🐛 pkg/client: optionally allow caching of unstructured objects

[joelanford]

Based on #615, it seems like there is intent to allow the DelegatingClient to cache unstructured objects. This is behavior that was possible to use before v0.7.0 by using the NewClientFunc manager option and creating a custom DelegatingClient.

IMO, this could be considered a regression, but since a large chunk of this code was restructured in v0.7.0, I'm not sure if dropping support for unstructured caching was intentional.

This PR adds a new boolean field to the NewDelegatingClientInput struct that allows users to opt-in to caching unstructured objects.

[joelanford]

/retest

[joelanford]

/hold

For discussion.

[joelanford]

Looks like #1058 removed the exported DelegatingClient struct, which I think is the root cause of the regression, unless I'm missing something about how we can support caching unstructured objects without forcing users to reimplement their own delegating client.

[estroz]

Agreed that this is a regression.

/lgtm

[vincepri]

I'm +1 having the option to cache unstructured objects as well.

IIRC, the earlier version of the DelegatingClient was meant to be used to always go to a live client for unstructured objects https://github.com/kubernetes-sigs/controller-runtime/blob/release-0.5/pkg/client/split.go#L45-L61, we kept that behavior.

That said, as you mentioned the NewClientFunc option, which was replaced with NewClientBuider and an interface where folks can fill in with their own struct https://github.com/kubernetes-sigs/controller-runtime/blob/release-0.7/pkg/manager/client_builder.go#L25-L33, so I'm +1 supporting this as an option

/approve

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[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: estroz, joelanford, vincepri

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[coderanger]

Might also be good to set this up as a manager option too?

[joelanford]

/hold cancel

I'll add a manager option in a follow-up.

[estroz]

/cherry-pick release-0.7