Migrate to new Kubernetes events API

[adri1197]

Migrates the controller's event recording from the legacy k8s.io/client-go/tools/record interface to github.com/fluxcd/pkg/runtime/events, which emits structured events.k8s.io/v1 Events, and moves the event payload API from fluxcd/pkg/apis/event/v1beta1 to fluxcd/pkg/apis/event/v1.

• Replace kuberecorder.EventRecorder with events.Recorder in the Alert, Provider and Receiver reconcilers and in the EventServer.
• Switch event emission to the event/v1 Eventf signature, adding an explicit Action (Reconciled, Failed, Validating, Fetching) and Related object argument.
• Migrate all notifier backends from event/v1beta1 to event/v1; the dispatched payload now carries the action field
• Use mgr.GetEventRecorder / testEnv.GetEventRecorder and events.NewFakeRecorder in tests instead of the client-go equivalents.
• Document the new relatedObject field and event/v1 reference in the event spec.
• Bump Kubernetes to 0.37, controller-runtime to 0.25 and the fluxcd/pkg modules as a set

Part of fluxcd/flux2#5761

[matheuscscp]

I think this is a change that needs to be done in fluxcd/pkg first

[adri1197]

I think this is a change that needs to be done in fluxcd/pkg

Is there a reason notification-controller hasn't been migrated to fluxcd/pkg for Events yet? I see it’s already implemented in helm-controller. I'm happy to include that migration here as I've already begun the work.

[matheuscscp]

I think this is a change that needs to be done in fluxcd/pkg

Is there a reason notification-controller hasn't been migrated to fluxcd/pkg for Events yet? I see it’s already implemented in helm-controller. I'm happy to include that migration here as I've already begun the work.

Yes, a very specific one: fluxcd/pkg wraps k8s EventRecorder to fan out to notification-controller. But notification-controller can't send events to itself, hence why it doesn't use it. I guess what I meant is: if we're gonna migrate to the new Event API, it has to start with fluxcd/pkg, which is for the other Flux controllers 👌

[adri1197]

I think this is a change that needs to be done in fluxcd/pkg

Is there a reason notification-controller hasn't been migrated to fluxcd/pkg for Events yet? I see it’s already implemented in helm-controller. I'm happy to include that migration here as I've already begun the work.

Yes, a very specific one: fluxcd/pkg wraps k8s EventRecorder to fan out to notification-controller. But notification-controller can't send events to itself, hence why it doesn't use it. I guess what I meant is: if we're gonna migrate to the new Event API, it has to start with fluxcd/pkg, which is for the other Flux controllers 👌

Got it! Will start with fluxcd/pkg, then. Thanks a lot! 😃