentName()
• getJobOwnerName()
• getDaemonSetName()
• getStatefulSetName()

event.go

• processEvent()
• recordContainer()
• getCacheKey()

pod.go

• isNumeric()
• podToPartialMetadata()
• getARDeploymentName()
• getContainerDigest()
• hasSupportedOwner()

Also wondering about event.go instead of reconcile.go. Very open to push back/other opinions