metacontroller VS keepalived-operator

It worth adopt proper controller development with something like Metacontroller, Kopf or Java Operator SDK.

There are many frameworks, like the Operator Framework (https://operatorframework.io/) to the MetaController (https://github.com/metacontroller/metacontroller) to KubeBuilder(https://github.com/kubernetes-sigs/kubebuilder) to the Kubernetes Operator Framework (kopf, https://kopf.readthedocs.io/en/stable/), among others.

You might like a little alternative to writing your own in the first instance:) take a look at https://metacontroller.github.io/metacontroller/

Codegen is not magic, but if you want to make it simple stupid, supportable and prod-usable I'd go for metacontroller. There's not much magic to it - just common admission/validation webhooks propagated to your controller implementation, alongside the simplest possible reconciliation cycle. We had adopted Knative driven metacontrollers and it's a pretty solid approach.

https://github.com/metacontroller/metacontroller - Sounds cool! I will look into it.

When I need a quick mutating controller, I like to use MetaController, which makes rapid prototyping really easy: https://metacontroller.github.io/metacontroller/

If you are more into lightweight and common use cases, look at metacontroller or the shell-operator.

In case you've not heard of it, the metacontroller aims to do exactly this. It provides the controller-lifecycle (registering your types, watching the API for changes, etc), you just need to provide a HTTP webhook to receive the JSON object, and respond with the modifications\resources you want.