[feature request] Reduce dependant resrouce creation boilerplate about controller-runtime

[DirectXMan12]

/kind feature

I think that some sort of Ensure method could be useful -- pass an object to Ensure, and we ensure that it's either created or up-to-date. Not sure of the precise design, but I'd be happy to review PRs and such, if you've got time to submit one.

[calind]

I would be glad to attempt a PR, but there are some design issues to address first.

Sometimes you need the eventually existing object first from the apiserver so that you can update/sync only some fields. In order to do this, you need to call the Get method, so this CreateOrUpdate won't fit in any interfaces (Reader or Writer).

One workaround I'm employing right now is that I manually implement CreateOrUpdate right into the reconciler (see https://github.com/presslabs/wordpress-operator/blob/51ece534c606a998807d7049a942e5c9de701646/pkg/controller/wordpress/wordpress_controller.go#L89).

What are your thoughts about this?

[DirectXMan12]

it could probably be a helper method in utils that takes in a Reader/Writer.