In a Kubernetes operator based on operator-sdk, do you know how to write code to synchronize CR resource when CR specification is updated with kubectl apply? Could you please provide some code samples?
Implementing it a go-lang based operator is pretty complex, and I would recommand studying the kubebuilder documentation and example in order to achieve that: https://book.kubebuilder.io/cronjob-tutorial/controller-implementation.html#implementing-a-controller